DETAILED ACTION
Notice of Pre-AIA or AIA Status
The present application, filed on or after March 16, 2013, is being examined under the first inventor to file provisions of the AIA .
In the event the determination of the status of the application as subject to AIA 35 U.S.C. 102 and 103 (or as subject to pre-AIA 35 U.S.C. 102 and 103) is incorrect, any correction of the statutory basis (i.e., changing from AIA to pre-AIA ) for the rejection will not be considered a new ground of rejection if the prior art relied upon, and the rationale supporting the rejection, would be the same under either status.
Continued Examination Under 37 CFR 1.114
A request for continued examination under 37 CFR 1.114, including the fee set forth in 37 CFR 1.17(e), was filed in this application after final rejection. Since this application is eligible for continued examination under 37 CFR 1.114, and the fee set forth in 37 CFR 1.17(e) has been timely paid, the finality of the previous Office action has been withdrawn pursuant to 37 CFR 1.114. Applicant's submission filed on 9/8/25 has been entered.
Claims 16-29 and 31-39 are pending, wherein claims 31-39 were newly added.
Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
This application currently names joint inventors. In considering patentability of the claims the examiner presumes that the subject matter of the various claims was commonly owned as of the effective filing date of the claimed invention(s) absent any evidence to the contrary. Applicant is advised of the obligation under 37 CFR 1.56 to point out the inventor and effective filing dates of each claim that was not commonly owned as of the effective filing date of the later invention in order for the examiner to consider the applicability of 35 U.S.C. 102(b)(2)(C) for any potential 35 U.S.C. 102(a)(2) prior art against the later invention.
Claim(s) 16-20, 22-29, 33-34, 36, and 39 is/are rejected under 35 U.S.C. 103 as being unpatentable over Bonnet et al (US 2013/0174942, cited in IDS filed 2/06/23) in view of Okuyama (JP 2001-1355018 A, previously cited) and Takahashi (JP 2000-212633A).
Regarding claim 16, Bonnet et al teaches a method of casting a steel semi-product from a liquid steel (paragraph [0088]), the steel semi-product having a targeted composition in titanium of at least 3.5% in weight (paragraph [0018], 2.5 % – 7.2% Ti, paragraph [0021], preferably 4.6% to 6.9% Ti), the method comprising the following steps:
a) adding aluminum to the liquid steel so that liquid steel contains at least 0.1% by weight of aluminum (note that a step of adding aluminum is implied as the steel composition includes aluminum, paragraph [0018], 0.005% to 1.5% Al, overlapping the claimed range, paragraph [0051], effective for deoxidizing the steel);
c) adding titanium to the liquid steel to reach the targeted composition (note that a step of adding titanium is implied as the steel composition includes titanium, paragraph [0018], [0021], paragraph [0117], additions); and
d) casting the steel in the form of a semi-product (paragraph [0090]).
Bonnet et al is quiet to b) adding mineral compounds to the liquid steel, the mineral compounds containing CaF2 and aluminum and calcium and optionally magnesium, to reach and maintain a slag with a slag composition wherein the ratio of CaO versus Al2O3 is from 0.7 to 2 and the slag contains up to 25% by weight of CaF2, and then adding the titanium in step c).
Okuyama teaches a method for producing Ti-containing steel (paragraph [0001]) having an improved Ti yield (paragraph [0007]) by deoxidizing the molten steel in the ladle with Al (paragraph [0008]), adding a TiO2-containing substance to the slag in the ladle (paragraph [0008]), adjusting the composition of the slag so that the CaO and Al2O3 content falls within the range of 1.3 to 2.5 (paragraph [0008], overlapping the claimed range), and then Ti and/or a Ti alloy is added to the molten steel (paragraph [0008]). The materials added to adjust the slag composition include burnt lime, alumina refractory waste, alumina, aluminum ash, etc (paragraph [0016]).
As Bonnet teaches the final steel composition for casting, but is quiet to how said steel was produced, it would have been obvious to one of ordinary skill in the art to modify Bonnet et al so as to include the teachings of Okuyama, such as including a TiO2 containing substance to the slag in the ladle, adjusting the composition of the slag so that CaO and Al2O3 falls within the range of 1.3 to 2.5 (overlapping the claimed range) by adding mineral components including burnt lime and alumina (Okuyama, paragraph [0016]), and then adding the Titanium to the liquid steel to reach the target composition (Okuyama, paragraph [0008]), as Okuyama teaches said steps improve the Ti yield and reduce the amount of expensive Ti sources (paragraph [0007]).
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05(I).
The combination of Bonnet et al as modified by Okuyama is quiet to the slag including CaF2 up to 25% by weight.
Takahashi teaches desulfurizing molten steel tapped from a converter by ladle refining (paragraph [0001]), as sulfur in steel generally has adverse effects such as impairing the toughness of the steel (paragraph [0002]). Takahashi teaches adding a slag modifier to modify the slag composition so that Al2O3 ≥ 30%, CaF2 ≥ 5%, 1.1 ≤ CaO/Al2O3 ≤ 1.8, and CaO/SiO2 ≥ 5.0 (paragraph [0010]). Takahashi teaches that it is important that the slag composition contains 5% or more of CaF2, as CaF2 combined with the effect of adding Al2O3, further lowers the melting point of the slag, promoting the melting of the slag modifier during ladle refining, and shortening the processing time (paragraph [0011]), noting that the limit is 20% as too much CaF2 will damage the ladle refractory (paragraph [0011]).
It would have been obvious to one of ordinary skill in the art to modify the slag composition of combination so as to include 5% or more of CaF2, as taught in Takahashi, as Takahashi recognizes that CaF2 lowers the melting point of the slag and promotes the melting of the slag modifier during ladle refining, shortening the processing time (Takahashi, paragraph [0011]).
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05(I).
Regarding claim 17, the combination teaches wherein the amount of aluminum added is such that the liquid steel contains more than 0.2% in weight of aluminum (Bonnet, paragraph [0018], 0.005% ≤ Al ≤ 1.5%, overlapping the claimed range).
Regarding claim 18, the combination teaches wherein the amount of aluminum added is such that the liquid steel contains more than 0.4% in weight of aluminum (Bonnet, paragraph [0018], 0.005% ≤ Al ≤ 1.5%, overlapping the claimed range).
Regarding claim 19, the combination teaches wherein the mineral compounds are chosen from the group consisting of: lime, spar CaF2 and magnesia (Okuyama, see rejection of claim 16 above, paragraph [0016], burnt lime as a material used to adjust the %CaO/%Al2O3, also note Takahashi teaches the CaF2 is from fluorite, paragraph [0015], (note that fluorite is also known as fluorspar and is the mineral compound of CaF2)).
Regarding claim 20, the combination teaches wherein the steel semi-product contains boron in a minimum percentage in weight fulfilling following equation: %B ≥ 0.45 x %Ti - 1.35% (Bonnet, paragraph [0018], (0.45 x Ti) – 0.35% ≤ B ≤ (0.45 x Ti) + 0.70%, overlapping the claimed range).
Regarding claims 22-23, the combination teaches adding boron (Bonnet, paragraph [0117], addition of boron), but is quiet to boron being added after step C (re: claim 22), or boron added during step B (re: claim 23).
However, it would have been obvious to add boron either after step C or during step B, as the courts have held that changes in sequence of adding ingredients to be obvious in the absence of new or unexpected results. Ex parte Rubin, 128 USPQ 440 (Bd. App. 1959). See also In re Burhans, 154 F.2d 690, 69 USPQ 330 (CCPA 1946). In re Gibson, 39 F.2d 975, 5 USPQ 230 (CCPA 1930). See MPEP 2144.04(IV)(C).
Regarding claim 24, the combination teaches wherein during step B, the CaF2 is added as spar CaF2 so as to reach a composition in CaF2 from 6 to 15% in weight (see combination, Takahashi, paragraph [0015], CaF2 added as fluorite (note fluorite is also known as fluorspar, the mineral form of CaF2), paragraph [0011], CaF2 of more than 5% and less than 20%, encompassing the claimed range).
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). "[A] prior art reference that discloses a range encompassing a somewhat narrower claimed range is sufficient to establish a prima facie case of obviousness." In re Peterson, 315 F.3d 1325, 1330, 65 USPQ2d 1379, 1382-83 (Fed. Cir. 2003). See also In re Harris, 409 F.3d 1339, 74 USPQ2d 1951 (Fed. Cir. 2005). MPEP 2144.05(I).
Regarding claim 25, the combination as discussed above is quiet to wherein during step B, magnesia is added so as to reach a composition in MgO comprised from 5% to 15% in weight.
Takahashi further teaches that it is preferable to set the MgO content of the modified slag to 9% or more, so as to suppress the corrosion of the ladle refractory (paragraph [0014]).
It would have been obvious to one of ordinary skill in the art to further include MgO into the slag so that the composition includes at least 9% (thus overlapping the claimed range), as Takahashi teaches that MgO in the slag composition suppresses corrosion of the ladle refractory (paragraph [0014]).
Regarding claim 26, the combination teaches wherein during step B the mineral compounds are added to reach the slag composition wherein the ratio of CaO versus Al2O3 is between 0.9 and 1.3 (Okuyama teaches a range of 1.3 to 2.5 (paragraph [0015]), thus overlapping the claimed range at the endpoint).
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05(I).
Regarding claim 27, the combination teaches wherein during step B the mineral compounds are added to reach the slag composition wherein the ratio of CaO versus Al2O3 is between 1.4 and 2 (Okuyama, paragraph [0015], 1.3 to 2.5, encompassing the claimed range, see MPEP 2144.05(I)), the slag furthermore includes between 6 and 12% in weight of CaF2 (see combination and claim 24 above, Takahashi teaches fluorite added so that CaF2 is 5% to 20% (paragraph [0011]), encompassing the claimed range).
Regarding claim 28, the combination teaches wherein the steel semi-product has a targeted composition in titanium of at least 5.8% in weight (Bonnet, paragraph [0018], 2.5 % ≤ Ti ≤ 7.2 %, overlapping the claimed range).
Regarding claim 29, the combination teaches wherein the steel semi-product has the following composition expressed in content by weight:
0.01% ≤ C ≤ 0.2% (Bonnet, paragraph [0018], 0.010% ≤ C ≤ 0.20%)
3.5% ≤ Ti ≤ 10% (Bonnet, paragraph [0018], 2.5 % ≤ Ti ≤ 7.2 %, overlapping the claimed range)
(0.45 x Ti) – 1.35% ≤ B ≤ (0.45 x Ti) + 0.70% (Bonnet, paragraph [0018], (0.45 x Ti) – 0.35% ≤ B ≤ (0.45 x Ti) + 0.70%, overlapping the claimed range)
S ≤ 0.03% (Bonnet, paragraph [0018], S ≤ 0.030%)
P ≤ 0.04% (Bonnet, paragraph [0018], P ≤ 0.040%)
N ≤ 0.05% (Bonnet does not disclose nitrogen, thus the presumption is 0% N)
O ≤ 0.05% (Bonnet does not disclose oxygen, thus the presumption is 0% O)
and comprising precipitates of TiB2 (Bonnet, paragraph [0016], TiB2 particles dispersed), a balance being Fe and unavoidable impurities resulting from processing (Bonnet, paragraph [0018]).
Note that the amount of Si, Mn, Al, Ni, Mo, Cr, Cu, Nb, V, and precipitates of Fe2B are claimed as optional and thus not a required feature of the claim, however, Bonnet discloses overlapping amounts of Si, Mn, Al, Ni, Mo, Cr, Nb, and V (paragraph [0018]) and optional Fe2B precipitates (paragraph [0026]).
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05(I).
Regarding claim 33, the combination as discussed above is quiet to during step B the mineral compounds are added to reach the slag composition wherein the ratio of CaO versus Al2O3 is from 0.7 to 1.1.
However, Takahashi teaches a slag composition of 1.1 ≤ CaO/Al2O3 ≤ 1.8 (paragraph [0010]), recognizing that if less than 1.1, the viscosity is too high, whereas if greater than 1.8, the slag melting point is too high which impairs the reactivity of the slag and prevents desulfurization (paragraph [0012]).
It would have been obvious to one of ordinary skill in the art to modify the CaO/Al2O3 ratio to be within 1.1 to 1.8, as taught in Takahashi, so as to impart the high desulfurization ability to the modified slag while preventing a too high viscosity or too high melting point, which would both impair the reactivity and prevent desulfurization (paragraph [0012]).
Regarding claim 34, the combination teaches during step B, the CaF2 is added as spar CaF2 so as to reach a composition in CaF2 from 10 to 25% in weight (note combination, see claim 24 above, Takahashi teaches in paragraphs [0011] and [0015] that CaF2 added as fluorite (also known as fluorspar) in an amount to modify the CaF2 to 5% to 20%, overlapping the claimed range).
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05(I).
Regarding claim 36, the combination teaches wherein titanium is added to the liquid steel only after step B (Okuyama, paragraph [0008], composition of the slag is adjusted (step B), and then Ti and/or a Ti alloy are added to the molten steel in the ladle, note that the step of adding a TiO2-containing substance is added to the slag).
Regarding claim 39, the combination as discussed above is quiet to the slag has a crystallization rate of 3.8% to 16.7%.
However, note that the combination above teaches the same composition of slag as claimed, including CaF2, CaO, and Al2O3, with ranges overlapping the claimed ranges. The claimed property of the crystallization rate is presumed to be inherent from the composition of the slag. Note that when the structure recited in the reference is substantially identical to that of the claims, claimed properties are presumed to be inherent. MPEP 2112.01.
Where the claimed and prior art products are identical or substantially identical in structure or composition, or are produced by identical or substantially identical processes, a prima facie case of either anticipation or obviousness has been established. In re Best, 562 F.2d 1252, 1255, 195 USPQ 430, 433 (CCPA 1977). MPEP 2112.01 (I).
Claim(s) 21 is/are rejected under 35 U.S.C. 103 as being unpatentable over Bonnet et al as modified by Okuyama and Takahashi as applied to claim 16 above, and further in view of Kos (US 4,512,804, previously cited).
Regarding claim 21, the combination is quiet to heating the liquid steel between steps A and B.
Kos teaches a method of making a steel (abstract) including melting a charge in a furnace, adding to the molten metal lime-containing and slag-forming additives, raising the charge to a tapping temperature, deoxidizing with an element having an affinity for oxygen, and then tapping into the casting ladle, adjusting the content of titanium, and then casting (col 3 lines 35-50, col 5 lines 15-35).
It would have been obvious to one of ordinary skill in the art to include a step of heating between steps A and B, as Kos teaches a heating step after covering with a slag and before deoxidizing with metallic aluminum, so as to raise the temperature of the melt to the desired tapping temperature.
Claim(s) 35 is/are rejected under 35 U.S.C. 103 as being unpatentable over Bonnet et al as modified by Okuyama and Takahashi as applied to claim 16 above, and further in view of Zhang (CN 106086594 A).
Regarding claim 35, the combination above is quiet to the slag composition contains less than 1% SiO2 by weight.
Zhang teaches preparing a Ti containing steel, including the steps of converter smelting, adjusting slag and ladle refining, RH refining, adjusting slag, then alloying of titanium, and then casting (abstract). Zhang teaches that the slag composition after adjustment and before the titanium alloying includes SiO2 ≤ 10 wt%, and in a more preferred embodiment, SIO2 ≤ 5% (machine translation, p.3, lines 19-44). Note that SiO2 ≤ 5% encompasses the claimed range of ≤1 %.
It would have been obvious to one of ordinary skill in the art to modify the wt% of SiO2 in the slag composition of the combination, as Zhang teaches an encompassing range of SiO2 is known, and that SiO2 is not desirable in Okuyama, as Okuyama recognizes that SiO2 in the slag reacts with Ti in the molten steel to product TiO2, which then reduces the Ti yield (paragraph [0005]).
Claim(s) 37 is/are rejected under 35 U.S.C. 103 as being unpatentable over Bonnet et al in view of Okuyama, JP 2000-345234A (cited in IDS filed 9/19/25), and Takahashi.
Regarding claim 37, Bonnet et al teaches a method of casting a steel semi-product from a liquid steel (paragraph [0088]), the steel semi-product having a targeted composition in titanium of at least 3.5% in weight (paragraph [0018], 2.5 % – 7.2% Ti, paragraph [0021], preferably 4.6% to 6.9% Ti), the method comprising the following steps:
a) adding aluminum to the liquid steel so that liquid steel contains at least 0.1% by weight of aluminum (note that a step of adding aluminum is implied as the steel composition includes aluminum, paragraph [0018], 0.005% to 1.5% Al, overlapping the claimed range, paragraph [0051], effective for deoxidizing the steel);
c) adding titanium to the liquid steel to reach the targeted composition (note that a step of adding titanium is implied as the steel composition includes titanium, paragraph [0018], [0021], paragraph [0117], additions); and
d) casting the steel in the form of a semi-product (paragraph [0090]).
Bonnet et al is quiet to b) adding mineral compounds to the liquid steel, the mineral compounds containing CaF2 and aluminum and calcium and optionally magnesium, to reach and maintain a slag with a slag composition wherein the ratio of CaO versus Al2O3 is from 0.7 to 2 and the slag contains up to 25% by weight of CaF2, and then adding the titanium in step c).
Okuyama teaches a method for producing Ti-containing steel (paragraph [0001]) having an improved Ti yield (paragraph [0007]) by deoxidizing the molten steel in the ladle with Al (paragraph [0008]), adding a TiO2-containing substance to the slag in the ladle (paragraph [0008]), adjusting the composition of the slag so that the CaO and Al2O3 content falls within the range of 1.3 to 2.5 (paragraph [0008], overlapping the claimed range), and then Ti and/or a Ti alloy is added to the molten steel (paragraph [0008]). The materials added to adjust the slag composition include burnt lime, alumina refractory waste, alumina, aluminum ash, etc (paragraph [0016]).
As Bonnet teaches the final steel composition for casting, but is quiet to how said steel was produced, it would have been obvious to one of ordinary skill in the art to modify Bonnet et al so as to include the teachings of Okuyama, such as including a TiO2 containing substance to the slag in the ladle, adjusting the composition of the slag so that CaO and Al2O3 falls within the range of 1.3 to 2.5 (overlapping the claimed range) by adding mineral components including burnt lime and alumina (Okuyama, paragraph [0016]), and then adding the Titanium to the liquid steel to reach the target composition (Okuyama, paragraph [0008]), as Okuyama teaches said steps improve the Ti yield and reduce the amount of expensive Ti sources (paragraph [0007]).
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05(I).
The combination of Bonnet et al as modified by Okuyama is quiet to the step of adding aluminum reduces TiOx content of a slag.
JP2000-345234A teaches a method for adding titanium to molten steel (paragraph [0001]) where titanium oxide-containing substates are added to the molten steel or slag (paragraph [0007]), and then reduced with aluminum (paragraph [0007]). Since an inexpensive titanium source containing titanium oxide is used and the titanium oxide is reduced by aluminum, titanium can be added to the molten steel more inexpensively and efficiently (paragraph [0013]). Additional sponge dititanium may be added as necessary to adjust the chemical composition (paragraph [0027]).
It would have been obvious to one of ordinary skill in the art to modify the combination such that the TiO2 added by Okuyama is reduced by the addition of aluminum as taught in JP2000-345234A, as a cheaper and more efficient way to increase the amount of titanium in the steel (paragraph [0005]).
The combination of Bonnet et al as modified by Okuyama and JP2000-345234A is quiet to the slag including CaF2 up to 25% by weight.
Takahashi teaches desulfurizing molten steel tapped from a converter by ladle refining (paragraph [0001]), as sulfur in steel generally has adverse effects such as impairing the toughness of the steel (paragraph [0002]). Takahashi teaches adding a slag modifier to modify the slag composition so that Al2O3 ≥ 30%, CaF2 ≥ 5%, 1.1 ≤ CaO/Al2O3 ≤ 1.8, and CaO/SiO2 ≥ 5.0 (paragraph [0010]). Takahashi teaches that it is important that the slag composition contains 5% or more of CaF2, as CaF2 combined with the effect of adding Al2O3, further lowers the melting point of the slag, promoting the melting of the slag modifier during ladle refining, and shortening the processing time (paragraph [0011]), noting that the limit is 20% as too much CaF2 will damage the ladle refractory (paragraph [0011]).
It would have been obvious to one of ordinary skill in the art to modify the slag composition of combination so as to include 5% or more of CaF2, as taught in Takahashi, as Takahashi recognizes that CaF2 lowers the melting point of the slag and promotes the melting of the slag modifier during ladle refining, shortening the processing time (Takahashi, paragraph [0011]).
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05(I).
Claim(s) 38 is/are rejected under 35 U.S.C. 103 as being unpatentable over Bonnet et al in view of Okuyama, Takahashi, and Zhang.
Regarding claim 38, Bonnet et al teaches a method of casting a steel semi-product from a liquid steel (paragraph [0088]), the steel semi-product having a targeted composition in titanium of at least 3.5% in weight (paragraph [0018], 2.5 % – 7.2% Ti, paragraph [0021], preferably 4.6% to 6.9% Ti), the method comprising the following steps:
a) adding aluminum to the liquid steel so that liquid steel contains at least 0.1% by weight of aluminum (note that a step of adding aluminum is implied as the steel composition includes aluminum, paragraph [0018], 0.005% to 1.5% Al, overlapping the claimed range, paragraph [0051], effective for deoxidizing the steel);
c) adding titanium to the liquid steel to reach the targeted composition (note that a step of adding titanium is implied as the steel composition includes titanium, paragraph [0018], [0021], paragraph [0117], additions); and
d) casting the steel in the form of a semi-product (paragraph [0090]).
Bonnet et al is quiet to b) adding mineral compounds to the liquid steel, the mineral compounds containing CaF2 and aluminum and calcium and optionally magnesium, to reach and maintain a slag with a slag composition wherein the ratio of CaO versus Al2O3 is from 0.7 to 2 and the slag contains up to 25% by weight of CaF2, and then adding the titanium in step c), wherein the slag has 35 % ≤ CaO ≤ 55%, 15% Al2O3 ≤ 55%, 0% ≤ MgO ≤15%, TiOx < 20%, and less than 1% of B2O3, SiO2, CrOx, MnO, NiO, FeOx, S.
Okuyama teaches a method for producing Ti-containing steel (paragraph [0001]) having an improved Ti yield (paragraph [0007]) by deoxidizing the molten steel in the ladle with Al (paragraph [0008]), adding a TiO2-containing substance to the slag in the ladle (paragraph [0008]), adjusting the composition of the slag so that the CaO and Al2O3 content falls within the range of 1.3 to 2.5 (paragraph [0008], overlapping the claimed range), and then Ti and/or a Ti alloy is added to the molten steel (paragraph [0008]). The materials added to adjust the slag composition include burnt lime, alumina refractory waste, alumina, aluminum ash, etc (paragraph [0016]). The TiO2 content in the slag is preferably 5 to 15 mass % so as to keep viscosity low while improving Ti yield (paragraph [0014]).
As Bonnet teaches the final steel composition for casting, but is quiet to how said steel was produced, it would have been obvious to one of ordinary skill in the art to modify Bonnet et al so as to include the teachings of Okuyama, such as including a TiO2 containing substance to the slag in the ladle, adjusting the composition of the slag so that CaO and Al2O3 falls within the range of 1.3 to 2.5 (overlapping the claimed range) by adding mineral components including burnt lime and alumina (Okuyama, paragraph [0016]), and then adding the Titanium to the liquid steel to reach the target composition (Okuyama, paragraph [0008]), as Okuyama teaches said steps improve the Ti yield and reduce the amount of expensive Ti sources (paragraph [0007]).
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05(I).
The combination of Bonnet et al as modified by Okuyama is quiet to the slag including CaF2 up to 25% by weight, wherein the slag has 35 % ≤ CaO ≤ 55%, 15% Al2O3 ≤ 55%, 0% ≤ MgO ≤15%, and less than 1% of SiO2.
Takahashi teaches desulfurizing molten steel tapped from a converter by ladle refining (paragraph [0001]), as sulfur in steel generally has adverse effects such as impairing the toughness of the steel (paragraph [0002]). Takahashi teaches adding a slag modifier to modify the slag composition so that Al2O3 ≥ 30%, CaF2 ≥ 5%, 1.1 ≤ CaO/Al2O3 ≤ 1.8, and CaO/SiO2 ≥ 5.0 (paragraph [0010]). Takahashi teaches that it is important that the slag composition contains 5% or more of CaF2, as CaF2 combined with the effect of adding Al2O3, further lowers the melting point of the slag, promoting the melting of the slag modifier during ladle refining, and shortening the processing time (paragraph [0011]), noting that the limit is 20% as too much CaF2 will damage the ladle refractory (paragraph [0011]). The reason for the Al2O3 content being 30% or more is that the melting point of CaO is lowered by the formation of an intermediate compound with Al2O3, thereby accelerating the formation of slag from CaO, increasing its reactivity, and shortening the desulfurization time (paragraph [0010]).
It would have been obvious to one of ordinary skill in the art to modify the slag composition of combination so as to include an overlapping amount of Al2O3 and CaO and 5% or more of CaF2, as taught in Takahashi, as Takahashi recognizes that both Al2O3 and CaF2 lowers the melting point of the slag and promotes the melting of the slag modifier during ladle refining, shortening the processing time (Takahashi, paragraph [0010, 0011]). Note that 1.1* 30 = 33 and 1.8*30 = 54, thus suggesting an overlapping range of CaO.
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05(I).
The combination above is quiet to the slag composition contains less than 1% SiO2 by weight.
Zhang teaches preparing a Ti containing steel, including the steps of converter smelting, adjusting slag and ladle refining, RH refining, adjusting slag, then alloying of titanium, and then casting (abstract). Zhang teaches that the slag composition after adjustment and before the titanium alloying includes SiO2 ≤ 10 wt%, and in a more preferred embodiment, SIO2 ≤ 5% (machine translation, p.3, lines 19-44). Note that SiO2 ≤ 5% encompasses the claimed range of ≤1 %.
It would have been obvious to one of ordinary skill in the art to modify the wt% of SiO2 in the slag composition of the combination, as Zhang teaches an encompassing range of SiO2 is known, and that SiO2 is not desirable in Okuyama, as Okuyama recognizes that SiO2 in the slag reacts with Ti in the molten steel to product TiO2, which then reduces the Ti yield (paragraph [0005]).
Claim(s) 16 and 31-32 is/are rejected under 35 U.S.C. 103 as being unpatentable over Krull (US 2019/0119771) in view of Okuyama and Takahashi.
Regarding claim 16, Krull teaches a method of casting a steel semi-product from a liquid steel (paragraph [0042-0043]), the steel semi-product having a targeted composition in titanium of at least 3.5% in weight (abstract, Ti: 0.55-10%, overlapping claimed range), the method comprising the following steps:
a) adding aluminum to the liquid steel so that liquid steel contains at least 0.1% by weight of aluminum (note that a step of adding aluminum is implied as the steel composition includes aluminum, abstract, Al: 6.0-25%);
c) adding titanium to the liquid steel to reach the targeted composition (note that a step of adding titanium is implied as the steel composition includes titanium, abstract, Ti: 0.55-10%); and
d) casting the steel in the form of a semi-product (paragraph [0042-0043]).
Krull is quiet to b) adding mineral compounds to the liquid steel, the mineral compounds containing CaF2 and aluminum and calcium and optionally magnesium, to reach and maintain a slag with a slag composition wherein the ratio of CaO versus Al2O3 is from 0.7 to 2 and the slag contains up to 25% by weight of CaF2, and then adding the titanium in step c).
Okuyama teaches a method for producing Ti-containing steel (paragraph [0001]) having an improved Ti yield (paragraph [0007]) by deoxidizing the molten steel in the ladle with Al (paragraph [0008]), adding a TiO2-containing substance to the slag in the ladle (paragraph [0008]), adjusting the composition of the slag so that the CaO and Al2O3 content falls within the range of 1.3 to 2.5 (paragraph [0008], overlapping the claimed range), and then Ti and/or a Ti alloy is added to the molten steel (paragraph [0008]). The materials added to adjust the slag composition include burnt lime, alumina refractory waste, alumina, aluminum ash, etc (paragraph [0016]).
As Krull teaches the final steel composition for casting, but is quiet to how said steel was produced, it would have been obvious to one of ordinary skill in the art to modify Krull so as to include the teachings of Okuyama, such as including a TiO2 containing substance to the slag in the ladle, adjusting the composition of the slag so that CaO and Al2O3 falls within the range of 1.3 to 2.5 (overlapping the claimed range) by adding mineral components including burnt lime and alumina (Okuyama, paragraph [0016]), and then adding the Titanium to the liquid steel to reach the target composition (Okuyama, paragraph [0008]), as Okuyama teaches said steps improve the Ti yield and reduce the amount of expensive Ti sources (paragraph [0007]).
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05(I).
The combination of Krull as modified by Okuyama is quiet to the slag including CaF2 up to 25% by weight.
Takahashi teaches desulfurizing molten steel tapped from a converter by ladle refining (paragraph [0001]), as sulfur in steel generally has adverse effects such as impairing the toughness of the steel (paragraph [0002]). Takahashi teaches adding a slag modifier to modify the slag composition so that Al2O3 ≥ 30%, CaF2 ≥ 5%, 1.1 ≤ CaO/Al2O3 ≤ 1.8, and CaO/SiO2 ≥ 5.0 (paragraph [0010]). Takahashi teaches that it is important that the slag composition contains 5% or more of CaF2, as CaF2 combined with the effect of adding Al2O3, further lowers the melting point of the slag, promoting the melting of the slag modifier during ladle refining, and shortening the processing time (paragraph [0011]), noting that the limit is 20% as too much CaF2 will damage the ladle refractory (paragraph [0011]).
It would have been obvious to one of ordinary skill in the art to modify the slag composition of combination so as to include 5% or more of CaF2, as taught in Takahashi, as Takahashi recognizes that CaF2 lowers the melting point of the slag and promotes the melting of the slag modifier during ladle refining, shortening the processing time (Takahashi, paragraph [0011]).
In the case where the claimed ranges "overlap or lie inside ranges disclosed by the prior art" a prima facie case of obviousness exists. In re Wertheim, 541 F.2d 257, 191 USPQ 90 (CCPA 1976); In re Woodruff, 919 F.2d 1575, 16 USPQ2d 1934 (Fed. Cir. 1990). MPEP 2144.05(I).
Regarding claim 31, the combination teaches the steel semi-product has a targeted composition in titanium of at least 8% (Krull, abstract, Ti: 0.55-10%, overlapping the claimed range).
Regarding claim 32, the combination teaches the steel semi-product has a targeted composition in titanium of 8% to 10% (Krull, abstract, Ti: 0.55-10%, encompassing the claimed range, shared end point).
Response to Arguments
Applicant's arguments filed 9/08/25 have been fully considered but they are not persuasive.
Applicant argues that the combination of references would not have led one of ordinary skill in the art to add mineral compounds to the liquid steel, the mineral compounds containing CaF2 up to 25% and aluminum and calcium in a ratio of CaO versus Al2O3 of 0.7 to 2 (p.8 of remarks).
In particular, applicant argues (p.9 of Remarks) that Barker does not disclose that CaF2 is a low melting point fluidizing material and argues that CaF2 has disadvantages that outweigh its possible usefulness as fluidizing agent. Applicant points to the melting point of CaF2 being 1423°C, which applicant argues is not a low melting point. Applicant further argues that there is no disclosure in Okuyama of its slag being solid, needing to be fluidized, or having any issues of keeping the flux layer fluid at the interface.
Barker and Labate are no longer cited in the current rejections. Applicant’s arguments directed to Barker and Labate are moot in view of the new grounds of rejection.
Takahashi is cited for teaching a slag modifier to modify a slag composition, and that the resultant slag has more than 5% CaF2. Takahashi teaches that CaF2 further lowers the melting point of the slag, thus shortening the processing time (paragraph [0010-0011]). Although applicant argues that CaF2 has a melting point of 1423°C which is not a low melting point, the melting point of CaF2 is lower than the other components of the slag (CaO/Al2O3) and is described in Takahashi as lowering the melting point of the slag. In response to applicant’s argument that Okuyama does not need the slag to be melted or fluidized, the Examiner disagrees. Okuyama adjusts the slag composition (paragraph [0008]) by adding materials such as burnt lime, alumina refractory waste, alumina, aluminum ash, etc (paragraph [0016]), which would need to be melted. Okuyama also recognizes that if the solid content of the slag increases, fluidity of the slag deteriorates and reduces the ability of desulfurization (paragraph [0015]). Takahashi’s teaching of shortening the process time is also relevant to Okuyama, as Okuyama does not want to extend the operation time (paragraph [0022]).
Regarding claim 36, applicant argues that the claims require titanium to be added to the liquid steel only after step B. Applicant argues that this limitation precludes Okuyama, who adds titanium prior to or during the Al deoxidation in the form of TiO2. The examiner disagrees. The language of the claim requires addition of titanium to the liquid steel only after step B. Okuyama adds a titanium oxide-containing material, not titanium metal or titanium alloy, prior to step B, and that the titanium oxide-containing material is added to the slag, not to the liquid steel (paragraph [0008]). Okuyama adds sponge titanium or scrap titanium to the molten steel after adjusting the slag composition (paragraph [0008], [0016]).
Regarding claim 39, applicant argues that the combined teachings would not have led one of ordinary skill in the art to the claimed crystallization rate. The examiner notes that "[T]he discovery of a previously unappreciated property of a prior art composition, or of a scientific explanation for the prior art’s functioning, does not render the old composition patentably new to the discoverer." Atlas Powder Co. v. IRECO Inc., 190 F.3d 1342, 1347, 51 USPQ2d 1943, 1947 (Fed. Cir. 1999). MPEP 2112(I).
As discussed in the rejections above, the prior art suggests the same composition of the slag, therefore the crystallization rate, which is a property of the slag, is presumed to be inherent. MPEP 2112.01. Where the claimed and prior art products are identical or substantially identical in structure or composition, or are produced by identical or substantially identical processes, a prima facie case of either anticipation or obviousness has been established. In re Best, 562 F.2d 1252, 1255, 195 USPQ 430, 433 (CCPA 1977). MPEP 2112.01(I).
Regarding claim 37, applicant argues that Okuyama adds TiO2, therefore teaching away from the claimed step of reducing TiOx content of a slag.
The examiner disagrees. Although TiO2 is added prior to the addition of aluminum to deoxidize, JP 2000-345234A shows that the additional TiO2 can be reduced by the addition of aluminum, thus meeting the claim limitation. The reduction of the TiO2 increases the amount of Ti in the molten steel. Furthermore, the amount of TiO2 in the slag of Okuyama falls within the range of TiOx disclosed by applicant, as the slag of Okuyama includes preferably 5% to 15% TiO2 (paragraph [0014]).
Regarding claim 38, applicant argues that the combination does not teach the slag composition. Note the rejections above. In particular, although Okuyama shows the slag composition having 3 to 10% SiO2, SiO2 is not desired in Okuyama’s composition and only remains due to not being sufficiently reduced (paragraph [0010]). Okuyama shows that SiO2 would react with Ti, pushing the reaction in paragraph [0011] to the right, and decreasing the yield of Ti, and suggested a step to further reduce the SiO2 by further increasing Al (paragraph [0006]). As discussed in the rejections above, Zhang teaches a slag composition where SiO2 can be less than 5%, thus encompassing the claimed range.
Conclusion
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/JACKY YUEN/
Examiner
Art Unit 1735
/KEITH WALKER/Supervisory Patent Examiner, Art Unit 1735