DETAILED ACTION
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.
Claim(s) 1-7 and 9-16 is/are rejected under 35 U.S.C. 103 as being unpatentable over Blaise et al. (2020/0399734) in view of Abukawa et al. (11,505,846). Regarding claim 1, Blaise discloses performing a hot stamping ([0107], lines 1-3) on a pre-coated steel plate matrix ([0065],[0066]) using a die (press tooling in a forming press) at a hot stamping temperature (850-1000°C; [0101], line 5) to obtain a hot stamped component (part; [0107], line 6). Blaise discloses performing a preliminary heat treatment on the pre-coated steel plate matrix (non-stamped pre-coated steel sheet; [0070], lines 1-3) before the hot stamping, the preliminary heat treatment comprising (1) heating the pre-coated steel plate matrix to between 750- 1000°C [0071] for a time duration of t1min to t1max [0073] wherein for a temperature of 920°C, t1min is about 2 minutes and t1max is about 14 minutes and (2) cooling the pre-coated steel plate matrix to below 300 °C [0094] after the step of heating and temperature holding ([0082],[0083]) at a cooling rate not less than 5 °C/s (10°C/s; [0083], line 8). Regarding the preliminary heat treatment step (3), it is claimed as optional so it not a required step and it not read as a required part of the process, but it presents a scope of multiple heating and cooling steps. Blaise does not specifically recite that the cooling rate is greater than 10°C/s.
Abukawa teaches in a hot stamping forming method for a pre-coated steel plate, performing hot stamping on a pre-coated steel plate by using a die, performing a preliminary heat treatment on the pre-coated steel plate, wherein the first heat treatment is heating the pre-coated steel plate to 900-1200°C (col. 10, lines 1-5) and maintaining the temperature for 100-600 seconds (col. 10, lines 22-26) so that a pre-coated steel plate substrate is austenitized and cooling after the heating and temperature maintaining step is completed, to 250°C or less (col. 11, lines 2-4), wherein gas cooling or water cooling is used for cooling the pre-coated steel plate from a first temperature to 700°C, and when the pre-coated steel plate is cooled from 700°C to 500°C, the average cooling speed is 10 °C/s or above (col. 10, lines 32-36). The original austenite grain size of the substrate structure obtained after hot-stamping forming is performed is 10 µm or less (col. 4, line 25). It would have been obvious to the skilled artisan prior to the effective filing date of the present invention to increase the cooling rate in the cooling of Blaise to a rate of 10 °C/s or above as taught by Abukawa so that a ferrite, bainite and pearlite transformation is less likely to occur in the cooling temperature range of 700°C to the martensitic transformation temperature and below 500°C.
Regarding claim 2, Blaise discloses [0061] that in addition to ferrum (Iron), the pre-coated steel plate matrix comprises the following composition represented by weight percentage: carbon 0.2-0.4% (Blaise discloses carbon 0.15-0.5%); manganese 0.5-1.5% (Blaise discloses 0.5-3% Manganese); boron 0-0.005% (Blaise discloses 0- 0.01% Boron) and one or more alloying element(s) not more than 1%, selected from aluminum (Blaise discloses Aluminum less than or equal to 0.1%), silicon, chromium, molybdenum, niobium, vanadium; and other inevitable impurities. Blaise discloses that the pre-coated steel plate matrix is between 0.5-5 mm [0034].
Regarding claims 3 and 11-13, Blaise discloses that the pre-coating layer of Al-Si ([0066], lines 3-5) has a thickness of between 20-70 µm [0068].
Regarding claim 4, Blaise discloses a thickness of between 20-70 µm [0068] and a holding temperature between 750-1000°C wherein for a for a temperature of 920°C, t1min is about 2 minutes and t1max is about 14 minutes.
Regarding claim 5, Blaise discloses a stamping die for press cooling [0044].
Regarding claim 6, Blaise does not disclose that the steel sheet has no carbide grains greater than 0.5 µm. Abukawa teaches (col. 9, lines 19-28) that a cooling (first quenching) is performed on a steel sheet so that an average carbide grain diameter is 0.5 µm or less and that a total area fraction of bainite and martensite is 80% or more and the proportion of a pearlite colony (col. 9, lines 25- 26) does not have coarse grains with an average grain diameter of 0.5 µm or less (col. 9, lines 44-45). Abukawa teaches that the cooling rate in the temperature zone from 700°C to 500°C (col. 10, lines 33-37) is 10°C/s or greater. Blaise discloses [0083] that the cooling rate of 10° C/s transforms the steel microstructure to have area fractions of bainite and martensite with less than 30% but it is obvious as taught by Abukawa that a cooling rate greater than 10° C/s in the temperature range from 700°C to 500°C generates a greater area fraction of bainite and martensite with finer carbide grains and it is an obvious modification to conduct routine experimentation with cooling rates greater than 10° C/s as taught by Abukawa to fine the grains of the steel sheet of Blaise.
Regarding claim 7, Blaise discloses an FeAl microstructure ([0031], lines 6-10) wherein the steel sheet has a ferrite-pearlite microstructure [0023] of about 70% since the bainite and martensite is controlled to be less than 30% [0022].
Regarding claim 9, Abukawa teaches bainite and martensite after hot stamping (col. 9, lines 28-30).
Regarding claim 10, Blaise does not disclose that the microstructure after hot stamping has an austenite grain size not greater than 18 µm. Abukawa teaches that an austenite grain diameter of a stamped part is 20 µm or less (col. 5, lines 1-4 and col. 12, lines 45-49). It would have been obvious to the skilled artisan prior to the effective filing date of the present invention to repeat cooling times in the heat treatment of Blaise as taught by Abukawa in order to refine the grain size of the austenite to be at least 20 µm or less to obtain sufficient fracture toughness of the stamped part.
Regarding claim 14, Abukawa teaches a cooling rate of greater than 20°C/s (col. 11, lines 57-60) and teaches that an upper cooling limit is 500°C/s for in-die cooling (col. 12, line 12).
Regarding claim 15, Abukawa teaches that the original austenite grain size of the substrate structure obtained after hot-stamping forming is performed is 10 µm or less (col. 4, line 25)
Regarding claim 16, Blaise discloses that after press forming and cooling the microstructure is fully martensitic ([0119], lines 4-5).
Allowable Subject Matter
Claim 8 is objected to as being dependent upon a rejected base claim, but would be allowable if rewritten in independent form including all of the limitations of the base claim and any intervening claims. The prior art of record does not disclose that he method further comprises after the preliminary heat treatment, reheating the pre-coated steel plate matrix to 780 - 940 °C and holding the temperature for 1 to 7 minutes, for completely austenitizing the pre-coated steel plate matrix; then keeping the temperature above 500 °C and transferring the pre-coated steel plate to the die for hot stamping and after the preliminary heat treatment, reheating the pre-coated steel plate matrix to 830 - 900 °C and holding the temperature for 1 to 4 minutes, for completely austenitizing the pre-coated steel plate matrix; then, keeping the temperature above 600 °C and transferring the pre-coated steel plate matrix to the die for hot stamping, including the limitations of base claim 1. It is noted that if the claim 8 steps are incorporated into claim 1, the “optionally” step (3) at the end of claim 1 needs to be deleted since actual further heating steps would be positively claimed.
Response to Arguments
Applicant's arguments filed 5-11-2026 have been fully considered. It is not clear to the Examiner how Blaise is argued as being not the same scope of the present invention claim 1, Applicant is arguing a single heating step in the process (page 7, last paragraph) but claim 1 recites, optionally, that any of the above method steps are repeatable which is a scope of a plurality of processes and a plurality of heating steps, the argument that Blaise is two step heating and Applicant is one heating is not commensurate with a scope of claim 1. Applicant has amended to 10°C/s or more and Abukawa teaches that a commercially conducted cooling step is up to a cooling rate of 500°C/s (col. 12, line 12). Abukawa teaches that the cooling rate in the temperature zone from 700°C to 500°C (col. 10, lines 33-37) is 10°C/s or greater and the cooling step is specifically recited to be more 10°C/s or more (col. 11, lines 57-60) and a cooling stop temperature is 250°C.
Conclusion
Applicant's amendment necessitated the new ground(s) of rejection presented in this Office action. Accordingly, THIS ACTION IS MADE FINAL. See MPEP § 706.07(a). Applicant is reminded of the extension of time policy as set forth in 37 CFR 1.136(a).
A shortened statutory period for reply to this final action is set to expire THREE MONTHS from the mailing date of this action. In the event a first reply is filed within TWO MONTHS of the mailing date of this final action and the advisory action is not mailed until after the end of the THREE-MONTH shortened statutory period, then the shortened statutory period will expire on the date the advisory action is mailed, and any nonprovisional extension fee (37 CFR 1.17(a)) pursuant to 37 CFR 1.136(a) will be calculated from the mailing date of the advisory action. In no event, however, will the statutory period for reply expire later than SIX MONTHS from the mailing date of this final action.
Any inquiry concerning this communication or earlier communications from the examiner should be directed to EDWARD THOMAS TOLAN whose telephone number is (571)272-4525. The examiner can normally be reached M-F 7:30-5.
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/EDWARD T TOLAN/Primary Examiner, Art Unit 3725
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