An ultrafine lamellar-structured martensite steel fabricated by heavy warm rolling(HWR)has shown an excellent combination of strength and ductility.By appending tempering at 400℃to HWR,we show that the comprehensive ...An ultrafine lamellar-structured martensite steel fabricated by heavy warm rolling(HWR)has shown an excellent combination of strength and ductility.By appending tempering at 400℃to HWR,we show that the comprehensive mechanical property of a lamellar-structured low-carbon martensite steel can be further improved to reach a yield strength of~1.8 GPa,an ultimate tensile strength of~2.0 GPa and a total elongation of~9.3%.This is achieved by tempering the HWR steel from 300 to 750℃,and the optimum tempering temperature is thus obtained.We find that the tempered ultrafine lamellar martensite contains high-density nanoprecipitates dispersed within the aligned martensite laths with reduced crystallographic variations.The ultrahigh strength of the steel is rationalized as mainly the result of grain boundary strengthening and precipitation strengthening,which contribute to yield stress by 610 MPa and 440 MPa,respectively.The good ductility is believed to be closely related to the capacity of the tempered grains to accommodate dense dislocations upon plastic deformation.The present thermomechanical processing provides a feasible routine for producing steels with ultrahigh-strength and good-ductility.展开更多
基金funded by the National Natural Science Foundation of China(No.52071212)supported by the Innovation Program of the Shanghai Municipal Education Commission(No.2019-01-07-00-09-E00024)BAOSTEEL-SJTU Joint Research Center for Future Steel。
文摘An ultrafine lamellar-structured martensite steel fabricated by heavy warm rolling(HWR)has shown an excellent combination of strength and ductility.By appending tempering at 400℃to HWR,we show that the comprehensive mechanical property of a lamellar-structured low-carbon martensite steel can be further improved to reach a yield strength of~1.8 GPa,an ultimate tensile strength of~2.0 GPa and a total elongation of~9.3%.This is achieved by tempering the HWR steel from 300 to 750℃,and the optimum tempering temperature is thus obtained.We find that the tempered ultrafine lamellar martensite contains high-density nanoprecipitates dispersed within the aligned martensite laths with reduced crystallographic variations.The ultrahigh strength of the steel is rationalized as mainly the result of grain boundary strengthening and precipitation strengthening,which contribute to yield stress by 610 MPa and 440 MPa,respectively.The good ductility is believed to be closely related to the capacity of the tempered grains to accommodate dense dislocations upon plastic deformation.The present thermomechanical processing provides a feasible routine for producing steels with ultrahigh-strength and good-ductility.
基金financially supported by the National Science Foundation of China(52322101,92163215,51731006,51771093,52174364,52101143,52305379)the National Key R&D Program of China(2021YFA1200201)the Fundamental Research Funds for the Central Universities(30922010202)。
