| 摘要 |
A steel sheet comprising, in wt%, 0.04= C= 0.30, 0.5= Mn= 4, 0= Cr= 4, 2.7= Mn+Cr= 5, 0.003= Nb= 0.1 0.015= A1= 0.1 and 0.05= Si= 1.0, has a chemistry that makes hot formed sheet after austenization insensitive to cooling rate and ensures a uniform distribution of tensile strength, in the range of 800-1400 MPa, across parts independent of the time delay between operations and final cooling/quenching. As a result, a formed part can be cooled while inside a die or in air. The addition of Nb reduces the amount of C needed to achieve a given tensile strength and improves weldability. |
