620 MPa-grade high-strength steel with cold crack sensitivity coefficient smaller than or equal to 0.19 and production method of 620 MPa-grade high-strength steel

• Main Authors: ZHANG QINGLONG, WEI XIAN, XU BO, LI NA, SONG LIWEI, CHEN YINZE, HUANG ZHONG, WANG XINZHI, SUN BIN, XU DANGWEI, ZHAO LIANGSHENG, SUN ZHIYUAN, LOU JUNKUI
• Format: Patent
• Language: Chinese; English
• Published: 13.05.2022
• Subjects: ALLOYS; CHEMISTRY; FERROUS OR NON-FERROUS ALLOYS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUSMETALS OR ALLOYS; MAKING METAL MALLEABLE BY DECARBURISATION, TEMPERING OR OTHERTREATMENTS; METALLURGY; METALLURGY OF IRON; MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; TREATMENT OF ALLOYS OR NON-FERROUS METALS

The invention provides 620 MPa grade high-strength steel with the cold crack sensitivity coefficient smaller than or equal to 0.19. The 620 MPa grade high-strength steel comprises, by weight, 0.06%-0.08% of C, 0.12%-0.50% of Si, 1.50%-1.85% of Mn, smaller than or equal to 0.020% of P, smaller than or equal to 0.010% of S, 0.20%-0.60% of Cr, 0.015%-0.060% of Nb, 0.010%-0.060% of Alt, 0.008%-0.035% of Ti, smaller than or equal to 0.005% of B, smaller than or equal to 0.08% of Mo, smaller than or equal to 0.15% of Ni, smaller than or equal to 0.15% of Cu, smaller than or equal to 0.19% of Pcm and the balance Fe and inevitable impurities. According to the production method, precious metal Mo, Ni, Cu and V are not added in the component design, the effects of C, Mn, Cr and B elements are fully played, the structure is refined through the controlled rolling and three-stage controlled cooling process and the tempering process, and the 620 MPa-grade high-strength steel with the cold crack sensitivity coefficient smal