Effect of Isothermal Heat Treatment on Microstructure and Mechanical Properties of a MediumCarbon Ultra High Strength Spring Steel
NIE Yihong1,2,HUI Weijun2,FU Wantang1,WENG Yuqing２,3，DONG Han2
1. State Key Labour of Metastable Material Science and Technology, Yanshan University, Qinhuangdao 066004, Hebei, China；2. National Engineering Research Center of Advanced Steel Technology, Beijing 100081, China； 3. The Chinese Society for Metals, Beijing 100711, China
Abstract：The effect of isothermal heat treatment on microstructure and mechanical properties of a mediumcarbon ultra high strength spring steel (U) was studied. The results show that a carbidefree bainite/martensite duplex microstructure could be obtained by austempering at 325375 ℃. The austenitizing temperature before austempering has obvious influence on both the microstructure and mechanical properties of bainite/martensite duplex microstructure of steel U. With increasing austenitizing temperature from 875 ℃ to 930 ℃, the strength of steel U increases, while its toughness decreases markedly. Bainite/martensite duplex microstructure with good combination strength and toughness was obtained by austempering at 325 ℃ for 120 s after austenitizing for 30 min at 875 ℃ followed by tempering at 300 ℃ for 2 h.The fracture toughness of specimens was 83 MPa·m1/2,1.5 times higher than that of single tempered martensite with same strength level.
聂义宏;惠卫军;傅万堂;翁宇庆;董瀚. 等温处理对中碳超高强度弹簧钢组织与力学性能的影响[J]. 钢铁, 2008, 43(4): 75-0.
NIE Yihong;HUI Weijun;FU Wantang;WENG Yuqing;DONG Han. Effect of Isothermal Heat Treatment on Microstructure and Mechanical Properties of a MediumCarbon Ultra High Strength Spring Steel. Iron and Steel, 2008, 43(4): 75-0.
2008, Vol. 43 
