等温时间对60Si2Mn钢下贝氏体组织性能的影响

Influence of isothermal time on microstructure and properties of low bainite in 60Si2Mn steel

通过热模拟实验和盐浴淬火处理,研究了60Si2Mn钢盘条奥氏体化后在300℃等温盐浴淬火时的组织演变规律及相应的力学性能,结果表明:在300℃等温盐浴淬火,形成下贝氏体,相变孕育期约为100 s,相变完成时间约为3000 s。随等温时间延长,材料抗拉强度缓慢降低,而面缩率不断增加,等温3000 s后,材料抗拉强度保持在1800 MPa以上,面缩率可达到50%。组织分析结果显示,下贝氏体由针状铁素体和纳米级条状奥氏体组成,起到提高材料韧性的作用。

Microstructure and mechanical properties of 60Si2 Mn steel wire rod during isothermal quenching at 300 ℃ after austenizing were investigated by thermal simulation and salt-bath quenching,in combination with OM,SEM,TEM,X-Ray and tensile tests. The results show that low bainite in the tested steel can be formed during isothermal quenching at 300 ℃,the time during incubation period and finish period of bainite transformation is about 100 s and 3000 s,respectively. With increasing isothermal time,the tensile strength of the steel is slowly reduced and the reduction of area is increased continuously. When the isothermal time is up to 3000 s and more,the tensile strength can be more than 1800 MPa and the reduction of area can be up to 50%. The microstructure analysis indicates that low bainite in the steel consists of needle-like bainitic ferrite and nano-scaled bar-like austenite,resulting in the enhancement of the higher ductility of the tested steel.