2205双相不锈钢焊接热影响区的组织转变行为

Transition behavior of welding HAZ microstructure of 2205 duplex stainless steel

通过焊接热模拟方法和现代材料组织分析技术,研究了冷却时间t8/5和t12/8对2205双相不锈钢模拟热影响区(HAZ)组织转变行为的影响。结果表明,固定t12/8,改变t8/5,2205双相不锈钢模拟HAZ的组织形态和相比例相差不大,用t8/5作为参数研究这种材料HAZ组织转变行为是不恰当的;固定t8/5,改变t12/8,2205双相不锈钢模拟HAZ的组织形态和相比例变化比较大,t12/8是影响这种材料HAZ组织的本质因素,用它来研究对2205双相不锈钢HAZ组织的影响更为确切。冷却时间t12/8对2205双相不锈钢模拟HAZ组织的影响规律是,随着t12/8的增加,奥氏体由原来的长条状逐渐变成树枝状,晶界和晶粒内部均析出奥氏体,相互交集在一起形成网状。铁素体的比例随着冷却时间t12/8的增加而缓慢下降;2205双相不锈钢模拟HAZ组织中奥氏体和铁素体晶内比母材有更多的位错。

Thermal simulation technology and modern material microstructure analysis method are adopted to research the effect of cooling time t8/5 and t12/8 on the simulated HAZ(heat-affected zone) microstructure transition in 2205 duplex stainless steel. The results indicate that keeping t12/8 constant and changing t8/5, the simulated HAZ microstructure and phase proportion almost keep same. So it is not suitable to this material to use t8/5 as the parameter to investigate the transition behavior of welding HAZ microstructure. When the cooling time t8/5 keeps constant and t12/8 is changed, the simulated HAZ microstructure and phase proportion vary largely. Therefore, t12/8 is the essential factor to affect HAZ microstructure, and it is more suitable to use t12/8 as the parameter to investigate the transition behavior of welding HAZ microstructure. The effect of the cooling time t12/8 on the simulated HAZ microstructure is, when t12/8 increases, austenite gradually transits to branch-like morphology from band-like distribution and appears at the boundary and inside the grain. On the other hand, the ferrite content decreases with the cooling time t12/8 increasing. In this case, austenite and ferrite in the simulated HAZ microstructure of 2205 contain more dislocation than the base metal.