Cr15Mn9Ni1N不锈钢焊接接头的组织及凝固模式

Microstructure and Solidification Mode of Welding Joint of Cr15Mn9Ni1N Stainless Steel

分析了Cr15Mn9Ni1N奥氏体不锈钢钨极氩弧焊接头的组织。结果表明:在靠近熔合线的热影响区,经过高温焊接热循环后析出较多的δ铁素体,大线能量时其范围增大;靠近熔合线焊缝金属的组织为奥氏体胞晶中分布着残留蠕虫状δ铁素体;焊缝中心区域为奥氏体树枝晶中分布着残留骨架状δ铁素体;大线能量接头的熔合线处的组织为奥氏体晶粒上分布侧板条形δ铁素体,而小线能量时为奥氏体晶粒。分析认为:焊缝金属的凝固模式为δ铁素体先从液相中析出,随后通过固态相变转变为奥氏体,未转变的残留δ铁素体以蠕虫状、骨架形或侧板条的形态分布于奥氏体中。Hammar-Svensson Cr、Ni当量公式适于预测这种钢焊缝金属的凝固模式。

： Microstructure of Crl 5Mn9Ni1N stainless steel joint obtained by TIG welding were analyzed. Due to the high temperature of welding heat cycle, the amount of B ferrite increase in the HAZ near the fusion line, the size of the HAZ is larger with the higher heat input. Cellular austenite matrix with vermicular residual 8 ferrite is observed in the weld metal near fusion line; dendritic austenite matrix with skeletal residual 8 ferrite is observed in the central welds. Austenite matrix with lathy 8 ferrite is observed in the fusion zone with the higher heat input; single phase austenite grains are observed in the fusion zone with the lower heat input. The solidification mode of weld metal is as follows, primary 8 ferrite solidifies from liquid metal and transforms as austenite during the subsequent solid-state transformation, and residual 8 ferrites are distributed in austenite matrix with the vermicular, skeletal or lathy morphologies. Hammar-Svensson Cr and Ni equivalent formulas are available for predicting solidification mode of the weld metal.