00Cr18Ni10N不锈钢点焊接头显微组织及凝固模式的分析
Microstucture and Solidification Mode of Joint of 00Cr18Ni10N Austenitic Stainless Steel by Spot Welding
李鹏雁， 张 勇， 郭连志， 谢红霞
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作者单位：（西北工业大学 陕西省摩擦焊接重点实验室，陕西 西安 710072）
中文关键字：点焊接头组织； 00Cr18Ni10N； 冷却速度； 凝固模式； 显微硬度
英文关键字： structure of spot welded joint; 00Cr18Ni10N; cooling rate; solidification mode; microhardness
中文摘要：分析了00Cr18Ni10N奥氏体不锈钢点焊接头的显微组织，利用WRC-1992相组分图计算出Creq /Nieq当量比值，通过显微硬度测定值判断了铁素体的析出情况，并估算了点焊的冷却速度。显微组织分析结果表明：在不考虑冷却速度的影响下，通过相组分图的预测，点焊熔核的凝固模式为铁素体加奥氏体模式（FA）。然而，在点焊特殊工艺下，熔核组织由树枝晶和胞状晶组成，可见快速冷却改变了熔核的凝固模式，促使FA模式向AF模式和A转变。硬度测定结果表明：熔核区域的硬度比母材的低。熔核区域的硬度值几乎相同，但由于铁素体在某些区域沿枝晶轴析出，熔核区域的硬度值略有波动。
英文摘要：The microstructure of joint of 00Cr18Ni10N austenitic stainless steel by spot welding was analyzed, WRC-1992 phase composition diagram was used to calculate the ratio of Creq /Nieq, the precipitation of ferrite was determined by microhardness, and the cooling rate was estimated. The results show that the solidification of spot nugget is ferrite and austenite(FA) by phase composition diagram without considering the influence of cooling rate, however, at the special process of spot welding, the nugget consists of dendrite and cellular crystal due to the rapid cooling which changes the cooling pattern from FA to AF and A. The hardness of nugget is less than that of base metal and the hardness in nugget is almost equal, but has a little fluctuation as some ferrite precipitates along dendrite lines.