中文摘要：

430铁素体不锈钢在焊接时,热影响区晶粒粗化会使接头韧性下降.利用热模拟技术和焊剂带约束电弧超窄间隙焊接方法对430铁素体不锈钢进行试验,得到不同热输入下粗晶区的组织,并测试其韧性性能.结果表明：当热输入低于3kJ/cm时,粗晶区组织主要为板条贝氏体和少量针状铁素体,铁素体晶粒尺寸小于48μm,室温冲击功与母材相当.铁素体晶粒不断长大是造成冲击韧性下降的主要原因.采用超窄间隙焊接方法,可以有效缩短高温停留时间,将铁素体晶粒尺寸限制在50μm以内,从而使韧脆转变温度降低至约-30℃,避免粗晶区韧性下降.

英文摘要：

The ferritic stainless steel toughness of welded joint may be made decreased by grain coarsening in heat affected zone.The microstructure of coarse-grained zone of ferritic stainless steel with different welding heat inputs was obtained by means of experiment on 430 ferritic stainless steel with thermal simulation technique and the ultra-narrow gap welding method,and the toughness of the coarse-grained zone was tested.The result showed that when the heat input was lower than 3kJ/cm,the microstructure of coarse grain zone would mainly be lathed bainite and a little amount of acicular ferrite with grain size of less48μm,and the impact work at room temperature would be similar to that of matrix material.The main reason for the decrease of the toughness is the growth of ferritic grain.The narrow-gap welding could decrease the holding time in high temperature and limit the grain size below 50μm,so it can decrease the ductile-to-brittle transition temperature to-30℃and avoid the decrease of the toughness of coarse-grained zone.