奥氏体不锈钢储能焊接头组织形成规律

Microstructural formation of austenitic stainless steel joint by capacitor discharge welding

摘要: 采用微型储能焊机对厚度为0.2 mm的0Cr18Ni9奥氏体不锈钢薄板进行了点焊连接研究,理论分析了微型熔核的温度场和冷却速率.结果表明,微型接头由熔核区和熔合区组成.极短的焊接时间,高的冷却速率5.1×10⁶K/s,使得熔核中奥氏体组织来不及长大,熔核凝固组织得到显著细化,具有快速凝固特征;同时,熔核中奥氏体组织在敏化温度区停留时间很短,抑制了铬在奥氏体晶界上的析出.当储能焊接电压为80V、电容为6 600μF、电极力为18 N时,可获得综合性能优良的高质量点焊接头.

Abstract: The 0Cr18Ni9 austenitic stainless steel sheet with 0.2 mm thickness was welded in capacitor discharge spot welding.The temperature field and cooling rate of nugget was calculated.The results show that the joint microstructure consists of nugget zone and semi-melt zone.Due to very short time in welding, the cooling rate of the joint reaches to 5.1×10⁶ K/s, the growth of austenite microstructure is impeded, and the microstructure of the nugget is refined, which has rapidly solidified characteristics.As the austenite microstructure of the nugget stays in temperature province of activation with very short time, the chrome of austenite grain boundary precipitations is checked.To obtain the high quality spot-weld joint, the welding parameters are determined as: welding voltage 80 V, capacitor 6 600 μF and electrode pressure 18 N.