正火钢Q370qE焊接工艺研究

Study on Welding Process of Normalizing Steel Q370qE

以50 mm厚的Q370qE正火钢板为研究对象,通过一系列埋弧焊接试验,利用显微组织分析法、成分测量法和夹杂物统计法等,分析了坡口形式和角度、焊接材料和热输入对焊缝和熔合线（FL）＋1 mm低温冲击韧性的影响。结果表明：坡口形式和角度对焊缝低温冲击韧性没有影响;对于FL＋1mm的低温冲击韧性,X型坡口优于K型坡口,且X型坡口角度越大,冲击韧性越好。焊接材料对焊缝和FL＋1 mm的低温冲击韧性都有影响,随着焊剂碱度增加,焊缝中氧含量减小,夹杂物的数密度减小,形成较少的晶界铁素体,同时夹杂物的平均尺寸增大,形成更多的针状铁素体,焊缝和FL＋1 mm的冲击韧性高;降低热输入可以增加焊缝和FL＋1 mm的低温冲击韧性。

Taking the normalizing steel Q370qE plate with thickness of 50 mm as the object, through a series of submerge-arc welding（SAW） tests, the effects of groove shape and angle, welding material and heat input on the low temperature impact toughness of weld metal and FL＋1 mm were analyzed by means of microstructure analysis, composition measurement and inclusion statistics, etc. The results show that groove shape and angle have no effect on the low temperature impact toughness of weld metal. For low temperature impact toughness of FL＋1 mm, X groove is better than K groove, and the bigger the X groove angle is, the better the impact toughness is. Welding material has influence on the low temperature impact toughness of the weld metal and FL＋1 mm. With the flux alkalinity increasing, the oxygen content in weld metals decreases,the number density of inclusions decreases and smaller amount of grain boundary ferrite forms, and average size of the inclusions increases, more acicular ferrite forms. Therefore, the impact roughness of the weld metal and FL＋1 mm is high.Decreasing the heat input can increase the low temperature impact toughness of weld metal and FL＋1 mm.