超厚板DH40船用钢焊接热影响区韧性研究
Study on HAZ Ductility of Ultra-thickness DH40 Ship Building Steel
岑 越1， 王 欢1， 吴铭方2， 陆雪冬2
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作者单位：（1.沪东中华造船（集团）有限公司，上海 200129；2.江苏科技大学，江苏 镇江 212003）
中文关键字： DH40钢；超厚板； 多层多道焊；组织；韧性
英文关键字：DH40 steel; ultra-thickness plate; multi-pass welding; microstructure; ductility
中文摘要： 采用SAW焊接方法，使用多层多道焊接技术对超厚板DH40船用钢进行了焊接性试验，重点探讨了热影响区微观组织与接头冲击性能之间的内在联系。结果表明，熔合线外5 mm区域的冲击性能较其它部位低的原因在于多层多道焊最后一次焊接热循环作用下，由于“组织遗传”作用，出现晶粒粗大造成的；焊缝根部熔合线外5 mm区域冲击性能严重衰减是由于该区域出现了大量粒状贝氏体。改善焊接工艺或进行焊后热处理，使M-A组元分解成铁素体和碳化物是提高其韧性的有效方法。
英文摘要：The weldability experiment of DH40 ship building steel was conducted by SAW in the case of the multi-pass welding technology, and the interrelationship between structure of heat-affected zone and joint impact ductility was discussed. The results show that the impact ductility in the zone of 5 mm distance to bond line is lower than other zones, and the reason is that the effect of structure heredity which result in the creation of the coarse crystal grain in the last welding thermal cycle. But the basic reason for the impact ductility in the zone of 5 mm distance to bond line of welded seam root decreasing was that the much granular binate was created. The impact ductility value is different from the shape, quantity, size and distribution of M-A component in the binate. The effective method to improve the impact ductility of this zone is to change the welding process and conduct post-weld heat treatment, which is help to divide M-A component into ferrite and carbide.