The weldability of new EH40 ship steel plate by submerged arc welding with high heat-input was studied by the tensile test,impact test,hardnes9 test and microstructure. The results show that the impact property of all testing positions meet the requirement at the high heat-input welding of 100 kJ/cm,125 kJ/cm and 200 kJ/em, where the impact absorbing energy in coarse gain zone was lower than that in the other positions except for weld metal. During welding,there was not obvious hardening and softening phenomenon in heat affected zone. The micro-structure in coarse grain zone transfers from ferrite and pearlite to blocky ferrite, bainite and Widmanstaten structure. The ratio of bainite and Widmanstaten structure increases with the increase of welding heat-input. The toughness in the coarse grain heat affected zone is improved for the existing carbides and nitrides of Ti and Nb, which effectively pin the original austenite boundaries and prohibit the original austenite grain from coarsening in high heat-input welding process.%通过拉伸、冲击、硬度等力学试验和焊接接头微观组织分析,对新型EH40钢板大热输入量埋弧焊的焊接性和焊接接头性能进行了分析.试验结果表明,在100 kJ/cm,125 kJ/cm和200 kJ/cm热输入量条件下焊接,各检验位置的冲击性能均满足船级社规范的要求.除焊缝检验位置以外,焊接热影响区中粗晶区位置的冲击性能均低于其它检验位置.焊接过程中,热影响区没有出现明显的硬化和软化现象.粗晶区的显微组织由铁索体和珠光体为主变为以块状铁索体、贝氏体和魏氏体组织为主,同时存在少量的粒状贝氏体和黑色的M-A组元,随着焊接热输入量的增加,贝氏体和较为粗大的魏氏体组织所占比例增大.焊接热影响区中存在大量Ti和Nb的碳氮化合物的第二相粒子,这些第二相粒子有效地钉扎原奥氏体晶界,阻碍奥氏体晶粒的长大,从而改善了焊接热影响区的低温冲击性能.
展开▼
