热输入对Q1100钢焊接接头低温韧性及耐蚀性能的影响

Effect of Heat Input on Low Temperature Toughness and Corrosion Resistance of Q1100 Steel Welded Joints

采用10 kJ/cm和15 k J/cm两种焊接热输入对Q1100超高强钢进行熔化极气体保护焊,研究焊接接头的组织性能及局部腐蚀行为。结果表明:两种热输入焊接接头的焊缝组织主要为针状铁素体和少量的粒状贝氏体,粗晶区组织均为板条贝氏体,细晶区组织均为板条贝氏体和粒状贝氏体,临界相变区组织为多边形铁素体、马奥岛和碳化物的混合组织。两种热输入焊接接头中电荷转移电阻均为母材>热影响区>焊缝区,母材耐蚀性最好,热影响区次之,焊缝区耐蚀性最差。在腐蚀过程中,焊缝区作为阳极最先被腐蚀,当腐蚀一定时间后,腐蚀位置发生改变,阳极腐蚀区域转移到母材区,而焊缝区作为阴极得到保护。热输入为10 k J/cm时,焊接接头具有更好的低温韧性和耐蚀性,其焊缝和热影响区-40℃冲击功分别为46.5 J和30.2 J。

Welded joints of Q1100 ultra high strength steel were made via gas shielded arc welding with welding heat inputs of 10 kJ/cm and 15 kJ/cm respectively.The microstructure,mechanical properties and local corrosion behavior of welded joints were studied.The results show that the microstructure of weld zone for the two welded joints is mainly acicular ferrite and a small amount of granular bainite.The microstructure is lath bainite for the coarse grain zone,and lath bainite and granular bainite for the fine grain zone of the weld joints.The microstructure of the critical phase transition zone is a mixture of polygonal ferrite,Mayo islets and carbide.The charge transfer resistance of various portions of the two welded joints could be ranked as the following order:base metal>heat affected zone>weld zone.The base metal had the best corrosion resistance,followed by the heat affected zone,and the weld zone had the worst corrosion resistance.During the corrosion process,the weld zone was first corroded as an anode.After a certain time of corrosion,the corrosion position changed,and the anode corrosion area was transferred into the base metal,while the weld zone was protected as a cathode.The welded joint with heat input of 10 kJ/cm has better low temperature toughness and corrosion resistance.The impact energies are 46.5 J and 30.2 J for the weld zone and heat affected zone respectively at-40℃.