海洋平台用EQ70高强钢焊接性研究

Welding performance of EQ70 high-strength steel for offshore platform

采用CONARC80焊条手工电弧焊接EQ70钢,研究了焊接工艺对接头性能的影响.结果表明:在焊后热处理的条件下,其接头强度在焊接电流为180 A或200 A时,均能和母材等强;当焊接电流达到220 A时,则接头强度低于母材;EQ70钢焊接接头在室温均具有很好的冲击韧性;在150℃预热、200 A焊接电流和焊后热处理的条件下,焊接接头各区域在-40℃的冲击值最佳,达到母材的95%以上;EQ70钢焊接接头的冷弯性能均合格.焊缝硬度和母材相当,但热影响区的硬度值偏高,超过平均水平5%～10%;结合海洋平台工作环境对低温韧性的要求,推荐EQ70钢焊接工艺为150℃预热2、00 A焊接电流以及250℃/2h焊后热处理的规范.

CONARC80 electrode is used for EQ70 steel manual metal arc welding process.The research results show that in the condition of post-weld heat treatment,the joint strength is the same as the base metal in the welding current of 180 A and 200 A.When the welding current is increased to 220 A,the joints strength is smaller than the base metal.The EQ70 steel welded joints provide excellent impact ductility at room temperature.In the condition of 150 ℃ preheating treatment,200 A welding current and post-weld heat treatment,each area of the weld joints shows the best impact ductility at-40℃,and is more than 95% of the base metal.The cold bending performances of EQ70 steel weld joints are all qualified.The weld bead provides the same hardness as the base metal,but the HAZ hardness is 5%~10% more than the average.Squaring up the working environment of offshore platform requirements on low temperature toughness,recommended EQ70 steel welding process is 150 ℃ preheating treatment,200 A welding current and 250 ℃/2h post-weld heat treatment.