Zr含量对大热输入焊缝金属组织及冲击韧性的影响

Effect of Zirconium Contents on Microstructure and Impact Toughness of Weld Metal with High-heat Input

采用气电立焊大热输入焊接方法,制备了3种不同Zr含量的焊缝金属,研究分析了Zr含量对大热输入焊缝金属组织与冲击韧性的影响。结果表明:在185 kJ/cm大热输入焊接条件下,Zr的质量分数为0.12%的1号焊缝金属中夹杂物数量有限,形成了大量粗大的等轴铁素体晶粒,不利于冲击韧性的提高;Zr的质量分数为0.35%的2号焊缝金属中夹杂物数量明显增加,形成了致密的针状铁素体(AF)组织,大幅度提升了焊缝金属的冲击韧性;Zr的质量分数为0.66%的3号焊缝金属中Zr的固溶量增加,提高了焊缝金属的淬透性,导致相变温度降低,促进了贝氏体的生成,恶化了焊缝金属的冲击韧性。

Three types of weld metal with different zirconium contents were fabricated by using gas-electric vertical welding process with high-heat input,and the effects of Zr contents on microstructure and impact toughness of the weld metal under high-heat input were investigated.The results indicated that under the condition that the welding heat input was as great as 185 kJ/cm,the inclusions in the weld metal No.1 with Zr content of 0.12%by mass were limited,resulting in a large number of coarse equiaxed ferrite grains,which was not conducive to the improvement of impact toughness.The number of inclusions in the weld metal No.2 with Zr content of 0.35%by mass increased significantly,resulting in dense acicular ferrite(AF),which greatly improved the impact toughness of weld metal.The zirconium content in solid solution in the weld metal No.3 with Zr content of 0.66%by mass increased,which improved the hardenability of weld metal,reduced the transformation temperature,promoted the formation of bainite and deteriorated the impact toughness of weld metal.