Ni对金属粉芯型焊丝接头性能的影响

Effect of Ni on properties of welded joint prepared with metal powder flux cored wire

为了制备WQ960高强钢焊接所需的药芯焊丝,自行研制了Mn-Mo-Cr系金属粉芯型药芯焊丝,并在药芯中添加Ni粉来改善焊接接头的冲击韧性.利用拉伸试验、硬度试验和冲击试验等测试方法研究了Ni元素对焊接接头力学性能的影响.结合组织观察和化学成分分析方法,从组织结构的角度对Ni元素的影响机理进行了合理解释.结果表明,随着焊缝中Ni含量的增加,焊接接头的抗拉强度增大,但伸长率减小.当温度为-60~25℃时,焊缝冲击功呈现先增大后降低的趋势.随着Ni含量的增加,焊缝及热影响区硬度增大,焊缝最高硬度值为329. 5 HV,热影响区软化现象有所缓解.焊缝金属中加入适量的Ni元素具有提高焊接接头冲击功的作用,且最佳Ni含量为1. 22%.

In order to fabricate the flux cored wire required in welding the WQ960 high strength steel,the Mn-Mo-Cr system metal powder flux cored wire was self-developed,and the Ni powder was added into the flux core to improve the impact toughness of welded joint.The effect of Ni element on the mechanical properties of welded joint was studied through performing the tensile test,hardness test and impact test.Combined with both microstructure observation and chemical composition analysis,the effect mechanism was reasonably explained from the perspective of microstructure.The results show that with increasing the Ni content in the weld line,the ultimate tensile strength of welded joint increases,but the elongation decreases.When the temperature is in the range from-60℃to 25℃,the impact energy of weld line firstly increases and then decreases.With increasing the Ni content,the hardness of both weld line and heat affect zone increases,and the maximum hardness value of weld line is 329.5 HV.Meanwhile,the softening phenomenon of heat affected zone gets alleviated.It shows that the addition of suitable amount of Ni element into the weld metal plays a role of increasing the impact energy of welded joint,and the optimum addition amount of Ni is 1.22%.