药芯焊丝镍含量对25Cr2Ni4MoV高强钢焊接接头组织与性能的影响

Effect of Ni Content in Flux-Cored Wire on Microstructure and Properties of 25Cr2Ni4MoV High Strength Steel Welded Joint

基于25Cr2Ni4MoV钢的化学成分,设计了3种不同镍质量分数(15%,19%,23%)的金属型药芯焊丝,对25Cr2Ni4MoV钢板进行熔化极活性气体保护电弧焊,研究了药芯焊丝中镍含量对接头组织与力学性能的影响。结果表明:接头焊缝组织均由板条马氏体、贝氏体及少量针状铁素体组成,随着药芯焊丝中镍含量的增加,焊缝中板条马氏体组织先细化后粗化,接头的断后伸长率和冲击吸收功增加,强度先升高后降低。当药芯焊丝中镍质量分数为19%时,接头的抗拉强度达到最高,为920 MPa,冲击吸收功为48 J,此时接头具有较好的强韧性匹配。

Based on the chemical composition of 25Cr2Ni4MoV steel, three metal flux-cored wires with different nickel mass fractions(15%,19%,23%) were designed, and then the 25Cr2Ni4MoV steel plate was welded by metal active gas shielded arc welding. The effect of Ni content in the flux-cored wire on the microstructure and mechanical properties of the joint was studied. The results show that the weld microstructures of the joints were all composed of lath martensite, bainite and a small amount of acicular ferrite. With the increase of Ni content in the flux-cored wire, the lath martensite structure in the weld was refined first and then coarsened;the elongation and impact absorption energy of the joint increased, and the strength increased first and then decreased. When the mass fraction of Ni in the flux-cored wire was 19%, the tensile strength of the joint reached the highest value of 920 MPa, and the impact absorption energy was 48 J;the joint had good matching of strength and toughness.