药皮合金元素对FV520(B)钢焊缝组织和韧性的影响

Effect of Addition of Alloying Elements in Welding Flux on Microstructure and Toughness of Weld Seam of FV520(B) Steel

在焊条药皮中添加中碳锰铁和镍粉将Mn、Ni元素过渡到FV520(B)钢焊缝,用金相分析、冲击试验、XRD分析和SEM观测等手段研究了药皮合金元素对FV520(B)钢焊缝的组织和韧性的影响。结果表明:FV520(B)钢焊缝组织以回火索氏体和板条马氏体为主,出现残余奥氏体和二次析出相;随着合金元素的增加,焊缝的组织更加细小致密,马氏体片层更加均匀细小,分布更加弥散。与酸性药皮相比,碱性药皮过渡合金元素的效果更显著,因此焊缝的冲击韧性更优良。用药皮过渡Mn、Ni能提高焊缝中奥氏体的含量,进而改善FV520(B)钢焊缝的冲击韧性。与Mn相比,添加Ni提高焊缝韧性的效果更为显著。

The influence of addition of alloying elements of medium carbon Fe-Mn and Ni in the welding flux on the microstructure and toughness of the weld seam of FV520（B） steel was investigated by means of impact test, metallographic microscope, SEM and X-ray diffractometer. The results show that the microstructure of the weld seam of FV520（B） steel mainly composed of tempered sorbite and lath martensite with some residual austenite and secondary phases. With the increasing amount of alloying elements Mn and Ni, the microstructure of weld seam became finer, and the lamellae of martensite became thinner and distributed more uniformly. The addition of allying elements into a basic flux rather than an acidic ones showed much higher effectiveness in improvement of the toughness of the weld seam.The induced Mn and Ni can enhance the austenitic amount in the weld seam, which in turn plays an important role in enhancing its toughness. Moreover, the induced Ni rather than Mn was more effective in enhancing the toughness of the weld seam.