锆对X70钢焊缝微观组织及韧性的影响

Influence of Zirconium Content on Microstructure and Toughness of X70 Steel Weld Metal

通过在埋弧焊焊剂中添加铁锆合金粉末,以此向焊缝金属过渡锆元素.研究了金属锆对X70钢焊缝金属微观组织和性能的影响。结果表明。锆的加入增加了焊缝金属中针状铁索体的含量,改善了焊缝金属的微观组织。夏比冲击韧性试验显示,锆含量在0.006%时焊缝金属韧性最好。超过0.006%,焊缝金属中虽然也保持了较高的铁索体含量,但由于出现了小岛状的M-A组元,导致韧性降低。

Zirconium was transferred from the flux to the weld metals through adding Fe-Zr alloy in the weld flux. The influence of zirconium on microstructure and toughness of X70 steel weld metal was studied. The results show that the addition of Zr increases the content of acicular ferrite and improves the microstructure of weld metal. The results of Charpy-V tests have displayed that the weld metal obtains the best toughness at a content of 0.006 wt, % of Zr. Above the level, although the weld metal still obtains a relative high content of acicular ferrite, due to the formation of island-like martensite-austenite （M-A）, toughness of the weld metal is reduced.