适量的稀土元素可改善焊缝金属组织的形态、细化晶粒、提高韧性。
It was also found out that proper re element addition could increase the toughness of the weld metal and improve its microstructure by grain refinement.
利用焊缝金属组织转变的方法可以在焊接过程中直接降低焊接残余拉伸应力，甚至产生残余压缩应力，有效地提高焊接结构的使用寿命。
Utilizing the transformation of bead metal can reduce tensile stress directly in the course of welding, even produces compressive stress, to improve the service life of welding structure effectively.
结果表明，锆的加入增加了焊缝金属中针状铁素体的含量，改善了焊缝金属的微观组织。
The results show that the addition of Zr increases the content of acicular ferrite and improves the microstructure of weld metal.
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