采用重稀土改善焊缝韧性的研究

AN INVESTIGATION ON IMPROVING THE TOUGHNESS OF WELD METAL BY ADDING RAPE EARTH ELEMENT

摘要:

用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线能谱仪(EDAX)研究了重稀土元素对低合金钢焊缝金属韧性的影响.结果发现,采用适当的焊条药皮配方和焊接工艺可使重稀土元素微量过渡到焊缝金属中(约10ppm),减少了夹杂物的面密度和面积百分数,显著提高了焊缝金属的低温韧性。夹杂物的减少和低温韧性的提高有很好的对应关系,因此可以认为,重稀土元素对焊缝金属的净化和变质作用是提高焊缝低温韧性的主要原因。此外,还对焊缝金属中夹杂物的类型进行了较深入的鉴别。

Abstract:

The influence of heavy rare earth element on the weld metal of low alloy steelhas been investigated by means of scanning electron microscope (SEM),transmittedelectron microscope (TEM) and X-ray energy dispersion spectrometer (EDAX).Theresults showed that heavy rare earth element can be transferred into the weld metalup to an amount of about 10 ppm by adopting appropriate prescription of flux coat-ing and welding procedure.The rare earth element reduces the area density and areapercentage of inclusions and increases appreciably the low temperature toughness of weldmetal.There is a good relationship between the decreasing of amount of inclusion andthe increasing of toughness.So the main reason for the low temperature tonghnessbeing improved can be attributed to the cleaning and modification of the weld metalby adding rare earth.The rare earth element mainly concentrates in the silicate inclu-sions containing Ti and Mn,in which the rare earth content is hundreds times morethan its average in the weld metal.