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本文采用W极氩弧焊熔融来模拟焊缝,研究在C-Mn-Si系焊缝金属中,影响针状铁素体形核的因素。结果表明,在CaF_2保护下的C-Mn-Si系合金的焊缝金属中,当Si、Mn匹配在一定范围内,能使焊缝组织出现高比例的针状铁素体。并通过碳膜复型、电子显微镜、能谱分析和x光衍射分析发现,针状铁素体是在大的奥氏体晶粒内部的非金属夹杂物上非自发形核。并且还发现,较高密度微小的夹杂物(一般在1μm以下)弥散分布对针状铁素体形核更为有利。如果在C-Mn-Si系焊缝中加入少量的Ti,那么不但能细化晶粒,而且能增加TiN、TiO这些细小难溶的非金属夹杂物颗粒浓度,大大提高形成针状铁素体的机率。
In this paper, W-TIG fusion was used to simulate the weld and the factors affecting the nucleation of acicular ferrite in C-Mn-Si-based weld metal were studied. The results show that in the weld metal of C-Mn-Si alloy under the protection of CaF_2, when the Si and Mn are matched within a certain range, a high proportion of acicular ferrite can be formed in the weld microstructure. The results show that acicular ferrite is non-spontaneous nucleation on the non-metallic inclusions inside the large austenite grains by carbon double coating, electron microscopy, energy dispersive spectroscopy and x-ray diffraction analysis. It has also been found that the dispersive distribution of microstructural inclusions (generally below 1 μm) with higher density is more favorable for acicular ferrite nucleation. If a small amount of Ti is added into the C-Mn-Si weld, not only the grain can be refined, but also the concentration of finely-divided non-metallic inclusions such as TiN and TiO can be greatly increased to form acicular ferrite Chances.