超低碳贝氏体钢埋弧焊焊接接头韧化机理分析

对超低碳贝氏体钢埋弧焊焊接接头焊缝区显微组织进行分析，发现焊缝区韧性与针状铁素体的含量存在一定的关系。对焊接接头组织进行扫描电子显微镜观察和能谱分析。结果表明，焊缝区针状铁素体以Al₂O₃夹杂物为核心多维形核呈放射状生长；利用EBSD对焊接接头组织进行晶体学取向研究，结果发现，焊缝针状铁素体晶粒取向并不完全随机分布，在某些晶体学方向上存在取向择优；各针状铁素体之间呈大角度晶界；从同一夹杂物上长出的针状铁素体，沿同一方向背向生长的针状铁素体具有相同的取向，可能因为它与奥氏体具有一定的晶体学取向关系。

Toughness mechanism analysis of submerged arc welding joints of ultra-low carbon bainitic steel

In this paper, the microstructure of ultra-low carbon bainitic steel submerged arc welding joints was analyzed, which shows that there is a certain relationship between toughness and the content of acicular ferrite in weld seam. SEM-EDS(Scanning Electron Microscopy-Electron Dispersed Spectrum)observations and analysis of weld seam was conducted on a field emission scanning electron microscope.Results show that several ferrite laths or plates are nucleated on Al₂O₃ inclusion. EBSD analysis was conducted with a FE-SEM to investigate the crystallographic orientation of weld joint microstructures.Results indicate that the crystallographic orientation of acicular ferrite is not completely random. A certain crystallographic orientation is dominant for acicular ferrite. Acicular ferrite is separated by high angle boundaries. Some acicular ferrite laths or plates which are formed on one inclusion and grow in opposite directions have the same crystallographic orientation, presumably because it has some crystallographic orientation relations with the prior austenite.