奥－贝球铁焊缝的组织与力学性能

Microstructure and Mechanical Properties of Austempered Ductile Iron Welds

用Ｘ射线衍射仪、光学显微镜和电子显微镜，系统地研究了球铁焊缝金属等温贝氏体转变过程，等温温度及等温时间对焊缝组织与力学性能的影响。研究结果表明，球铁焊缝金属贝氏体相变快，等温时间在１５～２４０ｍｉｎ范围内焊缝基体组织主要为贝氏体铁素体和残余奥氏体且具有高的综合力学性能。随着等温温度从３１０℃增至４００℃，焊缝金属中残余奥氏体量增多，贝氏体铁素体条宽化，焊缝塑性提高，强度降低。

The isothermal bainitic transformation in ductile iron welds and the effects of austempering temperature and time to the microstructure and mechanical properties of the weldswere systematically studied by means of X-ray diffraction, optical and electron microscopy.The experimental results show that the rate of bainitic transformation in ductil iron welds is fastand the weld structure mainly consisted of bainitic ferrite and retained austenite has high levelmechanical properties in the range of 15～240min during austempering time. With increasingaustempering temperature from 310℃ to 400℃, the amount of retained austenite increases andbainitic ferrite become wider. As the result, the plasticity of welds increases, but the strength of welds decreases.