镍基材料焊接中高温失塑裂纹DDC的生成机理及研究进展

Formation mechanism and research progress of ductility dip cracking in welding of nickel-based materials

综述了镍基高温合金焊接中高温失塑裂纹(DDC)的生成及最新研究进展,讨论了镍基高温合金焊接过程中评价DDC的几种主要试验方法并着重对最适合于DDC敏感性研究的STF试验进行了详细的叙述,同时综述了高温失塑裂纹的生成机理,影响高温失塑裂纹的因素以及降低DDC敏感性的一些措施。通过综述结果表明降低DDC敏感性的主要措施是采用合适的合金体系和配合合适的焊接工艺。通过合适的合金体系来控制晶界形貌,即一些特定的元素和C形成MC类碳化物并以析出物的形式均匀分布在晶界区域内,它们会有效钉扎晶界使晶界变得更加曲折,阻碍晶界的滑移以及晶粒的长大。使用使合金组织晶粒细化的焊接工艺以及相应后续处理使合金拥有很好的抗高温失塑裂纹的性能。

The formation and the recent research progress of ductility dip cracking( DDC) produced during welding processes of nickel-based superalloy were summarized,several testing DDC methods and its mechanism of DDC during welding processes were discussed. The STF testing method is most suitable for the study of DDC sensitivity and was described in detail. The mechanism of the formation of ductility dip cracking,the factors affecting DDC and the ways to reduce the sensitivity of DDC were also discussed. The main ways to reduce the sensitivity of DDC are to adopt the appropriate alloying system and the appropriate welding process. The appropriate alloying system can control the grain boundary morphology,that is to say,some specific elements and C form MC carbide and are evenly distributed in the grain boundary in the form of precipitates,which will effectively pinch grain boundaries to make the grain boundaries become more tortuous,hinder the grain boundary slip and grain growth. The optimized welding technologies and heat-teartment after welding which make the grains finer can have higher resistance to DDC.