铁素体-奥氏体异种钢接头的界面组织及力学性能

Interface Structure and Mechanical Property of F/A Dissimilar Metal Welded Joints

关键词:  异种钢接头  蠕变  碳迁移  热应力

Key words:  dissimilar metal welded joint  creep rupture  carbon migration  thermal stress

摘要:

为提高电站锅炉过热器铁素体-奥氏体异种钢焊接接头的高温蠕变断裂强度和服役寿命,设计了专用的镍基填充材料及组合焊接接头。通过对不同焊缝接头的高温蠕变力学试验、焊缝界面组织变化分析、碳扩散和热应力的测试分析,认为在高温低应力的条件下,接头焊缝界面及热影响区碳元素扩散迁移和碳化物聚集是影响接头蠕变断裂强度的重要原因;用镍基焊缝作为过渡段的组合接头具有较小的界面热应力和较高的持久强度。

Abstract:

A special nickel-based weld transition joint has been designed for raising the creep strength and service life of the ferritic-austenitic dissimilar metal welded joints, which have been used in super-heaters of power plant boilers. The interface carbon diffusion, mechanical properties of joints and thermal stress on the interface area have been investigated by means of creep rupture tests, EDAX analysis, FE calculation. It is concluded that in the condition of elevant temperature and low stress, carbon migration and carbide precipitate in the fusion line and HAZ are important facters for effecting creep rupture and the nickel-based weld metal transiting joint can contribute to lower thermal stress and higher creep strength.