用位错-溶质复合体模型解释马氏体异种钢焊接接头碳迁移过程  

Dislocation-solute vacancy complex model of the carbon distribution in martensite dissimilar metal weld joint

作　　者：蔡志鹏[1] 何雨晨 李克俭[1] 郑云蔚 潘际銮[1] 

机构地区：[1]清华大学机械工程系,北京100084

出　　处：《清华大学学报（自然科学版）》2015年第3期316-321,共6页Journal of Tsinghua University(Science and Technology)

摘　　要：该文对马氏体耐热钢母材和奥氏体焊缝的异种钢焊接接头中产生的碳迁移现象进行了研究,研究对象为9%Cr马氏体耐热钢和2.25Cr焊丝焊接接头。试样经过710℃、20h热处理后,熔合区两侧出现了较明显的增碳层和脱碳层,通过金相观察到马氏体板条生长方向对增碳层有显著影响,随后对试样进行电解腐蚀处理,通过扫描电镜(SEM)观察到电解腐蚀析出物在晶界析出,析出物沿着马氏体板条生长方向分布。传统的上坡扩散理论并不能解释这一现象。该文引入非平衡偏聚理论,提出用位错-溶质复合体模型解释碳在晶内的扩散行为,同时提出碳迁移通道模型解释马氏体板条取向对碳迁移的影响,并通过电子探针实验测定了不同马氏体组织形态下碳元素的分布,进一步证实了该模型的合理性。The carbon distribution was measured in a metal weld joint with the martensitic parent metal and austenite steel.The welding joint used 9%Cr martensite steel and a 2.25 Cr welding stick.The carbon distribution was measured after 20 hof 710℃ heat treatment with a carbon-rich layer and a decarburized layer in the fusion zone.Precipitation is found in the grain boundary with the precipitation distribution affected by the direction of the martensite lath after electrolytic etching.Traditional carbon uphill diffusion theory cannot explain this phenomenon,so a non-equilibrium grain-boundary segregation theory is used to explain this phenomenon. A dislocation-solute vacancy complex model is used to explain the carbon diffusion inside the grains.The channel of carbon distribution model is used to explain how the martensite lath direction affects the carbon distribution.An electronic probe was used to analyze the carbon content in different kinds of martensite lath to confirm the model.

关 键 词：异种钢焊接 非平衡偏聚 碳迁移通道 马氏体板条取向 

分 类 号：TG401[金属学及工艺—焊接]