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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。
In this paper, the phenomenon of carbon migration in dissimilar steel welded joints of martensitic heat-resistant steel base metal and austenitic weld was studied. The object of study was 9% Cr martensitic heat-resistant steel and 2.25Cr welding wire . The samples after 710 ℃, 20h heat treatment, the fusion zone appeared on both sides of the obvious carbon layer and decarburization layer, observed by metallographic martensite growth direction of the carbon layer has a significant impact, and then on the test Electrolytic corrosion treatment was carried out. Electrolytic corrosion deposits were observed at the grain boundary by scanning electron microscopy (SEM), and precipitates were distributed along the growth direction of martensite laths. The traditional uphill diffusion theory does not explain this phenomenon. In this paper, we introduce the theory of unbalanced segregation, and propose that the dislocation-solute complex model is used to explain the diffusion behavior of carbon in the crystal. At the same time, the carbon migration channel model is proposed to explain the effect of martensite lath orientation on carbon migration. The pin experiment determined the distribution of carbon elements in different martensite morphologies, further confirming the rationality of the model.