异质焊头Cr5Mo/Cr21Ni12碳扩散的研究

STUDY ON CARBON DIFFUSION IN Cr5Mo/Cr21Ni12 DIS- SIMILAR AETAL WELDS

利用透射电子显微镜（ＴＥＭ）、能谱仪（ＥＤＸ）和电子探针显微分析仪（ＥＰＭＡ）研究了珠光体钢／奥氏体钢（Ｃｒ５Ｍｏ／Ｃｒ２１Ｎｉ１２）异质焊头在高温时效和长期服役中元素Ｃ，Ｃｒ，Ｎｉ，Ｆｅ的扩散行为结果表明：时效时奥氏体钢中Ｃｒ，Ｎｉ原子向熔合界面方向扩散，Ｆｅ原子向相反的方向扩散；增碳层中析出碳化物Ｍ２３Ｃ６的成分与时效时间无关；增碳层最高含碳量由析出碳化物的类型、成分及紧靠熔合界面奥氏体钢中的Ｃｒ含量决定．并建立了碳的扩散模型．

The diffusion behavior of carbon, Cr, Ni and Fe in dissimilar metal welds between a ferritic steel and an austenitic steel (Cr5Mo/Cr21Ni12) has been investigated by using transmission electron microscopy (TEM), energy dispersive X-ray microanalysis (EDX) and electron probe microanalyzer (EPMA). The results show that Cr and Ni diffuse toward the weld interface while Fe diffuses in the reverse direction; the composition of carbide M23C6 precipitated in carbon-enriched zone is independent of aging time at 500℃; the maximum carbon concentration of carbon-enriched zone is determined by the type and composition of carbides and the concentration of Cr adjacent to the weld interface. A diffusion model was given to describe the carbon diffusion.