热处理对镍基625合金带极堆焊层组织及耐晶间腐蚀性能的影响  

Effect of post weld heat treatment on microstructure and intergranular corrosion resistance of strip cladding layers of nickel-base alloy 625

作　　者：黄健成[1] 姚润钢[1] 姚上卫[1] 

机构地区：[1]中国船舶重工集团公司第七二五研究所,河南洛阳471023

出　　处：《焊接技术》2016年第7期29-32,4,共4页Welding Technology

摘　　要：采用带极埋弧堆焊方法在低合金耐热钢15CrMoR表面堆焊625合金,研究了焊态及热处理状态下不同成分堆焊层金属的显微组织及耐晶间腐蚀性能。结果表明,热处理后堆焊层析出相的产生是导致晶间腐蚀性能降低的主要原因。焊态下堆焊层金属中的主要析出相为MC型碳化物和Laves相;经热处理后MC,Laves相数量增加,且在晶界产生大量断续分布的M_(23)C_6型碳化物,晶内析出大量弥散分布的γ″相。M_(23)C_6的析出和聚集长大在晶界附近形成严重的贫铬区,使得晶间腐蚀性能明显下降;Laves相的长大和γ″相的大量析出造成了相附近化学成分的不均匀性,导致腐蚀性能进一步降低。Nickel-based alloy 625 was surfaced on heat-resistant steel 15 CrMoR by submerged arc strip cladding method. Effect of post weld heat treatment(PWHT) on microstructure and intergranular corrosion(IGC) resistance of two layers with different chemical composition were studied. Results showed that precipitates observed during heat treatment contributes to the increasing corrosion rate. Only MC carbides and Laves phase were found in as welded metal. MC and Laves phase grew in quantity, while a large number of M23C6 carbides discontinuous distributed on grain boundary and γ'' phase dispersed within grain during heat treatment. The nucleation and growth of M23C6 cause chromium depleted zone around grain boundaries, critically decreasing IGC resistance. The growth of Laves phase and precipitation of γ'' phase resulted in inhomogeneity of chemical composition relative to surrounding matrix, which led to the corrosion resistance further reduced.

关 键 词：带极埋弧堆焊 镍基625合金 组织 晶间腐蚀 

分 类 号：TG445[金属学及工艺—焊接] TG455