Effect of Shielding Gases on Austenitic Stainless Steel Overlay by FCAW Process on Low Alloy Steel
Effect of Shielding Gases on Austenitic Stainless Steel Overlay by FCAW Process on Low Alloy Steel
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保护气体对低合金钢 FCAW 工艺奥氏体不锈钢堆焊层的影响
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
B. Chauhan
中科院分区：
文献类型：
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作者：
J. Girish;B. Chauhan
用于化学、石化和炼油厂的压力容器和高压热交换器通常由抗蠕变低合金钢材料制造。这些设备的内表面使用奥氏体不锈钢进行表面处理（包层），以防止低合金钢受到工艺流体的侵蚀性腐蚀影响。小直径工艺喷嘴和其他部件通常使用药芯焊丝电弧焊工艺进行堆焊;纯CO2用作保护气体。如今，许多客户/工艺许可方正在严格要求限制使用100% CO2作为FCAW工艺的保护气体。这就需要开发采用各种保护气体/混合物的不锈钢FCAW堆焊工艺。采用药芯焊丝电弧焊（FCAW）工艺，在低合金钢（1 1/4 Cr - 1/2 Mo）上存款347型奥氏体不锈钢，堆焊层为309 L型不锈钢阻挡层和347型不锈钢阻挡层。在实验的第一阶段中，采用两种不同的保护气体：纯Ar和纯CO2。对来自各种堆焊试样的样品进行宏观检查以研究焊道特性，并进行微观检查以研究铁素体相分布和夹杂物。还进行了使用光谱法的化学分析，目的是详细了解由于碳含量与保护气体和包芯线焊剂的反应性质而对碳含量的影响。铁素体调查，使用Feritescope和弯曲延性试验也进行了。
Pressure vessels and high pressure heat exchangers used for chemical, petrochemical and refineries are normally fabricated from creep resistant low alloy steel material. The internal surfaces of these equipments are given a surface treatment (cladding) using austenitic stainless steel in order to prevent the low alloy steel from aggressive corrosion effects of the process fluids. Small diameter process nozzles and other components are normally weld overlaid using flux cored arc welding process; pure CO2 is used as a shielding gas. Nowadays, stringent requirements are being enforced by many customers/process licensors on restricting the use of 100% CO2 as shielding gas for FCAW process. This necessitates development of stainless steel FCAW weld overlay procedures employing various shielding gases/mixtures. The current study involves the use of flux cored arc welding (FCAW) process to deposit austenitic stainless steel (Type 347) overlay on low alloy steel (1 1⁄4 Cr – 1⁄2 Mo) .Cladding was performed by depositing a barrier layer of type 309L stainless steel and one layer of type 347 stainless steel over the barrier layer. In the first phase of experiment two different shielding gases were employed: pure Ar, and pure CO2. Samples from various overlay coupons were subjected to macroscopic examination for studying bead characteristics and microscopic examination for studying ferrite phase distribution and inclusions. Chemical analysis using spectroscopic method was also carried out with intent to understand, in detail, the effect on carbon content due to nature of reactions it undergoes with the shielding gas and flux of the cored-wire. Ferrite survey, using Feritescope and bend ductility tests were also carried out.