空气和水下环境304L不锈钢密封堆焊工艺对比  

Comparison of 304L Stainless Steel Sealing Overlay Welding Processes in Air and Underwater Environments

作　　者：赵友亮 朱加雷[1] 赵晓鑫 张仁祥 赵志博 李桂新 赵亮 ZHAO Youliang;ZHU Jialei;ZHAO Xiaoxin;ZHANG Renxiang;ZHAO Zhibo;LI Guixin;ZHAO Liang(School of Mechanical Engineering,Beijing Institute of Petrochemical Technology,Beijing 102617,China)

机构地区：[1]北京石油化工学院机械工程学院,北京102617

出　　处：《中国表面工程》2024年第4期280-290,共11页China Surface Engineering

基　　金：国家自然科学基金联合基金重点支持项目(U22B20127);北京市科技计划重点项目(KZ202210017023);北京市属高校分类发展项目(11000023T000002199202)。

摘　　要：核电站乏燃料池长时间服役后因腐蚀产生裂纹、孔洞等缺陷,影响安全运行,但对水下环境焊接修复的研究较少。采用ER-2209双相不锈钢实心焊丝完成空气环境和水下环境304不锈钢密封堆焊层的制备。结果表明:堆焊层表面成形连续均匀,无裂纹、夹渣、焊瘤和咬边等缺陷。堆焊层内的微观组织包含双相不锈钢组织以及奥氏体不锈钢组织,且两者之间呈区域性分布。堆焊层横向拉伸试件的应力应变曲线抗拉强度高于母材,变形过程中诱发马氏体相变,使得母材的应力应变曲线后段的强度提高,总体伸长率高于堆焊层。在焊道间熔合处,奥氏体晶粒的结晶取向发生偏转,焊道的织构强度增强,两种环境中顶部横向拉伸试件呈现出较高的抗拉强度和较低的伸长率。由于水下环境的快冷作用促使双相不锈钢组织中的δ晶粒向γ的转变受到抑制,存在晶粒度较大的δ晶粒,δ铁素体的层错能较高,堆焊层硬度提高;快冷作用促使奥氏体不锈钢组织中生成大量沿奥氏体晶界分布的板条状铁素体,板条状铁素体区域性分布,提高了奥氏体不锈钢组织的硬度。堆焊层的极化曲线中可以观察到明显的钝化区间,堆焊层具备较好的耐腐蚀性能。分别在空气环境和水下环境制备了304L不锈钢堆焊层,研究了堆焊层的宏观形貌、微观组织和物相组成,分析了堆焊层的力学性能、显微硬度和耐腐蚀性能,研究结果对304L不锈钢浅表裂纹修复工程有重要作用。Nuclear energy has been recognized as one of the best options for meeting the growing demand for electricity.Currently,the cladding of the spent fuel pool of a second-generation nuclear power plant is made of 304L stainless steel.Corrosion cracks,pitting corrosion,and other defects are inevitable because of long-term immersion in a boric acid environment.As the defects further expand,they penetrate the entire stainless-steel wall panel,which may lead to leakage of the spent fuel pool and pose major safety concerns.Spent fuel is radioactive;therefore,construction personnel cannot work in such an environment.Therefore,welding repair in an underwater environment is particularly important.However,relatively little research has been conducted worldwide on welding repair in underwater environments.In this study,an ER-2209 duplex stainless-steel solid welding wire was used to prepare a sealed surface layer on 304 L stainless steel in both air and underwater environments.The results showed that the weld bead formations on the surface of the surfacing layer were continuous and uniform,without defects such as cracks,slag inclusions,weld beadings,or undercuts.The microstructure inside the surfacing layer includes both duplex and austenitic stainless steels,with a regional distribution between the two.The proportion ofδgrains in the microstructure of duplex stainless steel in the rapid cooling mode was high,the grain size was large,and a large amount of SF precipitated from austenitic stainless steel.The tensile strength obtained from the stress–strain curve of the transverse tensile specimen of the overlay layer was higher than that of the BM.A martensitic transformation was induced during the deformation process,which increased the strength of the fracture after the stress–strain curve of the BM,and the overall elongation was greater than that of the overlay layer.The crystalline orientation of the austenite grains was deflected at the fusion point between the weld beads and the texture strength of the weld bead was e

关 键 词：熔深 微观组织 拉伸强度 织构强度 耐腐蚀性 

分 类 号：TG456[金属学及工艺—焊接]