电站设备转子轴颈等离子弧增材修复的组织与性能

Microstructure and properties of plasma arc additive repairing depositions for the worn rotor journal of power station equipment

针对电站设备转子轴颈的现场修复要求,采用微束等离子熔覆技术,在20Cr2NiMo材料表面实现了不预热单层多道增材熔覆316L合金,分析了熔覆层与热影响区的组织、硬度、化学成分和力学性能.结果表明,熔覆层与基材完全冶金结合,熔覆层与热影响区无裂纹等缺陷;316L熔覆层组织为奥氏体+δ铁素体,一次热影响区可分为脱碳区、粗晶区、细晶区、混晶区,且粗晶区因二次热循环而粗化、细化与软化.316L熔覆层硬度与基材相差小,一次粗晶区硬度最高,但二次粗晶区硬度在476 HV0.3以下,热影响区宽度约为2.5 mm;热影响区抗剪强度高于基材,但基材塑性更好.

In view of the in situ repairing requirements of rotor journal of power plant equipment,a non preheating single-layer and multi-passes additive depositing 316L alloy was achieved on 20Cr2NiMo steel by Micro Plasma Arc Depositing process.The microstructure,hardness,chemical composition and mechanical properties of deposition and heat affected zone were analyzed.The results show that the deposition is metallurgical bonded with the substrate,and there is no crack in the cladding layer and heat affected zone;the microstructure of 316L deposition consists of austenite+δferrite,and the primary heat affected zone can be divided into decarburization zone,coarse-grained zone,fine-grained zone and mixed crystalline zone,and the primary coarse-grained zone is coarsened,refined and softened due to the secondary heat cycle.The difference of hardness between 316L deposition and substrate is small,while the hardness of primary coarse-grained zone is the highest,but that of secondary coarse-grained zone below 476 HV0.3,and the width of heat affected zone is about 2.5 mm;the shear strength of heat affected zone is higher than that of substrate,but the plasticity of substrate is better.