焊后回火处理对9Cr13轧辊钢堆焊熔覆层组织及回火脆性的影响

Effect of Postwelding Tempering Treatment on Microstructure and Tempering Brittleness of 9Cr13 Surfacing Welding Cladding Layer

利用Cr-Ni-Mn系药芯焊丝对9Cr13轧辊钢进行堆焊,研究了焊后不同回火温度对熔覆层组织、硬度及韧性的影响规律。结果表明,在50~200℃低温回火范围内,熔覆层主要表现为粗大的片状回火马氏体,硬度较高但韧性较低,冲击断口表现为典型的脆性断裂;300~550℃中温回火范围内,随着回火温度升高,熔覆层中粗大片状回火马氏体逐渐减少,硬度逐渐降低,韧性逐渐改善;当回火温度达到550℃时,堆焊熔覆层中的粗大片状回火马氏体消失,表现为细小的板条状回火马氏体与弥散分布的细小颗粒状混合组织,断口出现大量的断裂韧窝,硬度及韧性较高;当回火温度达到600℃时,堆焊熔覆层主要表现为尺寸较大的颗粒状组织,韧性降低;根据冲击韧度值确定了熔敷层的回火脆性温度区间为150~200℃。

Through surfacing welding on 9Cr13 steel roller using Cr-Ni-Mn series of flux-cored wire, the influence of different postweiding tempering treatment on the cladding layer structure, hardness and toughness was studied. The results show that under low tempering temperatures of 50-200 ~C, cladding layer is mainly characterized by thick flake tempered martensite with improved hardness and reduced toughness. The brittle fracture feature can be found on the fracture surface. With increasing tempering temperature from 300℃ to 550℃, the thick flake tempered martensite of the cladding layer is reduced, while hardness and toughness are improved gradually. When the tempering temperature reaches to 550℃, the thick flake tempered martensite of cladding layer disappear. The structure changes to the small plate strips of tempered martensite and dispersion distribution of fine granular mixture structure with higher hardness and improved toughness. The fracture surface appears a large number of dimples. When the tempering temperature is 600℃, the cladding layer structure changes to large granular with reduced toughness. Though the impact toughness test, the brittleness temperature ranges of Cr-Ni-Mn flux-cored wire is determined in the range of 150-200℃.