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研究了热处理对铸造4Cr9Si2耐热钢的显微组织和性能的影响。结果表明:铸造4Cr9Si2钢在铸态下组织为板条马氏体,经860℃×2 h退火处理后,在铁素体基体上析出粗大粒状和条状M_(23)C_6型碳化物,硬度降低,但冲击吸收功很低;经1020℃×2 h空冷正火+720℃×2 h回火热处理后,随后的冷却速率对显微组织和冲击吸收功影响很大。采用炉冷方式冷却的4Cr9Si2耐热钢存在高温回火脆性现象,组织中有细小弥散碳化物析出,造成二次硬化,硬度较720℃回火后水冷的试样高,冲击吸收功低。
The effect of heat treatment on the microstructure and properties of 4Cr9Si2 heat-resistant steel was investigated. The results show that the as - cast 4Cr9Si2 steel is slab martensite in the as - cast condition. After annealing at 860 ℃ for 2 h, coarse granular and strip M 23 C 6 carbides are precipitated on the ferrite matrix. The hardness But the impact absorption power is very low. After 1020 ℃ × 2 h air-cooled normalizing and 720 ℃ × 2 h tempering heat treatment, the subsequent cooling rate greatly affects the microstructure and impact absorption work. 4Cr9Si2 heat-resistant steel cooled by furnace cooling has tempering brittleness at high temperature. Small and diffuse carbides precipitate in the structure, resulting in secondary hardening. The samples hardened by tempering at 720 ° C have higher water absorption and lower impact absorption.