摘要
研究了新型高CoNi超高强度合金钢的组织和性能.在最佳热处理条件下,达到最佳强韧性,σb ≥1960MPa,σ0.2≥1740MPa,断裂韧性K1c≥112 MPa·m1/2,其组织为典型的淬火回火板条马氏体,等温回火处理产生二次硬化反应,析出与基体共格的细小弥散合金碳化物M2C沉淀使其得到强化.析出相与基体间的共格关系随回火温度的升高而失去,并转化为M23C6或 M7C3.分布在晶界的膜状奥氏体有韧化作用.在较高温度下回火,M2C粗化、失主与基体间的共格关系,并向其它碳化物转化,以及在晶内形成大量奥氏体,使性能下降.
The effect of heating on the microstructure and mechanical properties of new-type high Co-Ni alloy is investigated. The optimal strength and toughness is attained when tempered at 482 ℃ for 5 h, σb ≥1960 MPa, σ0.2 ≥1740 MPa, and K1c ≥112 MPa·m1/2. Microstructure examinations show that the steel is the typical tempering martensitic steel, the superior performance is achieved by precipitating fine carbides during isothermal tempered and the needle-shaped carbides precipitated in the coherent way with ferrite matrix, and the reverted austenite had a thin-film morphology presenting in plate boundary. When tempered at much higher temperature, needle-shaped carbides of M2C would coarsen and loss the coherent relationship with matrix, and changed into other kinds stable carbides, such as M23C6 and M7C3; meanwhile, the volume fraction of revered austenite increased rapidly in-lath and inter-lath, which cause the properties descended dramatically.
出处
《材料研究学报》
EI
CAS
CSCD
北大核心
2002年第3期331-336,共6页
Chinese Journal of Materials Research
基金
国家九五重点攻关课题97060900.
