摘要
本文研究了热处理对GCr15轴承钢断裂韧性K_(Ic)和疲劳裂纹扩展速率da/dN的影响。试验结果表明:基体成分及组织是影响K_(Ic)和da/dN的主要因素;淬火加热温度升高,K_(Ic)降低,da/dN增快;提高回火温度,K_(Ic)增加,da/dN减慢,但在230℃回火时,因处于回火马氏体脆性区,K_(Ic)急烈下降,da/dN增加;在低温回火范围内,淬火加热温度对K_(Ic)和da/dN的影响远比回火温度对这两种力学性能指标的影响强烈。对GCr15钢疲劳断口和疲劳裂纹扩展过程观察后认为:在门槛区附近,疲劳裂纹的扩展以沿晶为主;中速区则以断续的再生核机制进行扩展;快速区至最后断裂阶段表现为准解理和沿晶断。
This paper deals with the influence of heat treatment on the fracture toug-
hness K_Ic and fatigue crack growth rates da/dN in GCr15 steel. The results
show that the composition and microstructure of the matrix in GCr15 steel are
major factors in the influence on the fracture toughness and fatigue crack growth
rates. The fracture toughness decreases and fatigue crack growth rates
increase with raising austenitizing temperatures for hardening. The fracture tou-
ghness increases and fatigue crack growth rates decrease with raising tempering
temperatures. But K_Ic decreases and da/dN increase rapidly at 230℃ because of
the effect of tempered martensite embrittlement (TME).
Observations of crack growth process and SEM analyses of fatigue crack
surfaces in GCr15 steel suggest that the intergranular fracture in the near
threshold region prevails. The interrupted renucleation of the fatigue crack in
intermediate crack growth rate region, and the quasi-cleavage with
intergranular fracture in fast crack growth region were observed.
出处
《西安交通大学学报》
EI
CAS
CSCD
北大核心
1991年第2期135-141,共7页
Journal of Xi'an Jiaotong University
