摘要
利用光学显微镜观察Mn-Ti体系和Nb-V体系600 MPa冷压桥壳钢显微组织,采用MTS-810低频疲劳试验机,在试验频率为10Hz条件下,应用三点弯曲法,对2种成分体系冷压桥壳钢进行疲劳裂纹扩展速率试验,并绘制2种试验材料的裂纹扩展速率da/dN与应力强度因子幅度ΔK的关系曲线。结果表明,2种成分体系桥壳钢显微组织均为铁素体+少量的珠光体,Nb-V体系铁素体晶粒尺寸为3.3μm,Mn-Ti体系铁素体晶粒尺寸为5.8μm。利用线性拟合法,得到Mn-Ti体系和Nb-V体系的Paris方程系数分别为:m=2.629 8,C=4.13×10^(-12) mm/次和m=2.679 9,C=1.30×10^(-12) mm/次,计算得出裂纹扩展门槛值ΔKth分别为46.50和66.58 MPa·m^(1/2)。
The microstructure of 600 MPa Mn-Ti and Nb-V steels for cold stamping axle housing were investigated by means of optical microscope. On the low-frequency fatigue tester MTS-810 with frequency of 10 Hz, the crack propagation rate of two chemical components of the tested steels was tested by using three-point bending method. The relationship between the propagation rate da/dN and the amplitude of stress intensity factor ＆K was drawn. The results showed that the microstructure all of two tested steels were ferrite and pearlite, the grain size of Nb-V steel and Mn-Ti steel was 3.3 μm and 5.8 μm respectively. The coefficient C and m in Paris equation of Mn-Ti steel and Nb-Vsteel were determined as m = 2. 629 8, C=4.13× 10^- 12 mm/cycle and m= 2. 679 9, C= 1.30 × 10 ^-12 mm/cycle respectively, and the threshold value of crack propagation △K th was 46.50 and 66.58 MPa · m1/2 respectively.
出处
《新技术新工艺》
2017年第3期1-4,共4页
New Technology & New Process
关键词
冷压桥壳钢
疲劳裂纹
应力强度因子幅度
裂纹扩展门槛值
晶粒尺寸
cold stamping axle housing steel, fatigue crack, stress intensity factor amplitude, threshold value of crack propagation, grain size
