20Cr结构钢疲劳小裂纹扩展行为的研究

Small Fatigue Crack Growth in Structure Steel 20Cr

对正火20Cr的疲劳小裂纹扩展行为进行了研究。使用应力强度因子范围ΔK对小裂纹和长裂纹的扩展速率进行关联。结果表明,在应力比R=0的恒幅载荷下,小裂纹效应不明显;在R=-1的恒幅载荷下,小裂纹效应则较为突出,且穿透裂纹均由多条小裂纹汇合而成。随着裂纹长度的增加,小裂纹的扩展速率出现一个由快变慢又加速的过程。

Small fatigue crack growth was tested in 20Cr,with the small and long fatigue crack growth rates,da/dN,presented against the stress intensity range ΔK.The results show that steel 20Cr does not exhibit a significant small crack effect when stress ratio R=0,but an obvious small crack effect emerges when R=-1 and a cross crack may be composed of numerous small cracks.As the crack lengthens,the growth rate of small cracks appears to repeat a process of acceleration and deceleration.