2000MPa高强度钢的超高周疲劳破坏行为

Failure Behavior of Ultra-high Cycle Fatigue of a 2 000 MPa Grade High Strength Steel

通过USF-2000超声波疲劳试验机研究了500 kg真空感应炉+电渣重熔冶炼的2000 MPa高强度钢(%:0.45C、2.0Si、0.9Cr、0.001S、0.005P、0.026Al、0.001 5O、0.002 8N)在共振频率20 kHz、载荷比R=-1,共振间隙150 ms时的超高周疲劳破坏行为。结果发现,疲劳裂纹大部分起源于钢中非金属夹杂物(夹杂平均尺寸12.3μm),钢的疲劳强度和寿命随夹杂物增大而降低;内部夹杂物引起的疲劳破坏往往呈鱼眼型;随疲劳断口裂纹源夹杂物处应力场强度因子ΔK_(inc)的减小,钢的疲劳寿命N_f增加。

The failure behavior of ultra-high eyele fatigue of a 2000 MPa grade high strength steel （0. 45C, 2. 0Si, 0.9Cr, 0. 001S, 0. 005P, 0. 026A1, 0.001 50, 0.002 8N） melted by 500 kg vacuum induction furnace ＋ electro-slag remelting has been studied by USF-2000 ultrasonic fatigue test machine with resonant frequency 20 kHz, load ratio R = -1, resonantgap 150 ms. Results found that the fatigue eraek originated mostly from non-metallie inelusions（ inclusion average size 12. 3 μm） ; with increasing inclusion size both fatigue strength and fatigue life of steel decreased; fatigue failure area eaused by inner inelusion presented fish-eye shape; and with deereasing the stress intensity faetor range AKinc at fatigue eraek originated site of inelusion, the fatigue life Nf of steel inereased.