粉末锻造Fe-2Cu-0.5C-0.11S材料的超声疲劳

Ultrasonic fatigue of powder-forged Fe-2Cu-0.5C-0.11S materials

采用粉末锻造工艺制备Fe-2Cu-0.5C-0.11S材料,对该材料进行超声疲劳试验,研究材料的超声疲劳行为,并对疲劳断口形貌进行观察与分析。结果表明,Fe-2Cu-0.5C-0.11S材料不存在无限疲劳寿命,只存在条件疲劳强度,在10~5,10~6,10~7,10~8周次下材料的疲劳强度分别为543.6,437.7,351.1和281.7 MPa,疲劳断口由裂纹源区、裂纹稳定扩展区和瞬断区组成。裂纹源区内存在扇形分布的疲劳台阶和短小撕裂棱,在疲劳应力较大时主裂纹源位于材料表面,应力较小时主裂纹源位于材料内部;裂纹稳定扩展区内存在大量方向不规则的疲劳辉纹,疲劳辉纹的间隔随疲劳应力减小而减小;瞬断区整体较粗糙且不平整,内部存在大量韧窝。

Fe-2Cu-0.5C-0.11S materials were prepared by powder forging technology.The fatigue behavior and fatigue fracture morphology under different cycles were studied by ultrasonic fatigue test and SEM.The results show that the Fe-2Cu-0.5C-0.11S materials have no infinite fatigue life,but only have conditional fatigue strength.The fatigue strengthes under105,106,107,108cycles are543.6,437.7,351.1and281.7MPa,respectively.Fatigue fracture surface shows crack source region,crack propagation region and final fracture region.Fan shape distribution of fatigue steps and short tearing edges can be found in the crack source region.Main crack source locates on the surface of the material when the fatigue stress is large,but locates inside the material when the stress is small.There are a large number of irregular fatigue striations in the crack propagation region and the fatigue striation interval decreases with the decrease of fatigue stress.The transient fracture region is rough,uneven and with lots of dimples.