论文部分内容阅读
采用20 kHz超声波疲劳振动试验机对高强度大螺栓钢进行疲劳测试,观察其试样的疲劳断口形貌,分析其疲劳失效机理。结果表明,经过纯净化处理后的高强钢在109周次下的疲劳强度达到700 MPa,比未经纯净化的大螺栓钢提高了100 MPa。通过扫描电镜对疲劳试样断口进行观察,发现大螺栓钢的疲劳起裂分3类:表面起裂、内部夹杂物起裂和内部缺陷起裂,而经过纯净化处理之后的高强钢,起裂形式为表面起裂和内部非夹杂起裂。为提高高强钢的抗疲劳性能应从控制夹杂物和改善内部组织两方面着手。
A 20 kHz ultrasonic vibration tester was used to test the fatigue strength of the high strength large bolt steel. The fatigue fracture appearance of the sample was observed and the fatigue failure mechanism was analyzed. The results show that the fatigue strength of high strength steel after pure treatment reaches 700 MPa at 109 cycles, which is 100 MPa higher than that of the unpurified large bolt steel. Through the scanning electron microscopy of the fatigue specimen fracture was observed and found that the large bolt steel fatigue cracking divided into three categories: the surface cracking, internal inclusions and internal defects from cracking, and after purification of high-strength steel after cracking The form of surface cracking and internal non-inclusion cracking. To improve the high-strength steel anti-fatigue properties should be controlled inclusions and internal organization to improve both.