喷丸强化后30CrMnSiNi2A钢表面完整性对其抗疲劳性能的影响*

采用气动式喷丸机对铣削加工和磨削加工的30CrMnSiNi2A钢疲劳试样进行喷丸强化处理,利用扫描电镜、表面粗糙度仪和X射线应力测试仪分别对试样的表面形貌、粗糙度和残余应力进行测试,并对不同表面状态的试样进行疲劳试验,分析表面完整性对其疲劳寿命的影响。结果表明:该钢铣削加工时易在表面留下撕裂、鳞刺和折皱等加工缺陷,导致严重的应力集中,试样疲劳寿命较低;喷丸强化处理能有效降低铣削加工试样的表面粗糙度,增加残余压应力水平,从而提高了其疲劳寿命。磨削试样喷丸处理后试样表面残余应力增大,但表面质量大幅下降,疲劳寿命略有降低。

Influence of Surface Integrity on Fatigue Resistance of the 30CrMnSiNi2A Steel After Shot Peening

The 30CrMnSiNi2A steel fatigue specimens produced by milling and grinding methods were treated with pneumatic shot peening equipment. The surface topography, roughness and residual stress were measured using the scanning electronic microscope (SEM), surface profile tester, and Xray stress tester. The fatigue tests were carried out for the specimens with different surface states. Subsequently, the influence of surface integrity on the specimens fatigue life was analyzed. The results show that the surfaces of the steel specimens produced by milling are apt to engender processing defects such as tearing, scales, and crumpled folder, which lead to serious stress concentration and reduce the fatigue life of the specimens. The shot peening treatment reduces the surface roughness and improves the residual compressive stress. Therefore, the fatigue lives of specimens produced by milling are improved after shot peening. The residual compressive stress of specimens produced by grinding is also improved, however, the fatigue life was falls slightly because of their serious destroyed surface qualities after shot peening.