GH4169高溫合金車削表面完整性對(duì)疲勞性能的影響

GH4169高溫合金車削表面完整性對(duì)疲勞性能的影響Effect of Surface Integrity of Turned GH4169 Superalloy on Fatigue Performance

通過車削和旋轉(zhuǎn)彎曲疲勞實(shí)驗(yàn)，研究直接時(shí)效態(tài)GH4169高溫合金車削進(jìn)給量對(duì)表面完整性的影響，以及表面完整性對(duì)疲勞壽命的影響。結(jié)果表明：當(dāng)進(jìn)給量f從0.2 mm/r減小到0.02 mm/r時(shí)，表面粗糙度Ra從1.497 μm減小到0.431 μm；表面殘余應(yīng)力從拉應(yīng)力狀態(tài)逐漸轉(zhuǎn)變?yōu)閴簯?yīng)力狀態(tài)；表面塑性變形層從8 μm減小到2 μm左右；表面應(yīng)力集中系數(shù)是GH4169疲勞壽命的主要影響因素，隨著表面應(yīng)力集中系數(shù)增大，疲勞壽命顯著下降；在實(shí)驗(yàn)參數(shù)范圍內(nèi)，當(dāng)f＝0.13 mm/r時(shí)，可獲得好的表面完整性，表面應(yīng)力集中系數(shù)Kst為1.166，表面顯微硬度為405.27HV0.025，表面殘余應(yīng)力為82.08 MPa，獲得的平均疲勞壽命為6.98×104周次；車削表面疲勞斷口具有多源疲勞斷裂特征，疲勞源起始于試件加工表面的缺陷處。

Through turning and rotary bending fatigue test, the effect of turning feed on GH4169 superalloy surface integrity, and the effect of surface integrity on fatigue life were studied. The results show that the surface roughness Ra decreases from 1.497 μm to 0.431 μm when the turning feed decreases from 0.2 mm/r to 0.02 mm/r. The surface residual stresses are changed from tensile stress to compressive stress. The depth of plastic deformation layer decreases from 8 μm to 2 μm. The surface stress concentration factor has the most significant effect on the fatigue life of GH4169. With the increase of stress concentration factor, the fatigue life decreases significantly. When f is 0.13 mm/r, the surface stress concentration factor Kst is 1.166; the surface micro-hardness is 405.27HV0.025; the surface residual stress is 82.08MPa; and the average fatigue life is 6.98×104 cycles. The multiple cracks are initiated at the machined surface defects of GH4169 superalloy specimen.

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