Surface Yielding of Metals by X-ray Diffraction

Xiuying GAI Jiabao LI Zengqiao KANG State Key Lab.for Fatigue and Fracture of Materials,Institute of Metal Research,Academia Sinica,Shenyang,110015,ChinaJiawen HE Xi’an Jiaotong University,Xi’an,710049,China

摘 要：<正> Surface yielding of metallic material was measured with strain gage and X-ray diffraction methods.The results show that.when the residual stress in the transverse direction is involved,the surface yieldstrength should be evaluated with biaxial Mises criterion.For a medium carbon high strength steel,the yield strength of the bulk material is 581 MPa and the surface yield strengths for 0.05% and0.1%plastic strain are about 436 MPa and 463 MPa respectively.The 0.05% yield strength willapproximately increase to 788 MPa after shot peening.In the early stage of plastic deformation,strain hardening in the surface layer is quite different from that of the bulk sample.

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