J Mater Sci Technol ›› 1993, Vol. 9 ›› Issue (3): 205-209.

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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   

  • Received:1993-05-28 Revised:1993-05-28 Online:1993-05-28 Published:2009-10-10

Abstract: 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 yield strength 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% and 0.1%plastic strain are about 436 MPa and 463 MPa respectively.The 0.05% yield strength will approximately 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.

Key words: biaxial stress, surface yielding, Mises criterion, strain hardening exponent