Considering Environmental and Mean Stress Effects in Understanding HCF Performance of Mechanically Surface Treated Metallic M

Author:  Zay, Mhaede, Wollmann, Wagner
Source:  Conf Proc 2011: ICSP-11 South Bend, IN USA (pgs. 255-260)
Doc ID:  2011042
Year of Publication:  2011
Abstract:  
Abstract It is often reported that high-cycle fatigue (HCF) cracks in metallic components that are mechanically surface treated by shot peening (SP) or ball-burnished (BB) nucleate subsurface rather than at the surface. This may be caused by residual tensile stresses balancing the outer process-induced residual compressive stress field. Therefore, for understanding fatigue results after SP and BB, the tensile mean stress sensitivity of the particular material should be known. Since subsurface fatigue cracks have to nucleate under quasi-vacuum conditions, the knowledge of the fatigue strength in vacuum is desirable, too. HCF tests in axial loading in vacuum and air were performed on bainitic and austenitic steels as well as on a metastable