Munetoh Hashimoto

An X-Ray Study on the Residual Stress and Fatigue Characteristics of Titanium Carbide Coated Steels

The aim of the present study is to clarify the residual stresses of TiC coated steels through the mesurement by means of X-ray diffraction method and to clear the effect of TiC coating on fatigue strength. Three kinds of specimens are used and TiC are coated by chemical vapor deposition (CVD) by changing the coating condition. The residual stress has been measured by the so-called 28,-sin2ψ method. To investigate the effect of residual stress of TiC coatiiig on the fatigue strength, fatigue tests were conducted using flat plate and cantileuer plate type specimens. As the results, it was found that there exist compressive residual stress in the TiC layer, and fatigue strength of TiC coated steels become lower than ones of the specimens without TiC coating, but treatments of quenching and tempering followed by TiC coating improve the fatigue properties considerably.

An X-Ray Study on the Residual Stress of Shot-Peened Steels

Although shot peening treatment is widely applied to the machine parts for the purpose to produce compressive residual stresses in order to improve mechanical properties, detailed relation between the shot peening condition and the residual stress distribution near the surface layers is not clarified yet. The aim of the present study is to find out the precise effect of shot peening condition on the fatigue life through the control of residulal stress distribution near the surface layers of Ni-Cr-Mo steel plates which are used for various kinds of gears or other machine parts. The residual stress near the surface layers of shot peened specimen followed by grinding was measured by the use of X-ray diffraction method. The residual stress distribution across the thickness direction was also measured removing the surface layers by electrolytical polishing.