Dual Shot Peening to Maximize Beneficial Residual Stresses in Carburized Steels

Author:  Ahmad, Eaton Corp., Crouch, Metal Improvement Co
Source:  The Shot Peener magazine, Vol 16 / Issue 2, Summer 2002
Doc ID:  2002097
Year of Publication:  2002
Abstract:  
Reprinted with permission from Carburizing: Processing and Performance (1989) ASM International, Materials Park, OH 44073-0002, pages 277-281. ABSTRACT Recent advances in shot peening technology have resulted in the development of a two stage process to maximize the beneficial surface residual stresses induced in hardened, carburized steel, such as SAE 8620, a material commonly used for gears. Steel samples with an effective case depth of 0.72mm (0.029in) were used. Shot peening conditions investigated included: a) single shot peening with: regular hardness steel shot (HRC 45-55), hard steel shot (HRC 55-62), and b) dual peening, first with hard steel shot followed by either smaller diameter hard steel shot at a lower intensity, or smaller diameter glass beads at lower intensities. To investigate the near surface effects initially observed, two samples were dual peened after surface layer removal (0.13mm - 0.29mm).