• Journal of the Korean Society for Heat Treatment
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• v.17 no.6
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• pp.336-341
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• 2004

The effect of shot peening conditions on the fatigue properties of heat-treated spring steel has been investigated by using residual stress measurement and metallography. The mechanical properties of material did not change so much by shot peening. However, the fatigue strength and fatigue life increased about 20% to 40% by 1-step and 2-step shot peening process. The fatigue strength and life were closely related to the value and position of maximum compressive residual stress by shot peening process. In the case of warm shot peening, compressive residual stress of specimens shot peening processed at $200^{\circ}C$ was higher than those of specimens shot peening processed at room temperature, $100^{\circ}C$ and $300^{\circ}C$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.26 no.6
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• pp.1209-1216
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• 2002

The requirements of coil spring fer higher fatigue strength have been increased to achieve the weight reduction of a vehicle. As the possible increase in fatigue strength by using the conventional shot peening treatment is found to be limited, it is necessary to modify the shot peening treatment. The warm shot peening is a shot peening treatment carried out within warm temperature range. The aim of this paper is to analyze some experimental results concerned with the effect of warm shot peening and to discuss the mechanism of warm shot peening in detail. By the results of rotating bending fatigue test, the fatigue strength of test specimen increases up to 23.8% in the production condition of warm shot peening at 200$\^{C}$ compared with conventional shot peening. The major reason why the warm shot peening is effective to the improvement of fatigue strength is the increase of a compressive residual stress distribution, which can be caused by more effective deformation under the condition of warm temperature.

• Journal of the Korean Society of Safety
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• v.26 no.1
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• pp.15-20
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• 2011

This study deals with the effect of the shot peening in SCM420H planetary gears. The hardness and roughness of the gear surface can be improved by shot blast and shot peening. there in, the shot peening techniques are welcomed especially as one of the physical surface improvement methods. The two treatments are used widely, because of the qualitative analysis of shot blast and shot peening has become possible and the surface treatment can be done with little costs compared with other surface improvement methods. Therefore, this study investigates the effects of shot blast and shot peening in surface shape. The fatigue strength test at a constant stress amplitude is performed by using an electrohydraulic serve-controlled pulsating tester. And fatigue test also explained characteristics of shot blast and shot peening of planetary gears.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.10
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• pp.1590-1596
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• 2001

The shot peening process is most often used to improve fatigue properties of metal parts. The single most critical parameter of the shot peening process is the shot ball itself. Without the correct quality media, all other shut peening parameters are extraneous and the desired fatigue improvement and consistency of improvement will not be achieved. Shot peening involves modifications of the surface and subsurface condition of a material that can be described by the change of the residual stresses, the hardness, and the surface roughness. This Paper Presents the shot peening to optimize the shot ball parameters. The effect of shot peening parameter on the surface roughness, surface hardness and residual stress are investigated.

• Journal of the Korean Society for Precision Engineering
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• v.14 no.9
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• pp.61-67
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• 1997

Hardened layer and compressive residual stress created by carburized treatment effect on bending strength of gear massively. Also, shot peening treatment improves the strength of carburized gear as it does the hardness and residual stress of surface layer. In these days shot peening techniques are welcomed as one of physical improvement ways around the surface of materials. It is used widely because qualitative analysis of shot peening has become possible and surface treatment can be done with very little costs comparaed to other surface improvement methods. Therefore this study investigates the effect of shot peening in surface shape and bending fatigue strength after doing many kinds of shot peening treatments, then doing fatigue test and also explained characteristics of shot peening gear.

• Journal of the Korean institute of surface engineering
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• v.37 no.5
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• pp.273-278
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• 2004

The requirements of getting spring steel with higher fatigue strength have been increased to achieve the weight reduction of a vehicle. As the possible increment in fatigue strength by using the conventional shot peening treatment is found to be limited, it is necessary to modify the shot peening treatment. In this study, to investigate the effects of warm shot peening on increasing fatigue strength, tests are conducted on spring steel SAE9524. By the results of rotating bending fatigue tests, the fatigue strength increases up to 23.8% in warm shot peening specimens at $200^{\circ}C$ compared with conventional shot peening. The major reason why the warm shot peening is effective to the improvement of fatigue strength is the increment of the compressive residual stress, which can be effectively formed by shot peening under the condition of warm temperature than room temperature.

• Journal of the Korean institute of surface engineering
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• v.36 no.6
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• pp.475-479
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• 2003

In this study, to investigate the effects of 2-step shot peening at the surface of spring steel, tests are conducted on spring steel and shot peened specimens. Various tests are accomplished to evaluate mechanical properties influenced by shot peening process, and fatigue tests are also performed to evaluate the improvement of fatigue strength. And then the residual stresses are examined. The mechanical properties of material did not change so much by shot peening. However, the fatigue strength of notched specimen remarkably increased. In the case of 1-step shot peening, fatigue strength increased by about 20％ than unpeened specimen. Especially, in the case of 2-step shot peening, fatigue strength increased by about 40％, because the residual compressive stress at surface was higher than that of 1-step shot peened specimen. The fatigue strength and life are closely related to the value and position of maximum compressive residual stress by shot peening.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.959-963
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• 1996

Hardened layer and compressive residual stress created by carburized treatment effect on bending fatigue strength of gear massively. Also, shot peening treatment improves the strength of carburized gear as it does the hardness and residual stress of surface layer. In these days shot peening techniques are welcomed as one of physical improvement ways around the surface of materials. It is used widely because qualitative analysis of shot peening has become possible and surface treatment can be done with very little costs compared to other surface improvement methods. Therefore this study investigates the effect of shot peening in surface shape and bending fatigue strength after doing many kinds of shot peening treatments, then doing fatigue test and also explained characteristics of shot peening gear.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2005.11a
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• pp.228-229
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• 2005

The compressive residual stress, which is induced by shot peening process, has the effect of increasing the intrinsic fatigue strength of surface and therefore would be beneficial in reducing the probability of fatigue damage. However, it was not known that the effect of shot peening in corrosion environment. In this study, the effect of shot peening on corrosion fatigue crack growth of sping steel immersed in 6% $FeCl_3$ solution and corrosion characteristics with considering fracture mechanics. The results of the experimental study corrosion fatigue characteristics of spring steel are as follows; the fatigue crack growth rate of the shot peening material was lower than of the un peening material. And fatigue life shows more improvement in the shot peening material than un peening material. This is because the compressive residual stress of surface operate resistance of corrosion fatigue crack propagation. It is assumed that the shot peening process improve corrosive resistance and mechanical property.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.6
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• pp.731-739
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• 2006

Corrosion and lassitude are very important in the metal construction Currently, the shot peening is used much for removing the defect on the surface, improving the fatigue strength on surface. In this study. the influence of shot peening to the corrosion property were investigated in 3.5% NaCl, 10% HNO3 + 3% HF. 6% FeC13. The immersion test was performed on two kind of specimen(Removed corrosion product. RCP and Continuous immersed specimen: CIS). The immersion periods was 3600hours. Corrosion potential. weight loss, and fatigue crack growth characteristics were investigated. The result, shot peening in corrosion potential showed stable potential. Also, shot peening displayed small Weight loss than un peening. And Fatigue crack resistivity of shot peening in corrosion solution's fatigue crack appeared greatly than un peening.