Effect of Pre-stress on Stress Shot Peening

Okada, Hideki; Tange, Akira; Tango, Koichi; Ando, Kotoji

doi:10.1299/kikaia.70.647

Cited by 3 publications

(1 citation statement)

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“…Improvement of fatigue limit residual stress was approximately 550 and 810 MPa, respectively. The compressive residual stresses were remarkably increased by SSP (Müller, 1993;Okada et al, 2004).…”

Section: Axial Directionmentioning

confidence: 99%

Improvement of fatigue limit by shot peening for high‐strength steel containing a crack‐like surface defect

Takahashi

Amano

Ando

et al. 2011

International Journal of Structural Integrity

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Purpose -The paper's aim is to investigate the effects of shot peening (SP) on the bending fatigue limit of high-strength steel containing an artificial semi-circular slit. Design/methodology/approach -SP and stress SP (SSP) were conducted on the specimens containing an artificial semi-circular slit with a depth of a ¼ 0.1, 0.2 and 0.3 mm. Then, bending fatigue tests were conducted on the specimens. Findings -The fatigue limit was improved by SP and SSP. In the case of SP and SSP specimens, the specimens with a semi-circular slit under a ¼ 0.2 mm fractured outside the slit, and they had considerably high fatigue limits. Therefore, a semi-circular slit with a depth of under a ¼ 0.2 mm could be rendered harmless by SP or SSP. It was found that the fatigue limit of specimens with a semi-circular slit that received SP or SSP was determined by the threshold condition for non-propagation of fatigue cracks that emanated from outside the slit. Whether the semi-circular slit is rendered harmless or not is decided by the relationship between the stress intensity factor range of semi-circular cracks and the threshold stress intensity factor range. Practical implications -The proposed method can be applied to mechanical parts used in vehicles, aircraft and trains. Originality/value -There are very few examples of evaluations of fatigue limits after SP in materials containing crack-like surface defects. This study calcifies the effect of SP on the fatigue limit having crack-like surface defects.

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Section: Axial Directionmentioning

confidence: 99%

Improvement of fatigue limit by shot peening for high‐strength steel containing a crack‐like surface defect

Takahashi

Amano

Ando

et al. 2011

International Journal of Structural Integrity

Self Cite

View full text Add to dashboard Cite

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Improvement of fatigue strength by shot peening for spring steel specimens containing an artificial surface defect

Takahashi

Amano

Miyamoto

et al. 2007

Transactions of JSSE

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Effects of shot peening on the bending fatigue strength of spring steel specimens (SUP9A) containing an artificial small hole were investigated. Shot peening (SP) and stress shot peening (SSP) were carried out with the specimens containing an artificial drilled hole 0.2, 0.4 and 0.8 mm diameter. Then, bending fatigue tests were carried out with the specimens. The fatigue strengths of specimens containing an artificial small hole were increased by shot peening. Stress shot peening (SSP) was effective in improving fatigue strength. The specimens containing an artificial hole 0.2 mm diameter which received shot peening fractured elsewhere the hole, and they had considerably high fatigue strengths almost equal to those of the shot peened smooth specimens. It was found that the fatigue limit of specimens having an artificial hole of under 0.2mm diameter determined by the threshold condition for non-propagation of fatigue cracks emanated outside the drilled hole. From these results, it can be concluded that an artificial drilled hole under 0.2 mm diameter could be made acceptable by shot peening.

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The Research Committee Report of the Acceptable Defect Size for Spring Steel

Committee¹

2008

Transactions of JSSR

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It is known that the acceptable defect size of steel is smaller for materials having a higher strength. If the acceptable defect size can be increased by shot peening, the reliability of spring could be raised, and it can be anticipated the decrease of production cost of the spring. Then, at this research committee the effects of shot peening on the fatigue strength of spring steel specimens (SUP9A) containing an artificial small hole were investigated. Shot peening (SP) or stress shot peening (SSP) were carried out with the specimens containing an artificial drilled hole 0.2-0.8 mm diameter or a semi-circular slit with 0.3 and 0.6 mm surface length. Then, bending or torsional fatigue tests were carried out with these specimens. SP and SSP improve substantially the fatigue strengths of specimens containing an artificial small hole. Furthermore, the sizes of surface defects, which can be acceptable, by SP or SSP were discussed from the viewpoint of fatigue limit. In order to assess the fatigue limit of spring steel, which possesses surface defects, the fatigue limit assessment diagram (FLAD) was proposed based on the Dugdale model, and the cyclic crack tip opening displacement criterion. The validity of the FLAD was discussed comparing with the past literature data.

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Effect of Pre-stress on Stress Shot Peening

Cited by 3 publications

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Improvement of fatigue limit by shot peening for high‐strength steel containing a crack‐like surface defect

Improvement of fatigue limit by shot peening for high‐strength steel containing a crack‐like surface defect

Improvement of fatigue strength by shot peening for spring steel specimens containing an artificial surface defect

The Research Committee Report of the Acceptable Defect Size for Spring Steel

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