Application of High Corrosion Fatigue Strength Spring Material to Cold-Formed Coil Spring

Yoshikawa, Hidetoshi; Sakakibara, Takayuki; Wakita, Masami

doi:10.5346/trbane.2003.7

Cited by 3 publications

(1 citation statement)

References 7 publications

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“…Coil springs are manufactured by either of two ways: Hot coil, in which the spring is wound at or below the recrystallization temperature, 920 °C. Strength and fatigue resistance is controlled afterwards by an appropriate heat treatment; Cold coil [5], in which the coil winding takes place at room temperature. Residual stresses associated with cold working are essentially eliminated by a relatively low temperature tempering, hardening and conditioning treatments.…”

Section: Introductionmentioning

confidence: 99%

Residual Stresses Associated with the Production of Coiled Automotive Springs

Venter

Luzin

Hattingh

2014

MSF

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Cold coiling of high tensile steel rod into helical coil springs for the automotive industry is a new technique being implemented amongst spring manufacturers worldwide. To characterise this coil production process, the neutron strain scanning technique has been employed to non-destructively elucidate the influence production stages have on the tri-axial residual stress state. Samples investigated represented key production steps in the cold-coil forming process: Cold coiling; Tempering; Hot setting; Hot peening; Shot peening. Investigations revealed that the stress field was axi-symmetrical, that the dominant variation in all samples occurred along the hoop direction (helical circumference), whilst the radial and axial stresses are substantially lower. Accurate two-dimensional stress maps of the rod cross section have been compiled revealing key features associated with the cold coiling step. Comparison of the stress fields after each production step revealed altered stress values. The final shot peening process stage not only reduced stress concentrations at the internal bore, but contributed to the establishment of favourable surface residual stress conditions that enhance the fatigue life of the final product.

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Section: Introductionmentioning

confidence: 99%

Residual Stresses Associated with the Production of Coiled Automotive Springs

Venter

Luzin

Hattingh

2014

MSF

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Effects of Artificial Small Defect and Corrosive Environment on Torsional Fatigue Strength of High Strength Spring Steel

Wakita¹,

Kuno²,

Amano³

et al. 2007

J. Soc. Mat. Sci., Japan

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Study on Predicting Formula for Torsional Fatigue Strength of Spring Steel

Wakita

Kuno

Amano

et al. 2007

Transactions of JSSE

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Torsional fatigue tests were conducted for spring steel SUP7 with smooth surface and artificial pits whose Vickers hardness were 430,480,550 and 620. The effect of notch, hardness and corrosive environment on the fatigue strength was studied. Following conclusions were obtained. (1) The relationship between torsional fatigue strength and hardness in the specimen with smooth surface in air environment was not linear and approximated by third function of hardness revealing the maximum value around 550Hv. (2) The notch factor of torsional fatigue strength in the specimen with artificial pits was the constant value of 1.7 with no relation to hardness and fatigue life in air environment. (3) The notch factor of torsional fatigue strength in the specimen with artificial pits was decreased with the increment of hardness approaching to the value of 1 for long-term fatigue life in corrosive environment. (4) The empirical formulas were derived indicating the fatigue strength in the specimen with artificial pits, the corrosive fatigue strength in the specimen with smooth surface, and the corrosive fatigue strength in the specimen with artificial pits by the third function of hardness.

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Application of High Corrosion Fatigue Strength Spring Material to Cold-Formed Coil Spring

Cited by 3 publications

References 7 publications

Residual Stresses Associated with the Production of Coiled Automotive Springs

Residual Stresses Associated with the Production of Coiled Automotive Springs

Effects of Artificial Small Defect and Corrosive Environment on Torsional Fatigue Strength of High Strength Spring Steel

Study on Predicting Formula for Torsional Fatigue Strength of Spring Steel

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