
Investigation and Development Status of the Application Technology to Improve Fatigue Behavior of High Strength Alloys
Zhao Zhenye
Strategic Study of CAE ›› 2005, Vol. 7 ›› Issue (3) : 90-94.
Investigation and Development Status of the Application Technology to Improve Fatigue Behavior of High Strength Alloys
Zhao Zhenye
Investigation and development status of the surface integrity application technology to improve fatigue behavior of high strength aluminium alloy, titanium alloy and ultra-high strength steels is reviewed. Fatigue behavior of the high strength alloys mentioned above is sensitive to surface stress concentration, as that in the case of a reduction in the surface integrity, their fatigue stress and stress corrosion property are reduced heavily by surface residual tensile stress and damage caused by abusive final mechanical processes such as grind, particularly the machining heat which occurs during machining practice. Some advanced mechanical treatments in surface integrity make an outstanding improvement on fatigue behavior of the high strength alloys. For example an increase of about 89% , in the tensile-tensile fatigue life for laser-shocked 7475-T761 specimens and an improvement in da/dN of about 1500 times for laser-shocked 7070-T76 specimens were obtained. Ultrasonic shot peening resulted in low-cycle fatigue strength increase of about 50% for HP-310 grade ultra-high strength steel and about 15% for Ti7A14Mo in high-cycle. An advanced surface duplex hardening treatment caused also a 30 to 35-fold increase in contact fatigue life for vasco X-2 grade gear steel.
high strength alloys / surface integrity / laser-shocking / surface duplex hardening
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