Abstract
Austenitic stainless steels are resistant to rust because of their ability to form a very thin protective film. In addition to corrosion resistance, it has excellent mechanical properties, workability, and heat resistance. Stress corrosion cracking and intercrystalline corrosion can be a problem in austenitic stainless steel products. In order to prevent stress corrosion cracking, solution heat treatment is applied to remove residual stress after plastic forming. After that, annealing at about 400°C is generally carried out. However, some of the various parts are still machined or polished, and the material surface has an affected layer. The effect of heat treatment on materials with an affected layer has not been well investigated. Furthermore, the fatigue strength of heat-treated materials has not been well investigated. In the present study, the effect of shot peening on fatigue strength of low-temperature heat treated stainless steel was investigated. The test materials were four commercially available austenitic stainless steels. The fatigue tests were performed by rotating bending fatigue testing machine. The low-temperature heat treatment temperature was 400°C. Microshot peening was done by an air-type machine. The media was made of cast steel with an average diameter of 0.1 mm. Air pressure and peening time were 0.6 MPa and 60 seconds, respectively. The fatigue strength of the low-temperature heat-treated workpieces increased by 1.3 to 2.7 times compared to that of the untreated workpieces. The fatigue strength of the shot-peened treated workpieces increased by a factor of 1.9 to 3.4 compared to that of the untreated workpieces.
