Fatigue Test Results of Steel Containing Macroscopic Inclusions under Many-Fold Multiple Load in Two Stress Levels

Abstract

Fatigue test results of the steel containing macroscopic inclusions under many-fold multiple load in two stress levels are presented. The test material is 3%Cr-0.5%Mo alloy steel commonly used for marine turbine rotor shaft. Fatigue tests of large number of cycles up to 10⁸ were conducted. The primary stresses chosen are 1.2^σw and 1.5^σw, in which ^σw is the endurance limit under the constant load amplitude.
The test results indicated that the life of the material containing many macroscopic inclusions of 0.3-0.9 mm in length might be predicted conservatively if the linear damage law would be used, because the value of Σ (n/N) was larger than 1 even when the primary stress was 1.5^σw.