Fatigue behavior of bainitic and martensitic super clean Cr–Si high strength steels
Abstract This study compares the fatigue behavior of quenched/tempered and austempered super clean Cr–Si high strength steels (HSS). The microstructure of the quenched and tempered steel consisted of tempered martensite and that of the austempered steel, predominantly lower bainite. Steel samples that were given the two types of heat treatments were fatigue tested in the high cycle fatigue (HCF) regime (105 107). Fatigue crack initiation and propagation modes in samples given the two types of heat treatments were similar. However, those with the lower bainite structure performed better at the highest stress amplitude (500 MPa) used in the study and this was measured in terms of total fatigue life. At lower stress levels (475 MPa and 450 MPa) the total fatigue life of both samples tended to be similar.
1. ::: ::: The antiwear properties of fuels are mainly determined by the amount and character of the adsorption resins contained in the fuel. With increase in content of these, the antiwear properties of the fuels are improved. ::: ::: ::: ::: ::: 2. ::: ::: Mercaptans also exert an effect on the antiwear properties of reaction fuels; with increase in content of these the antiwear properties of fuels become worse. ::: ::: ::: ::: ::: 3. ::: ::: The viscosity of fuels does not exert an important effect on plunger wear in fuel pumps within the range 1.25–1.95 cS at 20°C.