Effect of inclusion type on the rotating bending fatigue properties of a high carbon chromium bearing steel

The use of the double vacuum melting route (conventional second refining + vacuum arc refining, CSR+VAR) and the electroslag remelting route (vacuum induction melting + electroslag remelting, VIM+ESR)) has been investigated for the SAE52100 (100Cr6) bearing steel. The tensile properties, impact toughness, hardness and RCF life of the CSR+VAR steel and the steel prepared using the VIM+ESR route are similar. The number and size of TiN inclusions in the VIM+ESR steel are higher and larger than those in the CSR+VAR steel, providing an explanation for the observation of better fatigue properties for the CSR+VAR steel. Two major types of inclusions, magnesium aluminates/Al2O3-CaO-CaS and TiN, are located in different areas in a map of stress intensity factor versus rotatory bending fatigue cycles (NRBF). The negative impact of TiN inclusions on fatigue properties are greater than those of magnesium aluminates/Al2O3-CaO-CaS inclusions.