Effect of V on the tensile strength of sintered Cr-Mo alloyed steel powder compacts

A prealloyed 1Cr-0.3Mo-0.3V(mass%) steel powder was developed to obtain the high strength sintered compacts. This new sintered 1Cr-0.3Mo-0.3V powder compact, which is Mn-less, made it possible to extend the range of the cooling rate after sintering to attain higher strength than that of sintered 1Cr-0.3Mo steel, and gave a tensile strength of more than 800 MPa and a rotating bending fatigue strength of 310MPa at the cooling rates of 1 to 30°C/min. The wide range of cooling rates at which high strength can be obtained was attributed to a decrease in hardenability and the production of a fine pearlite structure by V addition. The improvement of the strength for the compacts added V is attributed to the precipitation hardening of V carbonitrides, as well as a narrow pearlite lamellar spacing.