Effect of iron stearate and heat-treatment conditions on the structure and mechanical properties of powder low-alloy steel

This work investigates the structure and mechanical properties of a powder low-alloy steel after heat treatment (quenching and tempering). The study is carried out on SP50S2KhF steel (powder charge composition, wt %: 94% Fe; 2.5% FS90; 1.5% FkH001; 1.5% FeV; 0.5% C). The original charge also contains iron stearate as a lubricant-plasticizer which is introduced in amounts of 0.5, 1.0, and 3.0 wt %. The most optimal heat treatment conditions that provide for the greatest increase in the strength and hardness of the steel are determined. Iron stearate in the original charge was established to increase the flexural strength of the studied powder steel. The highest value of flexural strength is obtained with the introduction of 3.0 wt % iron stearate. The structure of SP50S2KhF powder steel after heat treatment consists of fine-needled tempering troostite and rounded pores with a size less than 10 μm.