Modeling the Effect of Chemistry Changes on Phase Transformation Timing, Hardness, and Distortion in Carburized 8620 Gear Steel.

AISI 8620 low carbon steel is widely used due to its relatively low cost and excellent case hardening properties. The nominal chemistry of AISI 8620 can have a large range, effecting the phase transformation timing and final hardness of a carburized case. Different vendors and different heats of steel can have different chemistries under the same AISI 8620 range which will change the result of a well-established heat treatment process. Modeling the effects of alloy element variation can save countless hours and scrap costs while providing assurance that mechanical requirements are met. The DANTE model was validated using data from a previous publication and used to study the effect of chemistry variations on hardness and phase transformation timing. Finally, a simplified ring gear model was executed to see the changes in distortion caused by alloy variation within the same heat treatment process.