Progress in distortion control through High Pressure Gas Quenching - technology

Low Pressure Carburizing (LPC) in combination with High Pressure Gas Quenching (HPGQ) has been established as an advanced and robust technology for case hardening.

However, as a side-effect of the heat treatment process, the components get distorted. This distortion has a strong cost-impact, because distorted components need to be hard-machined after heat treatment. Therefore, control of distortion and the variation of distortion is a key factor in reducing manufacturing costs.

Heat treat distortion can be significantly reduced by applying the technology of High Pressure Gas Quenching (HPGQ). HPGQ provides a very uniform heat transfer coefficient. The local quenching-effect on the surface of the components is better predictable and more uniform throughout the load. Additional improvements can be achieved by optimizing the gas quenching parameters.

Proper fixturing is another factor for distortion control. Modern CFC-materials (carbon-fiber-reinforced carbon) are well suited as fixture-material for gas quenching. When compared to traditional alloy CFC demonstrates no deflection or distortion after many subsequent years of use.

This paper shows distortion data of various components, demonstrating the effects of optimizing the process parameters and the design of heat treatment fixtures.