R. M. Huckins, G-M Enterprises, Corona, IL

Summary: This technical paper will discuss the use of controlled directional gas flow in a high-pressure gas quench vacuum furnace to both maximize part hardness uniformity and distortion control. Many critical parts are manufactured from high strength alloys that are prone to distortion. Parts are typically fixtured vertically or horizontally in the heat treat furnace to minimize movement, stresses and maintain a fixed distance between the parts during heating and cooling. Much distortion occurs during quenching due to non-uniform cooling caused by non-uniform gas temperature, too much or too little gas flow or too large a differential gas temperature across the part. Controlled directional gas flow is achieved without any moving parts inside the furnace. This unique design provides excellent dimensional control with high furnace reliability. Distortion prone parts were tested with and without directional gas flow control. The parts, run under directional gas flow control yielded more uniform hardness & reduced distortion.