A. M. Freborg, Z. Li, B. L. Ferguson, Deformation Control Technology, Inc., Cleveland, OH
Distortion has been cited as a primary problem for all heat treaters in many surveys of the industry, and remains a primary concern. This presentation reports the use of a simple coupon shape to assess the sensitivity of a steel alloy to the quenching process in terms of residual stress and distortion. Using a rectangular test bar that has a series of grooves machined on one face, carburization and quench hardening trials were conducted. Local distortion was measured along the length of the bar, as well as residual stress using both X-RAY diffraction and Barkhausen noise methods. The analyses were supplemented by use of heat treatment modeling to study the interaction of thermal and transformation strains on resulting distortion and residual stress in the coupons. Data were differentiated by the quenching process conditions. Sensitivity in the analyses was such that both the local dimensions and measured residual stress values were linked to the method and consistency of the quench practice.
Summary: Distortion has been cited as a primary problem for all heat treaters in many surveys of the industry, and remains a primary concern. This presentation reports the use of a simple coupon shape to assess the sensitivity of a steel alloy to the quenching process in terms of residual stress and distortion. Using a rectangular test bar that has a series of grooves machined on one face, carburization and quench hardening trials were conducted. Local distortion was measured along the length of the bar, as well as residual stress using both X-RAY diffraction and Barkhausen noise methods. The analyses were supplemented by use of heat treatment modeling to study the interaction of thermal and transformation strains on resulting distortion and residual stress in the coupons. Data were differentiated by the quenching process conditions. Sensitivity in the analyses was such that both the local dimensions and measured residual stress values were linked to the method and consistency of the quench practice.
