Flow Stress of Metals and Its Application in Metal Forming Analyses

Abstract

Forming load and energy can be determined if the flow stress of the deforming, material is known at the temperature and strain-rate conditions existing during the process. In this study domestic and foreign melalforming articles were reviewed and the available flow stress data have been presented for selected carbon, stainless, and tool steels; aluminum, copper, and titanium alloys; magnesium, uranium, zircaloy, molybdenum, tungsten, tantalum, and niobium. Whenever possible, data are presented by calculating and tabulating coefficients K and n to express strain hardening (flow stress σ̄ = Kε̄n ), and C and m to express strain-rate dependency (σ̄ = Cε̄̇m). Examples are given to illustrate the use of flow-stress data with simple formulas in predicting pressures in upset forging, closed-die forging, and cold extrusion.