Validation of processing maps for 304L stainless steel using hot forging, rolling and extrusion

Abstract

The development of a microstructure in 304L stainless steel during industrial hot-forming operations, including press forging (mean strain rate of 0.15 s⁻¹), rolling/extrusion (2–5 s⁻¹), and hammer forging (100 s⁻¹) at different temperatures in the range 600–1200°C, was studied with a view to validating the predictions of the processing map. The results have shown that excellent correlation exists between the regimes exhibited by the map and the product microstructures. 304L stainless steel exhibits instability bands when hammer forged at temperatures below 1100°C, rolled/extruded below 1000°C, or press forged below 800°C. All of these conditions must be avoided in mechanical processing of the material. On the other hand, ideally, the material may be rolled, extruded, or press forged at 1200°C to obtain a defect-free microstructure.