AbstractThe development of microstructure in 316L stainless steel during industrial hot forming operations including press forging (strain rate of 0·15 s−1), rolling/extrusion (strain rate of 2–8·8 s−1), and hammerforging (strain rate of 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 showed that good correlation existed between the regimes indicated in the map and the product microstructures. The 316L stainless steel exhibited unstable flow in the form of flow localisation when hammer forged at temperatures above 900°C, rolled below 1000°C, or pressforged below 900°C. All these conditions must therefore be avoided in mechanical processing of the material. Conversely, in order to obtain defect free microstructures, ideally the material should be rolled at temperatures above 1100°C, press forged at temperatures above 1000°C, or hammer forged in the temperature range 600–900°C.MST /3469