Mechanical characterization by traction and small punch tests of ultra-fine grained AISI 316L with bimodal grain size distributions

Abstract

In this paper, the mechanical behavior of austenitic stainless steel 316L with ultrafine grains is investigated using monotonic tensile tests and small punch tests at various temperatures ranging from 20 to 500 °C. Samples were elaborated by powder metallurgy coupled with spark plasma sintering with both unimodal and bimodal grain size distributions. The latter case is obtained by mixing two different powders. The ratio between the largest and lowest grain size was set to 50 and three different volume fractions (i.e. 25, 50 and 75%) of grains with conventional size were investigated. Results show that the bimodal grain size distribution increases the fracture strain to failure in tensile conditions but no effect is observed for small punch tests at room temperature. For these micro forming tests, the temperature elevation tends to reduce the differences between unimodal and bimodal specimens.In this paper, the mechanical behavior of austenitic stainless steel 316L with ultrafine grains is investigated using monotonic tensile tests and small punch tests at various temperatures ranging from 20 to 500 °C. Samples were elaborated by powder metallurgy coupled with spark plasma sintering with both unimodal and bimodal grain size distributions. The latter case is obtained by mixing two different powders. The ratio between the largest and lowest grain size was set to 50 and three different volume fractions (i.e. 25, 50 and 75%) of grains with conventional size were investigated. Results show that the bimodal grain size distribution increases the fracture strain to failure in tensile conditions but no effect is observed for small punch tests at room temperature. For these micro forming tests, the temperature elevation tends to reduce the differences between unimodal and bimodal specimens.