Deformation and fracture behavior of 316L sintered stainless steel under various strain rate and relative sintered density conditions

Abstract

This study investigates the effects of the strain rate and the relative sintered density on the mechanical response and fracture behavior of 316L sintered stainless steel. Low strain rate compression tests are conducted on an MTS 810 servohydraulic machine at strain rates of 10 À3 to 10 À1 s À1 , while dynamic impact tests are performed using a split-Hopkinson bar at strain rates of 3 3 10 3 to 9 3 10 3 s À1 . The Taguchi method with an L 9 orthogonal array is used to characterize and optimize the sintering process control factors such that the specimens have three different relative sintered densities, i.e., 83, 88, and 93 pct. It is found that the strain rate and relative sintered density have significant effects on the flow stress, fracture strain, strain rate sensitivity, and activation volume. The significant differences observed in the strain rate sensitivity and activation volume in the high and low strain rate tests indicate that the corresponding deformation is dominated by different rate controlling mechanisms. Furthermore, the changes in strain rate sensitivity and thermal activation volume observed at different levels of the relative sintered density are related to the work hardening stress. At high strain rate and relative sintered densities, slip deformation in the form of slip bands is frequently observed within the grains. Therefore, it appears that higher strain rates and relative sintered densities represent favorable conditions for the formation of shear bands and cracking, and hence lead to premature specimen fracture. The fracture surfaces contain dimplelike structures, which are indicative of a ductile fracture mode. The depth and the density of these dimples decrease as the strain rate and relative sintered density increase, indicating a loss of ductility.

2D Finite Element Modeling of the Cutting Force in Peripheral Milling of Cellular Metals

“…Density The ductile damage model available in ABAQUS/Explicit was used to model material separation during the machining simulation [34][35][36]. The Coulomb friction model (µ = 0.2), commonly used in machining simulations, was used in the present work [37].…”

Modelling flow stress of AISI 316L at high strain rates

“…The significant increase in the flow stress around 10 3 s -1 that has been observed in many metals and alloys has by many researchers been attributed to this phenomena, Guo and Nemat-Nasser (2006), Lesuer et.al (2001), Regazzoni et al (1987). Others argue that the observed increase in the strain rate sensitivity must be an effect of structure evolutions via for example enhanced rate of dislocation generation, twin formation and martensite formation, Follansbee and Kocks (1988), Lee and Chiu (2006).…”

Analysis of the Fatigue Life of Sintered Porous 316L Steel with Different Density

“…The results obtained (i.e., compressive strength, Young's modulus) refer only to the sintered porosity of 40-50%, produced by selective laser sintering and traditional sintering [7]. Another example is the mechanical parameters of sintered 316L stainless steel samples with a relative density of 86-88% or higher (less than 2% porosity) [1,8,9]. However, these materials take into account the results of high density (porosity of the order of several percent), while it would also be desirable to define the mechanical properties of low density agglomerates.…”