Analysis On The Mechanical Properties Of 316L Stainless Steel

A creasing number of 316L stainless steels are applied in construction and aviation fields on account of its corrosion resistance and mechanical and processing properties. Besides its high costs in initial period, 316L stainless steels' combined costs are lower than the ordinary steel structures because of its low maintenance costs,long service life and recycle materials. In the process of machinery, while the low thermal conductivity and the great toughness of stainless steels leads to serious surface hardening and high cutting temperature at the tip of knives problems, which have a great impact on the integrity and surface quality of materials processing. As a significant characteristic in reflecting material mechanics properties,the constitutive relation of materials has extensive applications in the construction of mechanical model.This paper analyzes the mechanical properties of 316L stainless steels in quasi-static,intermediate strain rate and high strain rate experiments and fracture toughness experiment using cooled and hardened specimens after machining, and improves the experimental methods. In the meanwhile, the calculation of fracture toughness of three point bending specimens with the same size by the finite element software in both experiments and simulations,and the observation of crack phenomenon of specimens by digital speckle correlation method are also mentioned in this paper.The main contents of this paper are as follows:(1). Quasi-static stretching and compression experiment on 316L stainless steel samples after machining referring to relevant experimental standards using universal material testing machine, and torsion experiment on specimen by torsion testing machine to measure its mechanical property parameters under the quasi-static state.(2). Impact tensile experiment and Charpy pendulum impact test on 316L metal specimen under intermediate strain rate using Zwick-Roell instrumented impact testing machine to obtain its engineering stress and strain curve under the strain rate, and further get the true stress-strain curve based on volume invariable assumptions. Meanwhile, Charpy pendulum test was completed to analyze the plasticity of materials.(3). Impact compression test on specimens at high strain rate using Split Hopkinson Pressure Bar and stress and strain curve calculated by three-wave method are used to calculate its Johnson-Cook constitutive model parameters.(4). After adopting fatigue precracking on three-point bending specimens by electrohydraulic servo tester, quasi-static three-point bending test was conducted by universal material testing machine to measure its quasi-static fracture property parameters, and the impact three-point bending test was implemented to measure its dynamic fracture toughness parameters through numerical method. Also, analyzing sprayed speckles and detecting the change of strain field at the crack tip on sample surfaces using digital image correlation method are all necessary.