Finite element simulation of fracture toughness testing of 20MnMoNi55 steel and the effect of loading rate on reference temperature

Abstract

Fracture toughness of ferritic steel in the ductile-to-brittle transition zone is scattered and probabilistic owing to embrittlement. Use of master curve along with the reference temperature ( T0) adopted in ASTM E-1921 is widely accepted for characterization of this embrittlement. Reference temperature is a measure of embrittlement in the temperature scale. Factors affecting fracture toughness like geometry and loading rate are expected to influence the reference temperature. In the present study, the role of the loading rate on the reference temperature for 20MnMoNi55 steel is assessed experimentally using compact tension C(T) and three-point bend (TPB) specimens. Finite element simulation of tests at different loading rates and cryogenic temperature are carried out using a suitable viscoplastic material model that incorporates flow characteristics of the material for varying displacement rates and cryogenic temperatures. Results from simulation studies are compared with experimental ones.

Study of Weibull parameters at different loading rates for 20MnMoNi55 steel using Beremin model

“…Here in this study FE-simulation of 1T-CT specimen is done for different rates of loading and temperatures using a suitable material model. It is observed in earlier study [26] that suitable viscoplastic material model can predict better result than elastic–plastic model. This temperature & strain rate sensitive material model was developed with the help of genetic programming.…”

“…Values of Young's Modulus, yield strength and ultimate strength at -100°C in different displacement rates[26].…”