engleski

Modeling of unavoidable residual stresses after transformation-free cooling

Predicting thermal distortions and residual thermal stresses after steel heat treatment from computer simulations is a complex task that involves use a number of process parameters and nonlinear variation of steel properties. Previous studies cooling cylinders without the occurrence of phase transformations in the microstructure indicated the possibility of introducing the dimensionless numbers to predict changes in their dimensions. It was found that the changes in the dimensions of cylinders statistically correlate well with only a few dimensionless numbers that include: shape and dimensions of component, its initial temperature, temperature of the quenching media, heat transfer coefficient, heat conductivity, heat capacity, density, thermal expansion coefficient, Young´s modulus, Poisson´s ratio, yield strength and strain hardening behaviour. The next step in researches is carried out through on a set of numerical simulations with aim to predict the changes of residual stresses of austenitic stainless steels after cooling from the high temperature down to the room temperature. The proposed nonlinear regression model predicts equivalent residual stresses in vicinity of the surface in the half length of long cylinders from a set of autonomous dimensionless numbers.

thermal strains; residual stresses; dimensionless numbers; austenitic steel

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