Modeling of Dimensional Changes and Residual Stresses After Transformation-Free Cooling

Landek, Darko and Lisjak, Dragutin and Lübben, Thomas and Župan, Josip (2014) Modeling of Dimensional Changes and Residual Stresses After Transformation-Free Cooling. = Modeling of Dimensional Changes and Residual Stresses After Transformation-Free Cooling. Materials Performance and Characterization, 3 (4). pp. 99-117. ISSN 2165-3992. Vrsta rada: ["eprint_fieldopt_article_type_article" not defined]. . Točan broj autora: 4.

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Official URL: https://doi.org/10.1520/MPC20140005

Abstract

Predicting thermal distortions and residual stresses after steel heat treatment is a complex task which solution involves the use of a number of process parameters and nonlinear variation of steel properties. Former investigations in transformation-free cooling processes of long cylindrical work pieces in a gas nozzle field showed a typical behavior of the dimensional changes which indicated the possibility of introducing dimensionless numbers to predict thermal distortions. It was found that the changes in the dimensions of cylinders correlate well with only a few dimensionless numbers which are defined as function of shape and dimensions of components, 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 behavior. For a systematic investigation of impacts on dimensional changes and residual stresses after transformation-free cooling a representative group of 28 austenitic stainless steels was selected from literature. Their properties were statistically analyzed and three representative combinations of steel properties have been selected. The numerical simulations were carried out by use of the commercial finite element (FE) program SYSWELD® 2005 with the aim to predict residual stresses and change of dimensions of a long cylinder made of austenitic stainless steel after gas cooling from the high temperature down to room temperature. The FE results were analyzed with the nonlinear regression methods and with genetic programming methods. From these analyses two dimensionless mathematical models were proposed, one for prediction of thermal distortions and the other for prediction of equivalent residual stresses. The proposed dimensionless regression models allow the portability of the calculation results to similar cooling conditions (temperature independent heat transfer) for a transformation-free cooling of long cylinders made from any austenitic steel selected from the considered representative group of steels.

Item Type: Article (["eprint_fieldopt_article_type_article" not defined])
Keywords (Croatian): transformation-free cooling, thermal strains, residual stresses, dimensionless numbers, austenitic steel
Subjects: TECHNICAL SCIENCE > Mechanical Engineering
Divisions: 1000 Department of Materials > 1010 Chair of Materials and Tribology
1000 Department of Materials > 1020 Chair of Heat Treatment and Surface Engineering
700 Department of Industrial Engineering > 720 Chair of Production Control
Indexed in Web of Science: No
Indexed in Current Contents: No
Date Deposited: 06 May 2016 12:03
Last Modified: 21 Feb 2018 09:58
URI: http://repozitorij.fsb.hr/id/eprint/5788

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