Minimizing Stress and Distortion for Shafts and Discs by Controlled Quenching in a Field of Nozzles

Abstract

A coupled gas-dynamical and thermo-mechanical model for simulation of the gas flow, gas and specimen temperature, phase, stress, strain, and displacement transient-fields during quenching of cutting discs and shafts of steel is introduced. The material properties (e. g. density, conductivity, heat capacity, hardness) are obtained by homogenization procedures. The material behaviour is described as an extension of the classical J 2 -plasticity theory with the extension of temperature and phase fraction dependent yield criteria. The coupling effects such as dissipation, phase transformation enthalpy, and transformation induced plasticity (TRIP) are considered. Simulations were carried out for cutting discs of knives, and for shafts made of steel SAE 52100 with varying diameter. For the validation of the simulations, these work pieces were heated in a roller hearth kiln up to 850 C, and than quenched in a field of nozzles in which the heat transfer coefficient was known and could be locally adjusted by the volume flow of each nozzle. The phase fractions, surface hardness, distortion, and residual stresses were measured. The simulated and measured results fit quite well. According to optimization-simulations the shafts were quenched with a certain heat transfer coefficient distribution. The bigger diameter parts of the shaft were more intensively quenched by an increased gas flow so that the hardness profiles were equalized and the residual stresses at the edges were significantly reduced.Keywords

Sensitivity of material properties on distortion and residual stresses during metal quenching processes

“…Our previous works (Pietzsch et al, 2005(Pietzsch et al, , 2007Brzoza et al, 2006;Kaymak and Specht, 2007;Kaymak, 2007;Nallathambi et al, 2008) are focused to the optimum cooling strategies through a modified HTC profile which reduces the distortion and residual stresses simultaneously. Apart from the external parameters which control the quenching process, the internal parameters which significantly dominate in the quenching process are the material properties.…”

Integrated fluid-thermal-structural numerical analysis for the quenching of metallic components

“…Due to the studies on the theory and the numerical simulation of the individual events that occur during quenching and the computational method for fast and accurate prediction of the multi-physical phenomenon in the last three decades, the simulation of quenching process became realistic and several commercial software packages had been developed to be capable of simulating quenching process, such as DANTE, DEFORM-HT, FORGE, HEARTS, SYSWELD and Quench Simulator. However, most studies consider the quenching process as a thermalmicrostructural-mechanical problem [1][2] and these software are incapable of coupling with dynamic characteristics of fluid in quenching tank, which determines the local cooling rate at part surfaces.Coupling quenching simulations with computational fluid dynamics (CFD) is a major interest [8][9] . However, fluid-thermal simulation in most of the research is focused on single phase liquid or gas quenching.…”

“…Coupling quenching simulations with computational fluid dynamics (CFD) is a major interest [8][9] . However, fluid-thermal simulation in most of the research is focused on single phase liquid or gas quenching.…”

Distortion and Residual Stresses during Metal Quenching Process

“…The complex mechanism behind the residual stress evolution during the quenching process is well explained by Todinov [3]. References [4][5][6][7][8] give more information about the distortion and residual stress calculation during metal quenching. This article is arranged in the following manner: Section 2 presents the mathematical formulation of the three physical fields.…”

“…As the phase transition penetrates through the legs, the distortion again changes its direction and the profile bends toward the legs one more time (2-3-4). Finally, the phase transition is completed throughout the profile and the distortion gradually decreases as the temperature becomes uniform (4)(5). However, a permanent deformation remains due to the mechanical yielding and transformation induced plasticity.…”