Algorithm Scheme to Simulate the Distortions during Gas Quenching in a Single-Piece Flow Technology

Abstract

Low-pressure carburizing followed by high-pressure quenching in single-piece flow technology has shown good results in avoiding distortions. For better control of specimen quality in these processes, developing numerical simulations can be beneficial. However, there is no commercial software able to simulate distortion formation during gas quenching that considers the complex fluid flow field and heat transfer coefficient as a function of space and time. For this reason, this paper proposes an algorithm scheme that aims for more refined results. Based on the physical phenomena involved, a numerical scheme was divided into five modules: diffusion module, fluid module, thermal module, phase transformation module, and mechanical module. In order to validate the simulation, the results were compared with the experimental data. The outcomes showed that the average difference between the numerical and experimental data for distortions was 1.7% for the outer diameter and 12% for the inner diameter of the steel element. Numerical simulation also showed the differences between deformations in the inner and outer diameters as they appear in the experimental data. Therefore, a numerical model capable of simulating distortions in the steel elements during high-pressure gas quenching after low-pressure carburizing using a single-piece flow technology was obtained, whereupon the complex fluid flow and variation of the heat transfer coefficient was considered.

Modeling and Simulation of Vacuum Low Pressure Carburizing Process in Gear Steel

“…Vacuum carburizing is an important heat treatment process for gear surface strengthening, which makes the gear surface have a specific carbon concentration and improves the surface hardness of the workpiece after quenching treatment. The ultimate goal is to improve the bearing capacity and service life of gears [2][3][4][5]. In recent years, vacuum carburizing as an environmentally friendly heat treatment process has received widespread attention.…”

Mathematical Modeling of Carbon Flux Parameters for Low-Pressure Vacuum Carburizing with Medium-High Alloy Steel

“…Low-pressure carburization especially combined with high-pressure gas quenching is a new technology that allows accurate control over the carbide morphology, size, distribution, surface carbon content, and layer depth [1][2][3]. It also offers energy savings and environmental protection and is being applied to various gear steels.…”