Calculation of the Mixture Flow in a Low-Pressure Carburizing Process

Emilia Wołowiec-Korecka,Piotr Kula,Michał Sut,Agnieszka Brewka,Maciej Korecki

doi:10.3390/met9040439

Emilia Wołowiec-Korecka, Piotr Kula + Show 3 more

Open Access

https://doi.org/10.3390/met9040439

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Journal: Metals	Publication Date: Apr 15, 2019
Citations: 8	License type: CC BY 4.0

Affiliation: Lodz University of Technology, Seco Warwick (Poland)

Abstract

The right selection of carburizing gas flow rates in the low-pressure carburization process is a key factor in terms of its efficiency. However, a correct calculation of the amount of carburizing gas required for uniform carburization of parts, taking into account the process temperature and batch size, is still problematic. For this reason, modern carburizing processes are carried out using an excessive belaying flow of carburizing gases. In this work steel parts (16MnCr5) were carburized in a variable-flow carburizing process (960 °C) individually matched to each segment of saturation. The effect of the variable-flow on the microstructure, surface hardness, and case hardness depth was evaluated and compared to that of a control group. It was proven that the amount of the mixture used in the variable-flow carburizing process can be significantly reduced to 54% of that consumed during the regular constant-flow carburizing without affecting the properties of the hardened layer of the steel parts.

Highlights

Low-pressure carburizing (LPC) is a method of strengthening the surface of the steel
The parts were subjected to a low-pressure carburizing process at a temperature of 960 ◦ C, in a 2:2:1 mixture of acetylene, ethylene, and hydrogen
Individual flows of carburizing gases were applied, that were consistent with the demand for the mixture at a given stage, determined using the following formula [17]: 22.4 7, 870, 000 ·

Summary

Introduction

Low-pressure carburizing (LPC) is a method of strengthening the surface of the steel. Non-treated steel is post-cured in this environment for the time required to obtain the desired carbon profile. Due to the high temperature, the carbon transfer is more efficient in the case of the conventional carburizing method, leading to a shorter carburizing time. Yada and Watanabe reported an LPC process that did not pollute the environment, did not cause intergranular oxidation, and consumed less energy [1]. Kula et al demonstrated carburized steel after quenching and tempering to be multiple times harder than non-treated steel and, as such, to be industrially applicable in those processes where resistance to wear under working conditions is of significance [2]

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