Process Temperature Effect on Surface Layer of Vacuum Carburized Low-Alloy Steel Gears

Abstract

Gears, due to their complex shape, carried load and required accuracy are ones of most complex aircraft engine parts. Single tooth damage usually breaks the power transmission and causes failure of the entire gear system. Adequate sustainability and guarantees of transmission is therefore a condition for secure operation of whole device. Particularly high requirements for reliability are put to transmissions used in the aerospace industry. Due to the loads which are transmitted through the gears, the materials used by the manufacturer must have not only high strength but also show the abrasion resistance of the surface layer and the ductility of the core. Thermo-chemical treatment of industrial gears is a fundamental process, which gives them adequate mechanical properties regarding loads they carry and the surface conditions of work. The most promising method in the discussed field is vacuum carburizing, which by its specification of work significantly reduce the emission of CO2and the duration of the process, without reducing the quality of the final product. The main aim of the paper is to present criteria for selection of carburizing parameters (mainly temperature increase) as a part of thermo-chemical treatment process performed using vacuum methods. Proper (higher to compare with conventional methods) carburizing process temperature is crucial in programming of carbon diffusion process meaning in process time and final carburized layer characteristics as carbon profile and homogeneity of the carburized layer.

Study of the Catalytic Strengthening of a Vacuum Carburized Layer on Alloy Steel by Rare Earth Pre-Implantation

“…Vacuum carburization, as a surface strengthening method, plays an important role in the process of obtaining excellent comprehensive mechanical properties of 20Cr2Ni4A alloy steel. Vacuum carburization is a rapid process in which acetylene is injected into a high-temperature furnace in pulsed mode under low pressure and vacuum [6,7,8]. However, vacuum carburizing still has its disadvantages, such as a high carburizing temperature, a long carburizing cycle, an uneven structure, and coarse carbide particles.…”

Microstructure and hardness of Pyrowear 53 steel after low-pressure vacuum carburizing at 921°C

“…The schematic view of the heat treatment of LPC process.Low-pressure carburizing (LPC) process is a type of vacuum thermo-chemical treatment cess that create technological top layer[1]. Vacuum carburizing process is a selfulating process, consisting of cyclic saturation and diffusion intervals[2].The thematical models of the process created with numerical simulations are a basic tool for trolling the carburizing process[3,4]-carbon concentration control. Vacuum carburizing non-equilibrium process-intensive carbon saturation as a substrate on the surface of the terial occurs[5][6][7].…”

Acetylene Flow Rate as a Crucial Parameter of Vacuum Carburizing Process of Modern Tool Steels

“…As vacuum carburizing have been already successfully introduced in the automotive field, aviation sector is still on the level of implementation, bothering with problematic homogeneity of the carburized layer and reproducibility of obtained by conventional methods results. That is why, research laboratories develop this method of thermochemical treatment for steel materials to meet all the requirements, especially taking into account ones in the aviation industrial sector [5].…”