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Purpose: In this paper, the impact of hardening temperature on the quenching distortions which occur during low-pressure carburizing with gas quenching - using the individual quenching method - was analysed. Design/methodology/approach: The reference elements were subjected to carburizing at 980°C, followed by gas quenching at temperatures of 860°C, 920°C and 980°C. The geometrical measurements of the elements were made before and after the chemical treatment and the size of the quenching distortions of their geometrical parameters was determined. Findings: It was demonstrated that a high temperature of quenching has an unfavourable effect on changes in cylindricity and roundness parameters but, at the same time, reduces the size of distortion of outer parameters. Low temperature quenching reduces quenching distortions of cylindricity and roundness parameters while increasing the distortion of outer dimensions. Research limitations/implications: Based on the research and analysis carried out in this work, it was found that the use of lower quenching temperature is justified in economic and quality terms. Practical implications: In the case of the aviation or automotive industry, very high quality of manufactured elements along with a simultaneous reduction of their production costs is extremely important. Maintaining the dimensions of the elements during heat treatment is extremely difficult. The tests allowed to determine the optimal hardening temperature, which brings with it acceptable deformations. Since it is easier to “repair” the outer geometrical dimensions (diameter, thickness), it seems that quenching from lower temperatures is a more favourable process. Originality/value: The conducted tests allowed to determine the most favourable conditions for hardening elements from the automotive industry, taking into account the occurring deformations and their subsequent processing
EN
The present paper studies and analyzes the low-pressure vacuum carburizing of Pyrowear 53 steel. The carburizing was performed at 921°C. The results after the completion of the treatment process are presented, i.e. microstructure of the surface layer and hardness. The results confirm that carburizing can be effectively used in hardening of the steel.
3
Content available remote Methods of data mining for modelling of low-pressure heat treatment
EN
Purpose: This paper addresses the methods of the modelling of thermal and thermochemical processes used in computer-aided design, optimization and control of processes of thermal and thermochemical treatment in terms of obtaining real-time results of the calculations, which allows for observation of how an item changes during its treatment to respond immediately and to determine the parameters of a corrective process should any irregularities be detected. The main goal of the literature review was to develop a methodology for the design of functional and effective low-pressure processes of thermal and thermochemical treatments using effective calculation methods. Design/methodology/approach: A detailed analysis was conducted regarding the modelling methods with low-pressure carburizing and low-pressure nitriding. Findings: It was found the following criteria of methods selection of heat treatment modelling should be applied: data quality, data quantity, implementation speed, expected relationship complexity, economic and rational factors. Practical implications: Because of its non-equilibrium nature and transient states in the course of the processes computational support is particularly required in low-pressure thermochemical treatments. The primary goal of the simulation is to predict the course of the process and the final properties of the product, what ensures the repeatability of the process results. Originality/value: It was presented a synthetic presentation of modelling methods, in particular methods of artificial intelligence; it was also analysed the possibilities and risks associated with methods.
EN
This paper presents a comparison of the deformations and residual stresses in gear wheels after vacuum carburizing process with quenching in high-pressure nitrogen and oil. The comparison was made on a medium-sized gear wheels, made of AMS6265 (AISI 9310) steel. This steel is applied in the aerospace industry for gears. The study has provided grounds for an assessment of the effect of the method of quenching on the size of deformations. Compared to oil quenching, high-pressure gas quenching following vacuum carburizing resulted in more uniform and smaller deformations.
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