scholarly journals The Effect of the Quenching Method on the Deformations Size of Gear Wheels after Vacuum Carburizing

2016 ◽  
Vol 61 (2) ◽  
pp. 1057-1062 ◽  
Author(s):  
K. Dybowski ◽  
J. Sawicki ◽  
P. Kula ◽  
B. Januszewicz ◽  
R. Atraszkiewicz ◽  
...  
Keyword(s):  
High Pressure ◽  
Residual Stresses ◽  
Aerospace Industry ◽  
Vacuum Carburizing ◽  
Gas Quenching ◽  
Quenching Method ◽  
Gear Wheels ◽  
Carburizing Process

Abstract 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.

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

2016 ◽  
Vol 61 (4) ◽  
pp. 2009-2012 ◽  
Author(s):  
P. Rokicki ◽  
K. Dychton
Keyword(s):  
Chemical Treatment ◽  
Negative Impact ◽  
Aerospace Industry ◽  
Tool Steels ◽  
Vacuum Carburizing ◽  
Layer Characteristic ◽  
Process Methodology ◽  
Carburized Layer ◽  
Treatment Procedures ◽  
Carburizing Process

Abstract Carburizing is one of the most popular and wide used thermo-chemical treatment methods of surface modification of tool steels. It is a process based on carbon diffusive enrichment of the surface material and is applied for elements that are supposed to present higher hardness and wear resistance sustaining core ductility. Typical elements submitted to carburizing process are gears, shafts, pins and bearing elements. In the last years, more and more popular, especially in highly advanced treatment procedures used in the aerospace industry is vacuum carburizing. It is a process based on chemical treatment of the surface in lower pressure, providing much higher uniformity of carburized layer, lower process cost and much lesser negative impact on environment to compare with conventional carburizing methods, as for example gas carburizing in Endo atmosphere. Unfortunately, aerospace industry requires much more detailed description of the phenomena linked to this process method and the literature background shows lack of tests that could confirm fulfilment of all needed requirements and to understand the process itself in much deeper meaning. In the presented paper, authors focused their research on acetylene flow impact on carburized layer characteristic. This is one of the most crucial parameters concerning homogeneity and uniformity of carburized layer properties. That is why, specific process methodology have been planned based on different acetylene flow values, and the surface layer of the steel gears have been investigated in meaning to impact on any possible change in potential properties of the final product.

Investigating Fatigue Strength of Vacuum Carburized 17CrNi6-6 Steel Using a Resonance High Frequency Method

2014 ◽  
Vol 225 ◽  
pp. 45-52 ◽  
Author(s):  
Piotr Kula ◽  
Konrad Dybowski ◽  
Sebastian Lipa ◽  
Robert Pietrasik ◽  
Radomir Atraszkiewicz ◽  
...  
Keyword(s):  
High Pressure ◽  
Fatigue Strength ◽  
High Frequency ◽  
Vacuum Carburizing ◽  
Frequency Method ◽  
Single Degree Of Freedom ◽  
Bending Fatigue ◽  
Single Degree ◽  
Bending Fatigue Strength ◽  
Frequency Changes

The bending fatigue strength of 17CrNi6-6 steel subjected to vacuum carburizing with high pressure gas hardening has been measured using a novel high-frequency technique. The test records the changes in resonance and consists of observing resonance frequency changes in a vibrating system with a single degree of freedom as a result of the forming of a fatigue crack. Moreover, a mechanism of fatigue nucleation and propagation in steel hardened by vacuum carburizing is presented.

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

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 694 ◽  
Author(s):  
Jacek Sawicki ◽  
Krzysztof Krupanek ◽  
Wojciech Stachurski ◽  
Victoria Buzalski
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
High Pressure ◽  
Heat Transfer Coefficient ◽  
Fluid Flow ◽  
Transfer Coefficient ◽  
Single Piece ◽  
Gas Quenching ◽  
Complex Fluid ◽  
Algorithm Scheme

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.

The influence of hardening medium in the vacuum carburizing process on the distortion of machine elements used in the automotive industry

2019 ◽  
Vol 1-2 (94) ◽  
pp. 32-40 ◽  
Author(s):  
S. Pawęta ◽  
R. Pietrasik
Keyword(s):  
Automotive Industry ◽  
Gas Pressure ◽  
Furnace Chamber ◽  
Optimal Parameters ◽  
Vacuum Carburizing ◽  
Dimensional Changes ◽  
Process Gas ◽  
Hardening Process ◽  
Gas Quenching ◽  
Reducing Costs

Purpose: As part of this study, the influence of the hardening medium on distortions of FineCarb® carburized rollers used in the automotive industry as elements of fuel pumps has been examined. The analysis was carried out for the process of quenching in gas at different pressure of cooling gas and quenching in oil at variable delay time of oil mixers. Design/methodology/approach: The research was carried out on real elements used in the automotive industry as elements of fuel pumps. FineCarb® vacuum carburizing technology was used in order to obtain optimal parameters of the surface layers. During quenching a variable related to the parameters of the quenching medium was introduced. For quenching in gas it was the pressure at which nitrogen was introduced into the cooling chamber, while for quenching in oil it was the time of mixers delay. The sample batch was laid out in accordance with the PPAP (Production Part Approval Process) requirements for the automotive industry. Microhardness and radial runout measurements were carried out on the samples and subjected to statistical analysis. Findings: The analysis of each hardening processes has showed that depending on the cooling medium used, different distortion values are obtained. The distortion value is significantly influenced by the parameters of the hardening process – gas pressure/oil mixers delay. With the proposed quenching parameters, there is no relationship between the location of the sample in the furnace chamber and the distortion value. The smallest hardening distortions were obtained as a result of the hardening process in gas at a gas pressure of 3 bar. Hardening in gas was characterized by the smallest scatter values of obtained results of radial runout. Research limitations/implications: Basing on the studies and analyses carried out in this work, it can be concluded that the introduction of gas quenching technology instead of oil quenching technology is justified qualitatively and economically alike. Hardening in gas was also characterized by the smallest scatter values of obtained results of radial runout. This is an extremely important technological and economic aspect, due to the cost of grinding processing. Practical implications: The automotive and aviation industries are putting ever greater demands on the quality of manufactured components while reducing costs. Volume 94 • Issues 1-2 • May-June 2019 It requires optimization of technological processes from co-operators. In the case of hardening plants, the most important aspect is obtaining repeatable, precisely planned parameters of the carburized layer, as well as minimizing the negative phenomena that cause dimensional changes after hardening of elements. The tests allowed to determine the most effective hardening conditions in terms of obtained distortions and costs of eliminating distortions. However, the selection of the optimal parameters depends on whether the core hardness requirements are also determined. Originality/value: The conducted tests allowed to determine the most effective hardening conditions in terms of obtained distortions, costs of levelling distortions and a complete technological process for the automotive industry.

Determination of the Residual Stress State of High-Pressure Nozzles During Diamond Smoothing

2020 ◽  
pp. 3-11
Author(s):  
S.A. Zaides ◽  
A.N. Mashukov
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
Stress State ◽  
Residual Stresses ◽  
Element Model ◽  
Depth Of Penetration ◽  
Residual Stress State ◽  
Hardening Treatment ◽  
Cylindrical Parts ◽  
Smoothing Process

The paper presents the results of a study that examines modelling of the polishing and hardening treatment of axisymmetric cylindrical parts such as high-pressure fittings with metal seals on the pipe and the rod. A finite element model of the diamond smoothing process was developed, which allowed one to determine the stress state in the deformation zone depending on the feed rate, tool deflection angle, pressing force, and depth of penetration into the material of the part. The analysis of the modelling results helped to identify a range of optimal modes for diamond smoothing. By using finite element modelling in ANSYS Workbench Mechanical it was possible to test those smoothing modes that were difficult to test experimentally. The study identified the most significant factors that influenced the formation of the maximum values of residual stresses in the surface layer of gate assemblies of high-pressure valves. The maximum values of compressive residual stresses, the value of which did not exceed the yield strength of the material were determined.

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