Vacuum carburizing—process optimization

2005 ◽  
Vol 164-165 ◽  
pp. 876-881 ◽  
Author(s):  
P. Kula ◽  
R. Pietrasik ◽  
K. Dybowski
Keyword(s):  
Process Optimization ◽  
Vacuum Carburizing ◽  
Carburizing Process

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.

Modeling of Growth and Dissolution of Grain Boundary Cementite in Vacuum Carburizing Process

2011 ◽  
Vol 172-174 ◽  
pp. 1177-1182
Author(s):  
Hideaki Ikehata ◽  
Kouji Tanaka ◽  
Hiroyuki Takamiya ◽  
Hiroyuki Mizuno
Keyword(s):  
Retained Austenite ◽  
Calphad Method ◽  
Metastable Equilibrium ◽  
Low Alloy Steels ◽  
Square Root ◽  
Vacuum Carburizing ◽  
Lattice Constants ◽  
Moving Interface ◽  
Alloy Steels ◽  
Carburizing Process

In order to predict microstructures during vacuum carburizing, the model which simulates not only the carbon(C) diffusion but also growth/dissolution of cementite(θ) is required. For development of a new model we applied vacuum carburizing to low alloy steels and analyzed the distribution of C and θ by GD-OES and image analysis of microstructures. The C in retained austenite(γ) phase after carburizing was also measured by lattice constants obtained from XRD. We also simulated multi-component diffusion with γ matrix and θ layer to analyze a velocity of the moving interface. The new carburizing model was proposed based on the findings, which suggest that C in γ phase at the carburizing surface is supersaturated and corresponds to C concentration for metastable equilibrium condition to graphite. The growth and dissolution of the θ follow a square root of time with the coefficients controlled by diffusion of Si in γ and Cr in θ respectively. The required parameters such as diffusivity coefficients are obtained by the CALPHAD method. The calculated C distributions and volume fractions of θ represent the experimental results.

Experimental Study on Vacuum Carburizing Process for Low-Carbon Alloy Steel

2013 ◽  
Vol 23 (2) ◽  
pp. 545-550 ◽  
Author(s):  
Shaopeng Wei ◽  
Gang Wang ◽  
Xianhui Zhao ◽  
Xiaopeng Zhang ◽  
Yiming Rong
Keyword(s):  
Experimental Study ◽  
Alloy Steel ◽  
Low Carbon ◽  
Vacuum Carburizing ◽  
Carburizing Process

scholarly journals Mechanism of Carbon Infiltration in Vacuum-Carburizing Process

DENKI-SEIKO ◽  
2006 ◽  
Vol 77 (1) ◽  
pp. 5-9 ◽  
Author(s):  
Toshiyuki Morita ◽  
Koichiro Inoue ◽  
Tomoki Hanyuda
Keyword(s):  
Vacuum Carburizing ◽  
Carburizing Process

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

Coatings ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1003
Author(s):  
Jingyu Guo ◽  
Xiaohu Deng ◽  
Huizhen Wang ◽  
Leyu Zhou ◽  
Yueming Xu ◽  
...  
Keyword(s):  
Carbon Concentration ◽  
Surface Hardness ◽  
Low Pressure ◽  
Diffusion Time ◽  
Vacuum Carburizing ◽  
Surface Carbon ◽  
Gear Steel ◽  
Simulated Surface ◽  
Carburized Layer ◽  
Carburizing Process

A combination of simulation and experimental approaches to optimize the vacuum carburizing process is necessary to replace the costly experimental trial-and-error method in time and resources. In order to accurately predict the microstructure evolution and mechanical properties of the vacuum carburizing process, a multi-field multi-scale coupled model considering the interaction of temperature, diffusion, phase transformation, and stress was established. Meanwhile, the improved model is combined with the heat treatment software COSMAP to realize the simulation of the low-pressure vacuum carburizing process. The low-pressure vacuum carburizing process of 20CrMo gear steel was simulated by COSMAP and compared with the experimental results to verify the model. The results indicated that the model could quantitatively obtain the carbon concentration distribution, Fe-C phase fraction, and hardness distribution. It can be found that the carbon content gradually decreased from the surface to the center. The surface carbon concentration is relatively high only after the carburizing stage. With the increase in diffusion time, the surface carbon concentration decreases, and the carburized layer depth increases. The simulated surface carbon concentration results and experimental results are in good agreement. However, there is an error between calculations and observations for the depth of the carburized layer. The error between simulation and experiment of the depth of carburized layer is less than 6%. The simulated surface hardness is 34 HV lower than the experimental surface hardness. The error of surface hardness is less than 5%, which indicates that the simulation results are reliable. Furthermore, vacuum carburizing processes with different diffusion times were simulated to achieve the carburizing target under specific requirements. The results demonstrated that the optimum process parameters are a carburizing time of 42 min and a diffusion time of 105 min. This provides reference and guidance for the development and optimization of the vacuum carburizing process.

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.

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