The effect of grit-blasting on the formation of a carburized layer in the vacuum carburizing

2019 ◽  
Vol 1 (5) ◽  
pp. 4-8
Author(s):  
Kamil Dychtoń
Keyword(s):  
Vacuum Carburizing ◽  
Grit Blasting ◽  
Carburized Layer

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.

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

2015 ◽  
Vol 227 ◽  
pp. 425-428 ◽  
Author(s):  
Kamil Dychtoń ◽  
Paweł Rokicki ◽  
Andrzej Nowotnik ◽  
Marcin Drajewicz ◽  
Jan Sieniawski
Keyword(s):  
Surface Layer ◽  
Chemical Treatment ◽  
Power Transmission ◽  
High Strength ◽  
Aircraft Engine ◽  
Carbon Diffusion ◽  
Process Temperature ◽  
Process Time ◽  
Vacuum Carburizing ◽  
Carburized Layer

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.

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.

Features for formation of diffusion layers during vacuum carburizing of 12Kh2N4A-Sh and 20Kh3MVF-Sh steels

2020 ◽  
pp. 229-233
Author(s):  
V.I. Gromov ◽  
N.A. Kurpyakova ◽  
E.N. Korobova ◽  
A.V. Doroshenko ◽  
A.S. Kuznetsov
Keyword(s):  
Technological Parameters ◽  
Vacuum Carburizing ◽  
Diffusion Layers ◽  
Carburized Layer

The patterns reflecting the influence of controlling technological parameters on the characteristics of the carburized layer during vacuum carburizing of 12Kh2N4A-Sh and 20Kh3MVF-Sh steels are considered. The need is shown to take into account the presence or absence of active carbide-forming elements in the composition of carburizing steels when developing of vacuum carburizing modes.

scholarly journals Effect of Deformation Structure of AISI 316L in Low-Temperature Vacuum Carburizing

Metals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1762
Author(s):  
Hyunseok Cheon ◽  
Kyu-Sik Kim ◽  
Sunkwang Kim ◽  
Sung-Bo Heo ◽  
Jae-Hun Lim ◽  
...  
Keyword(s):  
Low Temperature ◽  
Oxide Layer ◽  
Surface Activation ◽  
Aisi 316L ◽  
Deformation Structure ◽  
Vacuum Carburizing ◽  
Natural Oxide Layer ◽  
Stress Relieving ◽  
Natural Oxide ◽  
Carburized Layer

The effect of plastic deformation applied to AISI 316L in low-temperature vacuum carburizing without surface activation was investigated. To create a difference in the deformation states of each specimen, solution and stress-relieving heat treatment were performed using plastically deformed AISI 316L, and the deformation structure and the carburized layer were observed with EBSD and OM. The change in lattice parameter was confirmed with XRD, and the natural oxide layers were analyzed through TEM and XPS. In this study, the carburized layer on the deformed AISI 316L was the thinnest and the dissolved carbon content of the layer was the lowest. The thickness and composition of the natural oxide layer on the surface were changed due to the deformed structure. The natural oxide layer on the deformed AISI 316L was the thickest, and the layer was formed with a bi-layer structure consisting of an upper Cr-rich layer and a lower Fe-rich layer. The thick and Cr-rich oxide layer was difficult to decompose due to the requirement for lower oxygen partial pressure. In conclusion, the oxide layer is the most influential factor, and its thickness and composition may determine carburizing efficiency in low-temperature vacuum carburizing without surface activation.

Study on bearing stiffness characteristics with residual stress in carburized layer

2020 ◽  
pp. 095440622096079
Author(s):  
Junshuai Liang ◽  
Ning Li ◽  
Jingyu Zhai ◽  
BaoGang Wen ◽  
Qingkai Han ◽  
...  
Keyword(s):  
Residual Stress ◽  
Contact Stiffness ◽  
Roller Bearing ◽  
High Load ◽  
Axial Stiffness ◽  
Fe Model ◽  
Low Load ◽  
Bearing Stiffness ◽  
Carburized Layer ◽  
Stiffness Characteristics

In this study, a layering method of carburized ring is presented. A finite element (FE) model for analyzing bearing stiffness characteristics is established considering the residual stress in the carburized layer. The residual stress in the carburized layer of a double-row conical roller bearing is tested and the influence of the distribution of residual stress in carburized layer on the bearing stiffness is investigated. Results show that the residual stress in the carburized layer increases the contact stiffness of the bearing by 5% in the low-load zone and 3% in the high-load zone. The radial stiffness of the bearing is increased by 5% in the low-load zone and 3% in the high-load zone. The axial stiffness is increased by 6%, and the angular stiffness increased by 4%. The larger the thickness of the carburized layer, the greater the residual compressive stress in the carburized layer, the deeper the position of the maximum residual stresses in the carburized layer will lead to the greater stiffness of the bearing.

scholarly journals Microstructure, Hardness, and Tensile Properties of Vacuum Carburizing Gear Steel

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 300
Author(s):  
Wu Chen ◽  
Xiaofei He ◽  
Wenchao Yu ◽  
Maoqiu Wang ◽  
Kefu Yao
Keyword(s):  
Tensile Properties ◽  
Tensile Tests ◽  
Case Depth ◽  
Strain Hardening Exponent ◽  
Austenitizing Temperature ◽  
Vacuum Carburizing ◽  
Experimental Steel ◽  
Strain Behavior ◽  
Carburized Steel ◽  
Vacuum Carburization

We investigated the effects of the austenitizing temperature on the microstructure, hardness, and tensile properties of case-carburized steel after vacuum carburization at 930 °C and then re-austenitization at 820–900 °C followed by oil quenching and tempering. The results show that fractures occurred early with the increase in the austenitizing temperature, although all the carburized specimens showed a similar case hardness of 800 HV0.2 and case depth of 1.2 mm. The highest fracture stress of 1919 MPa was obtained for the experimental steel when the austenitizing temperature was 840 °C due to its fine microstructure and relatively high percentage of retained austenite transformed into martensite during the tensile tests. We also found that the stress–strain behavior of case-carburized specimens could be described by the area-weighted curves of the carburized case and the core in combination. The strain hardening exponent was about 0.4 and did not vary with the increase in the austenitizing temperature. We concluded that the optimum austenitizing temperature was around 840 °C for the experimental steel.

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