scholarly journals Formation of Complex Inclusions in Gear Steels for Modification of Manganese Sulphide

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2051
Author(s):  
Haseeb Ahmad ◽  
Baojun Zhao ◽  
Sha Lyu ◽  
Zongze Huang ◽  
Yingtie Xu ◽  
...  
Keyword(s):  
Oxide Inclusion ◽  
Size Composition ◽  
Average Diameter ◽  
Formation Mechanisms ◽  
Calcium Treatment ◽  
Oxide Inclusions ◽  
Gear Steel ◽  
Calcium Aluminates ◽  
Gear Steels ◽  
Micro Analysis

Suitable MnS inclusions in gear steel can significantly improve the steel machinability and reduce the manufacturing costs. Two gear steel samples with different sulphur contents were prepared via aluminium deoxidation followed by calcium treatment. The shape, size, composition and percentage distribution of the inclusions present in the steel samples were analyzed using an electron probe micro-analysis (EPMA) technique. The average diameter of MnS precipitated on an oxide inclusion is less than 5 µm. It was found that the steel with high sulphur content contains a greater number of elongated MnS precipitates than low sulphur steel. Moreover, there are more oxide inclusions such as calcium-aluminates and spinels with a small amount of solid solution of (Ca,Mn)S in low content sulphur steel after calcium treatment, which indicates the modification of solid alumina inclusions into liquid aluminates. The typical inclusions generated in high sulphur steel are sulphide encapsulating oxide inclusions and some core oxides were observed as spinel. The formation mechanisms of complex inclusions with different sulphur and calcium contents are discussed. The results are in good agreement with thermodynamic calculations.

Application of Calcium Treatment to Sulfur Gear Steel 20CrMo

2014 ◽  
Vol 936 ◽  
pp. 1323-1328
Author(s):  
Xiao Dong Wu ◽  
Dao Xin Zhang ◽  
Rui Long Chen
Keyword(s):  
Continuous Casting ◽  
Thermodynamic Calculation ◽  
Rolled Steel ◽  
Calcium Treatment ◽  
Melting Compound ◽  
Gear Steel ◽  
Calcium Aluminates ◽  
Sulfide Compound ◽  
Higher Temperature

Based on the thermodynamic calculation, the conditions of calcium treatment to sulfur gear steel are analyzed and the samples of rolled steel are studied. Results show that Calcium treatment to melting steel after RH refining can make the sulfide inclusions and calcium aluminates bind together and form the spindle shaped low melting compound inclusions. In the meanwhile, controlling of w (O) in steel below 0.0012% before calcium treatment is more beneficial to modify the Al2O3 and sulfide by the added calcium and to form the oxide-sulfide compound inclusions only if w (AlS) in steel is adjusted to 0.015%~0.025% before continuous casting. The Ca wire should also be fed at higher temperature.

scholarly journals Bending Fatigue Behaviors Analysis and Fatigue Life Prediction of 20Cr2Ni4 Gear Steel with Different Stress Concentrations near Non-metallic Inclusions

Materials ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3443 ◽  
Author(s):  
Zhiguo Xing ◽  
Zhiyuan Wang ◽  
Haidou Wang ◽  
Debin Shan
Keyword(s):  
Fatigue Life ◽  
Quantitative Analysis ◽  
Steel Production ◽  
The State ◽  
Heavy Duty ◽  
Stress Concentrations ◽  
Bending Fatigue ◽  
Gear Steel ◽  
Gear Steels ◽  
The Relationship

To investigate the relationship between inclusions and bending fatigue behaviors in 20Cr2Ni4 steel under different stress concentrations. This paper designs a new experimental method to prefabricate different size stress concentrations near the inclusions, and then conducts a new type of bending fatigue test to study the inclusions and their surrounding stress distributions in 20Cr2Ni4 steel. A microhardness tester was combined with laser etching equipment to realize the prefabrication of different stress concentrations at arbitrary positions around any inclusion on the gear steel surface. This method provides an experimental basis for the quantitative analysis of the relationship between stress distribution and fatigue life around the inclusions of heavy-duty gear steels. We also predict the bending fatigue lives of heavy-duty gear steels with different types of inclusions, stress states, and spatial distributions. Then, based on the prefabricated notch parameters and the state of inclusions in the steel, a mathematical model of quantitative analysis is proposed, which can accurately predict the fatigue limit of heavy-duty gear steel. The research results can be applied to the actual use of heavy-duty gears and to the accurate life estimation based on the state of gear stress, thereby providing a quantitative reference model for subsequent gear steel production and gear part processing.

Analysis of Inclusion Microstructure in Material Engineering of Steel

2012 ◽  
Vol 568 ◽  
pp. 324-327
Author(s):  
Ding Guo Zhao ◽  
Shu Huan Wang ◽  
Ming Jian Guo
Keyword(s):  
Electron Microscopy ◽  
High Carbon Steel ◽  
Oxide Inclusion ◽  
Raw Material ◽  
High Carbon ◽  
Silicate Inclusion ◽  
Calcium Aluminates ◽  
Material Requirement ◽  
Lf Refining ◽  
Scanning Electron

The sample of oxide inclusion was obtained in the different stage of steelmaking for the 65 steel. The microstructure was observed by using scanning electron microscopy (SEM) to analyze the composition and type of inclusions. It was shown that the microscopic inclusions in the high carbon steel were mainly massive and cluster Al2O3, spherical and slope silicate inclusion, calcium-aluminates inclusions and sulphide complex inclusions. The measures including raw material requirement, improving of the converter, LF refining and continuous casting operations were put forward to decrease inclusion.

scholarly journals Pitting and Bending Fatigue Evaluations of a New Case-Carburized Gear Steel

2007 ◽  
Author(s):  
Timothy Krantz ◽  
Brian Tufts
Keyword(s):  
Power Density ◽  
Fatigue Testing ◽  
Surface Hardness ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Surface Fatigue ◽  
Gear Steel ◽  
Single Tooth ◽  
Carburized Gear ◽  
Gear Steels

The power density of a gearbox is an important consideration for many applications and is especially important for gearboxes used on aircraft. One approach to improving power density of gearing is to improve the steel properties by design of the alloy. The alloy tested in this work was designed to be case-carburized with surface hardness of Rockwell C66 after hardening. Test gear performance was evaluated using surface fatigue tests and single-tooth bending fatigue tests. The performance of gears made from the new alloy was compared to the performance of gears made from two alloys currently used for aviation gearing. The new alloy exhibited significantly better performance in surface fatigue testing, demonstrating the value of the improved properties in the case layer. However, the alloy exhibited lesser performance in single-tooth bending fatigue testing. The fracture toughness of the tested gears was insufficient for use in aircraft applications as judged by the behavior exhibited during the single tooth bending tests. This study quantified the performance of the new alloy and has provided guidance for the design and development of next generation gear steels.

scholarly journals Inclusion Characteristics in 95CrMo Steels with Different Calcium and Sulfur Contents

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 619 ◽  
Author(s):  
Xiang Li ◽  
Xiao Long ◽  
Linzhu Wang ◽  
Shouhao Tong ◽  
Xiutao Wang ◽  
...  
Keyword(s):  
Outer Layer ◽  
Three Dimensional ◽  
Average Diameter ◽  
Inclusion Size ◽  
Number Density ◽  
Cooling Process ◽  
Oxide Inclusions ◽  
Industrial Experiments ◽  
Size Number

In order to study the effect of Ca and sulfur contents on the characteristics of inclusions, industrial experiments using 95CrMo steel were conducted. SEM-EDS detections and stereological analysis were used to probe the characteristics of inclusions, including their compositions, morphologies, size, number density, and distribution. The results indicate that there were mainly three types of inclusions in 95CrMo steel billets with 6–18 ppm Ca and 30–100 ppm S: inclusions with single-phased morphology mainly composed of oxides; isolated MnS/CaS-only inclusions; inclusions with multi-phased morphology. The three-dimensional inclusion size distribution suggests that there were more Type-1 inclusions with a small size in low S containing steels. The average diameter of all types of inclusions increased with increasing Ca or S content in 95CrMo steel, indicating that the formation of MnS and CaS coarsened their size. The density distribution of inclusions indicates that the more inclusions there are, the more easily they aggregate and collide. Moreover, it is presumably concluded that the formation of sulfide in the outer layer of oxide inclusions weaken the attraction between oxide inclusions. The equilibrated transformation and formation of inclusions during the cooling process of 95CrMo steel was discussed based on thermodynamic calculation. The equilibrated transformation trajectory of inclusions in 95CrMo steel during the cooling process was Ca2SiO4 + MgO → Ca3MgSi2O8 → Spinel + CaS, which was corresponding to the detected results. The precipitation regular of sulfide was obtained. The formation mechanism for three types of inclusions was discussed.

Preparation and Formation Mechanisms of Monodispersed Mesoporous SiO2 Microspheres by the PICA Method

2007 ◽  
Vol 280-283 ◽  
pp. 1153-1156 ◽  
Author(s):  
Li Zhao ◽  
Jia Guo Yu ◽  
Rui Guo ◽  
Bei Cheng
Keyword(s):  
Silicon Dioxide ◽  
Pore Diameter ◽  
Average Diameter ◽  
Spherical Particles ◽  
Formation Mechanisms ◽  
Average Pore ◽  
Mesoporous Silicon ◽  
Surface Areas ◽  
Sio2 Microspheres ◽  
Scanning Electron

Monodispersed mesoporous silicon dioxide microspheres were prepared by polymerization-induced colloid aggregation (PICA) method and calcined at 850oC. The prepared samples were characterized with scanning electron microscopy (SEM), thermogravimetry (TG) and BET surface areas. The results showed that the obtained SiO2 microspheres had an average diameter of about 2.0 µm, a surface area of 253.3 m2g-1, an average pore volume of 0.62 mLg-1, and an average pore diameter of 7.9 nm. The formation mechanism of SiO2 spherical particles was discussed.

Effects of Oxide Inclusions on Texture of 1235 Al-Alloy after Deformation

2021 ◽  
Vol 1023 ◽  
pp. 53-59
Author(s):  
Wen Duan Yan ◽  
Gao Sheng Fu ◽  
Wan Qing Lai ◽  
Hong Ling Chen ◽  
Yan Li ◽  
...  
Keyword(s):  
Oxide Inclusion ◽  
Cube Texture ◽  
Deformation Texture ◽  
Al Alloy ◽  
Electron Backscattered Diffraction ◽  
Goss Texture ◽  
Oxide Inclusions ◽  
Relative Ratio ◽  
Deformation Properties ◽  
High Efficient

Texture characteristics of compressed 1235 Al-alloy treated by different purification methods are studied by electron backscattered diffraction. The effects of oxide inclusions on texture components of material are studied as well. The main textures in hot-compressed 1235 Al-alloy are Cube texture, R texture, Gross texture, Brass texture, and Rotated cube texture. The lower the content of oxide inclusions in the material, the smaller the total relative ratio of textures. The total relative ratio of textures goes to the smallest by 1.8 % in high-efficient purified 1235 Al-alloy by oxide inclusion content of 0.051 %. The purification results have obvious effects on types and percentage of texture in the deformed alloy. With the decreasing content of oxide inclusion, the ratio of deformation texture decreases and recrystallization texture increases. Brass texture is gradually replaced by Goss texture in the deformation textures. R texture is the main texture in recrystallization textures. Therefore, reducing the content of oxide inclusions is effective for improving the hot deformation properties of 1235 Al-alloy.

Study on Constitutive Model of 20CrMnTi Gear Steel in Cutting Process

2011 ◽  
Vol 291-294 ◽  
pp. 311-317 ◽  
Author(s):  
Gan Hua Liu ◽  
Hong Zhi Yan
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Metal Cutting ◽  
Cutting Process ◽  
Comprehensive Method ◽  
Model Flow ◽  
Gear Steel ◽  
Cutting Deformation ◽  
Flow Stress Data ◽  
Gear Steels

Flow stress data is important base data in using the analytical method and the finite element method to analyze the metal cutting process.In the present study, a comprehensive method combining with four methods of material mechanics tests, SHTB impact tests, two-dimensional orthogonal slot milling experiments and reverse solving is used to determine constitutive model (flow stress model) as a function of the "three-high" (high strain , temperature and strain rate) in metal cutting. The constitutive model of 20CrMnTi gear steel (hardened to170±5HB) which is one of China’s main gear steels in cutting deformation is established by using this method, and experimental results show that the model’s accuracy is high. Practice has proved that the methodology of constitutive model determination for metal cutting deformation, proposed in the present study, has advantages when compared with using one method alone, and is more suitable to establish flow data for the various materials in the metal cutting process.

scholarly journals Effect of Transformation Plasticity on Gear Distortion and Residual Stresses in Carburizing Quenching Simulation

Coatings ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1224
Author(s):  
Xusheng Li ◽  
Dongying Ju ◽  
Jianting Cao ◽  
Sirui Wang ◽  
Yong Chen ◽  
...  
Keyword(s):  
Phase Transformation ◽  
Residual Stresses ◽  
Numerical Simulations ◽  
Material Design ◽  
Physical Parameters ◽  
Transformation Plasticity ◽  
Helical Gears ◽  
Gear Steel ◽  
Design Software ◽  
Gear Steels

This paper addresses the effect of gear steel on distortion and residual stresses due to phase transformation in carburizing and quenching. In particular, the martensitic and bainitic phase transformation expansion and transformation plasticity properties of two automotive gearbox steels (20CrMnTiH and 20MnCr5) and their physical parameters are measured by experiments of transformation plasticity properties. Numerical simulations of the actual carburizing and quenching process of the gearbox spline helical gears were carried out in combination with the thermal and mechanical properties with temperature variations calculated by the material design software JMAT-Pro. In particular, the phase transformation properties of the two materials and their influence on the distortion and residual stresses after carburizing and quenching were verified by experiments of transformation plasticity and numerical simulations. A reliable basis is provided for predicting the distortion mechanism of gear steels in carburizing and quenching.

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