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Your search keyword '"Zhibing, Liu"' showing total 4 results
Start Over Author "Zhibing, Liu" Topic surface integrity
4 results on '"Zhibing, Liu"'

1. A plastic strain energy method exploration between machined surface integrity evolution and torsion fatigue behaviour of low alloy steel

Author

Ci Song, Yifan Bai, Wang Yong, Liu Yang, Hongtao Chen, Xibin Wang, Pai Wang, Liu Shuyao, Zhibing Liu, and Sitao Wang

Subjects
Materials science, Carbon steel, Mechanical Engineering, Aerospace Engineering, Strain energy density function, engineering.material, Strain energy, Machining, Residual stress, engineering, Surface roughness, Process optimization, Composite material, Surface integrity
Abstract

To explore the evolution mechanism of multistage machining processes and torsional fatigue behaviour based on strain energy for the first time and provide process optimization of axis parts of low-alloy medium-carbon steel for service performance, four multistage machining processes were applied to the 45CrNiMoVA steel, including the rough turning process (RT), RT + the finish turning process (FRT), FRT+ the grinding process (GFRT) and RT+ the finish turning process on dry cutting condition (FRT0). The result showed that the FRT process’s average low-cycle torsional fatigue life increased by 50% when it evolved from the RT process. The lower surface roughness of Ra 1.3 μm caused the total strain energy to increase by 163.8 Pa mm/mm instead of the unchanged strain energy density, and the crack feature evolved from some specific bulges to flat shear plane characteristics. When the GFRT process evolved from the FRT process, its average fatigue life increased by 1.45 times, compared with the RT process. Plastic strain amplitude decreased by 21%, and the strain energy density decreased by 4% due to more considerable compressive residual stress (-249 MPa). Plastic deformation layer depth had a consistent tendency with surface roughness. In this paper, surface integrity evolutions on cyclic characteristics and fatigue behaviour have also been explained. A fatigue life prediction model based on the energy method for machined surface integrity is proposed.

Published
2022

2. Influence of laser shock peening on surface integrity and tensile property of high strength low alloy steel

Author

Liu Shuyao, Zhibing Liu, Puyi Wang, Xibin Wang, Wenjuan Wan, Wang Yong, and Xiaoyu Pan

Subjects
Yield characteristic, 0209 industrial biotechnology, Materials science, Yield (engineering), Scanning electron microscope, Residual stress, Aerospace Engineering, 02 engineering and technology, engineering.material, 01 natural sciences, 010305 fluids & plasmas, 020901 industrial engineering & automation, 0103 physical sciences, Ultimate tensile strength, parasitic diseases, Laser shock peening, Composite material, Motor vehicles. Aeronautics. Astronautics, High-strength low-alloy steel, Mechanical Engineering, fungi, Peening, Tensile property, TL1-4050, Shock (mechanics), engineering, 32CrNi steel, Surface integrity
Abstract

Laser Shock Peening (LSP) is a well-established surface treatment commonly used to improve mechanical properties of material's surfaces. To further understand the relationship between tensile property and fatigue life improvement of high strength low alloy steel in the LSP process, LSP treatment of 32CrNi high strength low alloy steel was carried out by YAG laser with pulse energy of 15 J, and tensile property was tested by electronic universal material testing machine. Surface morphology, residual stress and tensile fracture of the specimens before and after LSP were observed by white light interferometer (WLI), X-ray measuring apparatus and scanning electron microscope (SEM). Result shows that LSP did not change tensile strength of 32CrNi steel but cause yield characteristic transform from obvious yield point to no yield phenomenon which is the only factor benefiting fatigue life, indicating that the increment of fatigue life was probably related to the disappearance of yield phenomenon. Formation mechanisms of tensile fractures and yield phenomenon induced by LSP at room temperature were also discussed and completely revealed. Deeper compressive residual stress and flat grains contributed to the transition of yield characteristic and lower elongation rate of 32CrNi steel subjected to LSP.

Published
2021

3. Effect of machining processes on the quenching and tempering surface layer of ultra-high strength steel.

Author

Yong, Wang, Xibin, Wang, Zhibing, Liu, Shuyao, Liu, Mingming, Ren, Zhibin, Wang, Xiaofeng, Qin, Feng, Li, Fengbin, Liu, Zuomei, Yang, Jiayi, Ren, Weidong, Shen, Hongtao, Chen, and WangPai

Subjects
*TEMPERING, *MACHINING, *ELECTRIC machines, *RESIDUAL stresses, *STEEL
Abstract

The initial characteristics of the surface layer following the quenching and tempering treatment of ultra-high-strength steel play a significant role in determining the subsequent precision machining. This study focus on investigating the influence of machining processes on the quenching and tempering surface layer. The machining processes affect both the oxidation of the quenching and tempering treatment and the development of a distinct preferred grain orientation. Gradual diminishment of surface abrasions leads to the transformation of the needle-like oxidation pattern into a layered oxidation structure. The preferred orientation of the grains prevents the grains from shear sliding, thereby enhancing the Taylor effect. Formation mechanisms of the microhardness and residual stress of the quenching and tempering surface layer induced by machining processes were also discussed and completely revealed. The microhardness is mainly attributed to the dynamic Hall-Petch effect, while plastic strain, dislocation energy storage, and phase transformation contribute to the residual stress changes. • Formation mechanisms of the quenching and tempering surface layer induced by machining processes were revealed. • Machined surface morphology affects preferred grain orientation preference and austenitization characteristics. • Microhardness of the surface layer induced by machining processes is mainly attributed to the dynamic Hall-Petch effect. [ABSTRACT FROM AUTHOR]

Published
2023
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4. Effects of laser shock peening in different processes on fatigue life of 32CrNi steel.

Author

Yong, Wang, Xibin, Wang, Zhibing, Liu, Shuyao, Liu, Hui, Chen, Xiaoyu, Pan, and Hongtao, Chen

Subjects
*LASER peening, *STEEL fatigue, *FATIGUE life, *HIGH strength steel, *HIGH cycle fatigue, *RESIDUAL stresses, *SURFACE roughness, *COATING processes
Abstract

To further understand the effects of LSP on large components of high strength steel and provide improved solutions, this paper conducts research on effects of surface integrity on fatigue life in the LSP process with absorbent coating (LSPC), without absorbent coating (LSPN), without absorbent coating but with axial polishing (LSPP) respectively. The research also put a baseline specimens (BSL) before LSP for a comparison. Results show that average fatigue life in the LSPN process is 47.8% shorter than that of baseline specimens, and crack site area presents an obvious splitting-like tearing step. In the LSPC process, fatigue life is 31.7% longer than that of baseline specimens, and crack initiation site develops from surface to subsurface. In the LSPP process, the specimens show the longest fatigue life of 2.53 × 105cycles, with multiple fine microcracks developing simultaneously. Axial polishing removes ablative layer and tensile residual stress in the LSPN process and reduces dislocation pile-ups and refines grains in the LSPC process, resulting in a surface roughness of R a 0.61 μm, surface residual stress of −531MPa and microhardness of 405HV 0.025.Thus, the fatigue performances were found to be significantly affected by multiple surface integrity indicators induced by different LSP processes. In this paper, the effect of LSP on surface integrity on the subface and its influence on crack initiation and propagation have also been discussed, the crack initiation mechanisms in different processes were explained by using Murakami's K max equation. [ABSTRACT FROM AUTHOR]

Published
2020
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