Jin Zhon Lu

Bio: Jin Zhon Lu is an academic researcher from Jiangsu University. The author has contributed to research in topics: Residual stress & Peening. The author has an hindex of 2, co-authored 10 publications receiving 291 citations.

Study on Mechanism and Experiment of Engine Cylinder by Laser Honing

Abstract: The diesel engine cylinder was processed by laser honing (LH) device, the structure morphology was observed with scanning electric mirror (SEM), and lubricant consumes and wear performances were measured, at the same time the mechanism of LH and effects of laser parameters on LH results were analyzed. The experimental results are shown that LH is a kind of phase transformation treatment by laser, which processes a hardening belt in the certain distributing form on the work-piece surface, and forms the hardness distribution of soft and hard material alternatively; LH may lower the engine oil consumes 30%-60%, and reduce the pollution of the catalyst machine, and lower the grain let of the engine oil 25%-30%. LH intentionally machines the grain cave, which has the certain angle, depth, and width etc.. The surface microcosmic sculpting has the lubricating function for usage process, and storage and transport lubricant, which improves the rubbing condition, then lower the part wear and increase the other performances. The short-wave laser is more applicable to the LH process, which improves the lubrication condition, and increases the service life of the engine and the efficiency, and lowers the engine oil consumes.

Study on the Testing Technology of Main Residual Stress of Metal Sheet Based on Soft X-Ray Diffraction Stress Analyzer

Abstract: For the characteristics of soft X-ray stress testing technology, a formula to resolve main residual stress is deduced based on analyzing the relationship between main residual stress and normal stress of different sections. The distribution of main stress of laser shock forming TA2 metal sheet is studied combined with the experimental study on the determining residual stress with soft X ray diffraction analyzer. The result shows that testing and calculating main residual stress is an important approach to study the deformation law of sheet metal material.

Investigation on Performance of QT700-2 Material by Laser Peening

Abstract: With the advent of high-power pulsed lasers, laser peening has emerged as a new and very promising technique to improve the resistance properties of materials to fatigue, wear and corrosion. In this paper, the effect of laser peening on the surface performance of QT700-2 materials was investigated, the parameters of laser peening were optimized by an artificial neural network (ANN) method. A series of experiments was carried out by using a high-power, Q-Switched, pulsed neodymium-glass laser. The microstructure features were analyzed with SEM and the hardness and residual stresses at the surface and in-depth were measured. The results indicate that the depth of hardened layer was about 0.31i1.40mm for a different shot number of 1-4 times and the compressive residual stress at the surface increases with increasing laser pulse energy, from -165MPa for the low energy 12J to -410MPa for the higher energy 20J. Laser peening can restrain nucleation of fatigue cracks and improve the fatigue life of nodular cast iron materials.

Effect of Strain-Rate on the Fracture Morphology of LY2 Aluminum Alloy by Laser Shock Processing

Abstract: The strain-rate sensitivity of LY2 aluminum (Al) alloy subjected to laser shock processing (LSP) was investigated according to the fracture morphology at strain-rates ranging from 0.00001 s-1 to 0.1 s-1. The fracture morphology was observed by the scanning electron microscopy (SEM). Fracture morphology at different strain-rates suggested that LY2 Al alloy after LSP seemed to evolve towards a more ductile dimple fracture mode with increasing the strain-rates. The relations underlying the fracture morphology and strain-rate sensitivity were also addressed.

Gradient nanostructure and residual stresses induced by Ultrasonic Nano-crystal Surface Modification in 304 austenitic stainless steel for high strength and high ductility

Abstract: In this study, the effects of Ultrasonic Nano-crystal Surface Modification (UNSM) on residual stresses, microstructure changes and mechanical properties of austenitic stainless steel 304 were investigated. The dynamic impacts induced by UNSM leads to surface nanocrystallization, martensite formation, and the generation of high magnitude of surface compressive residual stresses (−1400 MPa) and hardening. Highly dense deformation twins were generated in material subsurface to a depth of 100 µm. These deformation twins significantly improve material work-hardening capacity by acting both as dislocation blockers and dislocation emission sources. Furthermore, the gradually changing martensite volume fraction ensures strong interfacial strength between the ductile interior and the two nanocrystalline surface layers and thus prevents early necking. The microstructure with two strong surface layers and a compliant interior embedded with dense nanoscale deformation twins and dislocations leads to both high strength and high ductility. The work-hardened surface layers (3.5 times the original hardness) and high magnitude of compressive residual stresses lead to significant improvement in fatigue performance; the fatigue endurance limit was increased by 100 MPa. The results have demonstrated that UNSM is a powerful surface engineering technique that can improve component mechanical properties and performance.

Microstructure modelling for metallic additive manufacturing: a review

Abstract: The microstructure of metals depends on the additive manufacturing (AM) process and the process parameters. However, experimentation on different process parameters for different materials is costl...