Guoxin Lu 卢国鑫

Shandong University | SDU · School of Material Science and Engineering

It is very challenging to prepare non-weldable Ni-based superalloys without defects by laser powder bed fusion (LPBF) technology since they are prone to cracking due to the comparatively high content of Al and Ti. This paper studied the reduction of the crack and porosity of a non-weldable superalloy, IN939 Ni-based alloy, by preheating substrate a...

Laser shock forming (LSF) is a novel plastic forming process which utilizes a laser-induced shock wave to deform metal sheet to 3D configurations. Quantitative evaluation of the deformation in LSF is of great importance to understand the forming mechanism and achieve the high precision. In this paper, an analytical model was proposed to predict the...

This study investigates the viability of employing a mechanical reshaping method to reduce the protrusion height of laser shock‐clinched joints while improving their strength. The method involves utilizing a pair of flat reshaping dies to compress the protrusion on laser shock‐clinched joints made of copper foils and stainless steel sheets. Through...

Residual stress is a ubiquitous phenomenon in laser powder bed fusion (LPBF) metal parts due to high temperature gradients and uneven heating during building processes. Subsequent stress-relief (SR) heat treatment is usually conducted to reduce the geometrical distortion and microscopic cracks induced by residual stress after the LPBF process. Usin...

Laser shock forming (LSF) is a novel plastic forming process which utilizes a laser-induced shock wave to deform sheet metals to 3D configurations. Quantitative evaluation of the deformation in LSF is of great importance to understand the forming mechanism and achieve the high precision. In this paper, considering parameters of material, geometry a...

The microscale laser shock clinching (LSC) is a promising micro-forming technology that enables the deformation-based joining of ultra-thin sheets. In this research, a numerical crystal plasticity model of the LSC process at ultra-high strain rates is established to incorporate the actual grain size of the material and the anisotropic characteristi...

As the hardware performance of laser and other infrastructures is restricted, how to effectively improve the intensity of the residual compressive stress field introduced by laser shocks has become the focus of researchers. With the help of the ABAQUS software of finite element simulation and the determined target material of 304-type steel, the ru...

The microscale laser shock clinching (LSC) is a promising micro-forming technology that enables the deformation-based joining of ultra-thin sheets. In this research, a numerical crystal plasticity model of the LSC process at ultra-high strain rates is established to incorporate the actual grain size of the material and the anisotropic characteristi...

Coated paperboard not only has the advantages of traditional paper such as low density and cleanliness, but also overcomes its disadvantages such as poor barrier performance and sensitivity to moisture. It is more and more widely used in forming packaging containers. The current research on mechanical performance and inelastic deformation of paperb...

The laser shock adhesive-clinching (LSAC) is an original material joining technique that combines the advantages of clinch-bonded hybrid joining and laser shock clinching, in which two metal foils are bonded by adhesive and clinched by laser shock simultaneously. In this paper, the LSAC joints are manufactured by 1060 Al foils, Henkel EP 5055 adhes...

In this paper, the β-tricalcium phosphate (β-TCP)/ZrO2 composite films were prepared at different laser fluences using pulsed laser deposition technology, and the effects of different ablation fluences on the morphology, structure, mechanical properties and in vitro biocompatibility of the films were investigated. The morphology and structure were...

This paper proposes an improved laser shock flat hole clinching process for joining ductile and brittle materials to obtain single-sided flat joints in microscale. A copper foil is clinched with a perforated sheet and a mechanical joining is achieved by this process. Experiments and numerical simulations are conducted for three thickness combinatio...

The effect of volume energy density and deposition energy density on the roughness, porosity, density and hardness of laser beam powder bed fusion (LBPBF) GTD222 Ni-based superalloy was systematically studied. The results showed that the roughness and porosity of the alloy decreased with the increase of the two laser energy densities, while the den...

Residual stress and distortion are inevitable during metal selective laser melting (SLM) process due to the high thermal gradient. Based on an experimental investigation and a numerical simulation, this paper studied the effect of geometric size and structural feature on the residual stress and distortion of hollow Ti-alloy blades fabricated using...

The appearance of the residual stress hole (RSH) phenomenon makes the otherwise perfect laser shock processing (LSP) method potentially defective. Residual compressive stress distribution appears in the areas irradiated by the laser beam while the central position of the laser beam pursues the residual tensile stress individually. This is prominent...

Zein/eug/TiO2 composite films were prepared by casting method at reaction temperature of 80℃ and drying temperature of 70℃. In order to investigate the influence of TiO2 nanoparticles on the performance and microstructure of zein/eug films, the surface and cross-section morphologies, functional groups, tensile properties, barrier properties, hydrop...

In this paper, an original process that making small-sized clinch-bonded hybrid joints by laser shock forming is put forward and developed, two metal foils, one adhesive layer and one perforated stainless steel sheet are joined together under continuous laser shocks. Finite element models are established to simulate the forming process and the shea...

A novel method to make a round end rectangular joint whose total length is much larger than the diameter of the laser spot, named as incremental laser shock clinching, was proposed in this paper. Experimental and numerical investigation was conducted to verify the feasibility for joining three sheets of copper/aluminum/stainless steel. The transver...

The difference between the physical principles of laser shock processing (LSP) and laser cavitation processing (LCP) is a scientific question that has long plagued researchers in different fields. This paper presents a controversial view on the formation of the laser force effect and maintains that the transformation of a pulsed laser into force en...

A three-dimensional finite-element model was generated of the hole expansion of a fit bushing for an aerospace aluminum alloy lug with a hole, and the effect of the compound hole expansion treatment in which the hole wall and the bushing are both extruded was investigated. Results show that the main technical advantage of compound hole expansion (C...

The “residual stress hole” destroys the uniformity of the residual stress distribution on the surface of laser shock-induced materials. Inhibiting the formation of the “residual stress hole” has significance for better exerting the surface modification effect of laser shock. This paper proposes the concept of the “energy blank zone”, which intends...

Residual stress in structural components is crucial as it affects both service performance and safety. To investigate the evolution of residual stress in a laser-peen-formed panel, this study adopted two plate samples of thickness 3 and 9 mm instead of the conventional Almen strip. The two plates were peened with an identical energy density of 10.9...

A metal material surface marking method was developed based on the theory that a larger thickness of the absorption layer can attenuate a laser-induced shock wave. The introduction of surface residual compressive stress is the main feature of this new marking method, which is different from the traditional mechanical processing marking method and i...

This paper summarises the regulation mechanism of the traditional and emerging surface strengthening treatments – mechanical shot peening (SP) and laser shock processing (LSP) treatment, respectively – on the fretting fatigue behaviour of the tenon joint materials of aero-engine cold-end parts, as surface strengthening treatment contributes to the...

We prepared samples with different surface roughnesses, which were subjected to laser shock treatment using the same laser parameters. We then investigated the effect of initial surface roughness on the actual intensity of laser shock. The results show that, after laser shock treatment, the lower the initial surface roughness of the target, the hig...

High-energy short-pulse lasers can induce significant shock waves, and they have been increasingly used in the field of material processing. The authors summarize the effects of pulsed laser-generated stresses on the surface topography of materials, introducing their related applications, and they highlight several unpredicted surface structures of...

The stress effect generated by a high-energy short-pulse laser is utilized to achieve performance enhancement or precise shaping of metal material components in laser shock technology. A method of marking metal materials using laser shock technology is introduced in this paper. The physical principle is the effect of thickness of absorbing layers o...

White light interference (WLI) data of different metal materials subjected to laser shock show two surface topography characteristics: laser shock-generated circle indentions with flat bottom or circular arc bottom. The difference of surface topographies is mainly related to the mechanical properties of metal materials. Hard metal materials acquire...

Laser shock treatment is a kind of advanced surface strengthening technology for metallic materials, and its remarkable strengthening effect has been verified and universally accepted in many different metallic materials. In order to prevent the influence of laser shock on the shape size of precision parts or make use of the technology to introduce...

Laser shock processing (LSP) can produce better strengthening effect than the traditional surface strengthening processes, and the induced microstructure change has higher thermal stability, which is expected to have a beneficial effect on the service performance of superalloy materials. The applications of LSP on different superalloy materials wer...

The formation of the residual stress field that accompanies severe plastic deformation is analyzed in view of the crystal structure evolution and mechanical response of the material. The conclusion drawn is that elastic release is the fundamental cause of the residual compressive stress field in the near-surface layer, while the residual tensile st...

Superalloys are required to withstand higher stresses and operating temperatures to meet the current demands for increased gas-turbine efficiency and superior damage tolerance. The challenges imposed on the service performance improvement not only relate to the bulk microstructure, but also to microstructures altered by post-processing technologies...

Isothermal fatigue testing was conducted on single crystal nickel-base superalloys. Distinct cracking behaviors were found to occur in the specimens treated by different laser shock processing (LSP) technologies. A crack generally initiates from the casting micropore. For the well surface strengthened specimens suffered high laser shock intensities...

The aim of the study was to investigate the effect of laser shock peening (LSP) on surface topography evolution of metallic targets. Samples manufactured by a Ni-based single crystal superalloy with polished finish were treated by LSP, and the surface topographies before and after LSP were examined by non-contact White-Light Interferometer (WLI). R...

The property of the surface layer of twice hole expansion Ti1023 alloy was analyzed by TEM, X-ray and roughness tester, and the strengthen mechanism of the bushing hole expansion was discussed. The results indicate that the roughness(Ra1.722→0.349 μm), hardness(Hv32→38) and residual stress distribution of the hole are improved by twice hole expansi...

Statistical analysis of white-light interferometry (WLI) experiments performed on Ni-based single-crystal superalloys (SX) have revealed a different height distribution between the dendritic cores (DCs) and the interdendritic regions (IRs) of the polished samples. The micromechanical property difference is largely ascribed to the uneven distributio...

A striking phenomenon is found that local plastic deformations, with an opposite direction to the external force, applied on metallic target surface under a given laser shock condition. Laser shock treatment is carried out on a number of metallic materials, and the surface topographies after laser shock treatment are observed via White Light Interf...

Superalloys are required to withstand higher stresses and operating temperatures to meet the current demands for increased gas-turbine efficiency and superior damage tolerance. Laser shock processing (LSP) is a newly established post-processing technology and it can introduce many beneficial effects refer to mechanical properties for metallic mater...

Surface topography and microhardness of a Ni-based single crystal superalloy subjected to laser shock peening (LSP) were investigated. So many morphological surface reliefs were found on the shocked surface, and a microscopic formation mechanism of those surface reliefs was proposed. The formation of surface reliefs can be attributed to the plastic...

300M steel was strengthened using two kinds of high intensity shot peening process in different intensities of 0.424 mm and 0.576 mm, the strengthening effects were investigated through surface integrity, residual stress field, microhardness and fatigue resistance. Results show that the shot peening surface of 300M steel was completely covered by c...

为进一步优化孔挤压工艺效果,利用有限元软件Abaqus6.12对300M钢孔挤压工艺的三维模型进行了数值模拟,重点研究芯棒规格对孔挤压强化效果的影响。模拟结果表明芯棒形状与尺寸对孔挤压效果有明显影响:过盈部位位于芯棒后通过部分时,孔壁获得一定深度的残余压应力场且轴向塑性形变量最小,强化效果最优;过盈部位位于芯棒后通过部分,过盈部位长度不同的各工艺中,过盈部位长度最大时获得最优强化效果;适当增大芯棒出口直径,可提高强化效果。过盈部位位置、过盈部位长度、入/出口锥度、芯棒出口直径等表征芯棒规格的参数均会对孔挤压强化效果造成一定影响。

A new idea was proposed in the present work, based on the principle for the balance of stress field strength, to judge qualitatively the surface residual stress trends, and it was verified by the experimental results in literatures. For the surface-strengthened sample with a surface residual compressive stress field, the proposed theory shows that,...

Residual stress and microhardness in a certain depth from the surface were measured to obtain the strain characteristics of 300M steel after surface strengthening treatment. As the only way to indicate the strain hardening characteristics, the surface-matrix microhardness variation trends of shot peening specimens shows strain hardening characteris...

Further research was performed to find out the causes of fatigue fracture from the perspective of hole wall strength change under tensile load; test data were analyzed based on the tested microhardness and residual stress, combined with the finite element simulation result. The analysis results show that the fatigue fracture samples present microha...

Few reports are currently available about the numerical simulation analysis of shot peening effectiveness involving both shot peening pressure and pill diameter. Therefore, the shot peening strengthening process of 300M stainless steel was numerically simulated with finite element software ABAQUS/Explicit. The shot peening of the steel was conducte...

The model of 300M steel shot-peening process is built using finite element analysis software ABAQUS 6.12. The cycle plastic deformation of the target material is simulated by the way of several attacks on targets with one shot. Three shot-peening processes with the same kinetic energy input are selected to compare the residual stress field after sh...