Yuan Ren

Bio: Yuan Ren is an academic researcher from Xi'an Jiaotong University. The author has contributed to research in topics: Ultimate tensile strength & Microstructure. The author has an hindex of 1, co-authored 4 publications receiving 45 citations.

Recent research and development status of laser cladding: A review

Abstract: In industries such as aerospace, petrochemistry and automobile, many parts of different machines are under environment which shows high temperature and high pressure, and have their proneness to wear and corrosion. Therefore, the wear resistibility and stability under high temperature need to be further improved. Nowadays, Laser cladding (LC) is widely used in machine parts repairing and functional coating due to its advantages such as lower dilution rate, small heat-affected zone and good metallurgical bonding between coating and substrate. In this paper, LC is introduced in detail from aspects of process simulation, monitoring and parameter optimization. At the same time, the paper gives a comprehensive review over LC material system as high entropy alloys (HEAs), amorphous alloy and single crystal alloy have been gradually showing their advantages over traditional metal materials in LC. In addition, the applications of LC in functional coatings and in maintenance of machine parts are also outlined. Also, the existing problems and the development trend of LC is discussed then.

CrCoNi medium-entropy alloy thin-walled parts manufactured by laser metal deposition: Microstructure evolution and mechanical anisotropy

Abstract: Laser metal deposition (LMD) shows outstanding advantages in manufacturing complex parts. In practice, some formed parts usually require directional properties in order to obtain better service performance in its use. This study has comprehensively analyzed the microstructure, texture and porosity of CrCoNi medium-entropy alloy thin-walled parts manufactured by LMD process, as well as the effect of these factors on its mechanical anisotropy. The results show that the yield strength in the building direction is slightly higher than the scanning direction and the uniform elongation is about 1.5 times. Meanwhile, the fracture morphology and microcrack characteristics of the tensile samples in these two directions have also been studied. The results reveal that cross-slip microcracks and microcrack deflection appeared in the scanning direction and building direction, respectively. In addition, it has also been made clear that initial dislocations can contribute to the yield strength of thin-walled samples. The work provides guidance for the design freedom and scanning strategy of engineering parts with directional performance by the LMD process.

Research on process optimization and microstructure of CrCoNi medium-entropy alloy formed by laser metal deposition

Abstract: Laser metal deposition (LMD) has shown its unique advantages in surface strengthening coatings and parts repair, and has brought revolutionary changes to manufacturing industry. However, unexpected shaping and internal defects can occur when an inappropriate combination of process parameters are used in the LMD process. These problems need to be solved to ensure satisfactory printed parts when using LMD. This study uses response surface methodology and multi-objective gray wolf optimization algorithm to obtain the process parameters of a single track with excellent forming quality. The results show that the process parameters have an important impact on the forming quality, and a single track with a good shape and microstructure are formed when the obtained optimal process parameters be used. In addition, the effects of laser energy densities on the microstructure and microhardness of printed parts were also studied by contrast experiments. The results indicate that the microstructure of the printed parts changes and the sub-grain size decreases with the decrease of the laser energy density, which ultimately leads to an increase in its microhardness. This work provides guidance for the selection of process parameters for surface enhancement coatings and parts repair by the LMD process.

Effect of laser incident energy on the densification and structure–property relationships of additively manufactured CrCoNi medium-entropy alloy

Abstract: Directed energy deposition (DED) shows outstanding advantages in manufacturing complex and functionally graded parts. This study systematically investigated the effect of laser incident energy on t...

Wear mechanisms and micro-evaluation on WC particles investigation of WC-Fe composite coatings fabricated by laser cladding

Abstract: With WC as the reinforcing phase particles, the Fe-WC composite coatings with mass fractions 0–60 wt% of WC were fabricated on a 15CrNiMo cone bit steel by laser cladding The phase composition, microstructure, microhardness, friction and wear properties of the composite coatings were studied Moreover, special attention was paid to investigate the thermal damage forms of WC particles and its influence mechanism on the structure evolution and wear properties The research results reveal that most of the WC particles maintain their complete morphology, but some WC particles are melted due to the thermal damage type of dissolution-collapse-precipitation The degree of burning loss rate is related to the quantity distribution and average particle size of WC in local area Main surrounding structures of WC are composed of equiaxed and cellular crystals, and few short columnar crystals The microhardness of the WC-Fe composite coating increases with increasing WC particles content Compared with the microhardness (6217HV02) of the Fe-based coating, the microhardness of the WC-Fe composite coating gradually increased from 7299HV02 to 10292HV02, and its average relative wear resistance is 13 times that of the coating without WC particles Moreover, combined with existing WC and W2C, as well as the presence of precipitated M23C6, M7C3 and η phases, which significantly improve the wear resistance of WC-Fe composite coatings In summary, the main wear mechanisms of Fe-based coatings reinforced by WC particles are abrasive wear accompanied by varying degrees of adhesive wear and three-body abrasive wear

Laser deposition of high-entropy alloys: A comprehensive review

Abstract: Since the advent in 2004, high-entropy alloys (HEAs) have become an attraction for the world and applied in the extensive engineering fields due to their outstanding properties. These materials are exhibiting their potentiality for challenging conditions where coatings are applied through laser deposition technology. Laser deposition techniques containing laser cladding (LC), laser surface alloying (LSA), and laser surface remelting (LSR) are the modern technologies that can be applied for surface modification through HEAs. Nobler properties of the LC-HEA depositions over the conventional alloys have further explored this field in the last few years. Here, this paper provides a comprehensive state-of-the-art review for LC-HEA-based coatings, focusing on the use of laser deposition technique for HEAs, the effect of laser process parameters on mechanical properties, and microstructural evolution. The mechanical characteristics include but are not limited to hardness, wear, corrosion, and erosion resistance are discussed, with regard to their microstructure and phase composition. Besides, the existing problems, possible future developments regarding the LC-HEA depositions are predicted. Due to excellent mechanical properties and functional potential as well as a variety of element constitutions for HEA designing, laser-assisted depositions containing blended HEAs as feedstock material will have promising applications prospects in the field of material science and engineering.

Laser deposition of high-entropy alloys: A comprehensive review

Abstract: Since the advent in 2004, high-entropy alloys (HEAs) have become an attraction for the world and applied in the extensive engineering fields due to their outstanding properties. These materials are exhibiting their potentiality for challenging conditions where coatings are applied through laser deposition technology. Laser deposition techniques containing laser cladding (LC), laser surface alloying (LSA), and laser surface remelting (LSR) are the modern technologies that can be applied for surface modification through HEAs. Nobler properties of the LC-HEA depositions over the conventional alloys have further explored this field in the last few years. Here, this paper provides a comprehensive state-of-the-art review for LC-HEA-based coatings, focusing on the use of laser deposition technique for HEAs, the effect of laser process parameters on mechanical properties, and microstructural evolution. The mechanical characteristics include but are not limited to hardness, wear, corrosion, and erosion resistance are discussed, with regard to their microstructure and phase composition. Besides, the existing problems, possible future developments regarding the LC-HEA depositions are predicted. Due to excellent mechanical properties and functional potential as well as a variety of element constitutions for HEA designing, laser-assisted depositions containing blended HEAs as feedstock material will have promising applications prospects in the field of material science and engineering.