The Experts below are selected from a list of 18654 Experts worldwide ranked by ideXlab platform
Wen He - One of the best experts on this subject based on the ideXlab platform.
-
influence of different laser re melting paths on the microstructure of a spray coating defect prevention and tribological properties
Surface & Coatings Technology, 2019Co-Authors: Yuncai Zhao, Xuehua Wu, Huihui Du, Xuchao Shangguan, Wen HeAbstract:Abstract The laser re-melting process parameters exerted a significant effect on the improvement of microstructure defects and tribological properties of the coatings. In this paper, four different laser re-melting trajectories coating, including dot, rectangle, parallel, and circular, were provided on the Fe based Ni/WC ceramet composite coating by flame spraying. The effects of different laser Remelting trajectories on the microstructure defects and tribological properties of the coatings were discussed. The results showed that the formation and development of pores and cracks could be effectively inhibited by the circular Remelting trajectory. Due to the original holes and cracks existed in the flame-sprayed coating, the inhibitory effect on microstructural defects of dot re-melting coating was not satisfactory. Under the circular re-melting trajectory, the microstructure of the remelted layer was fine equiaxed crystal, and no preferred orientation or fragile interface existed in the coatings. Besides, the strengthening mechanism of the coating after laser Remelting changed from the original deformation strengthening to second phase strengthening, fine grain strengthening and solid solution strengthening. The W2C and other hard phases distributed in the re-melted coatings and played a role of dispersion strengthening. The wear loss of the coating under circular Remelting trajectory was 30.2% of that under spot Remelting trajectory. The higher hardness, lower friction coefficient, and more precipitation of the hard phases were found in the Remelting coatings under circular Remelting trajectory and parallel Remelting trajectory than that under other two trajectories (Figs. 6, 7, 8), which meant these two trajectories were the ideal Remelting coating track.
Janez Grum - One of the best experts on this subject based on the ideXlab platform.
-
Influence of Laser Surface Remelting on Al-Si Alloy Properties
Strojniski Vestnik-journal of Mechanical Engineering, 2012Co-Authors: Janez Sušnik, Roman Šturm, Janez GrumAbstract:The paper treats hardenable Al-Si alloy after laser surface Remelting by the changes in microstructure and micro-hardness of a modified surface layer. Laser Remelting of the thin surface layer was carried out with different energy inputs into the as-cast specimen surface. The Remelting conditions were varied by application of different laser beam pulse duration. After solidification of surface remelted layer a fine-grained microstructure is formed. Such a microstructure increases micro-hardness of hardenable Al-Si alloy for about 60-80%. The variation and size of mainly tensile residual stresses in surface remelted layer greatly depends on the cooling rates i.e. laser pulse duration. Precipitation annealing after the process of laser surface Remelting additionally influences on reduction of residual stresses.
-
effect of laser Remelting of surface cracks on microstructure and residual stresses in 12ni maraging steel
Applied Surface Science, 2006Co-Authors: Janez Grum, Janez Marko SlabeAbstract:The paper presents the results of a study on possible application of laser-Remelting to repair of narrow and comparatively deep cracks at the surface of highly thermo-mechanically loaded parts made of 12% Ni hot-working maraging tool steel. Laser-Remelting of maraging steel is, due to very good weldability and flexibility of the process, very prospective for repair of fatigued surfaces of parts made of this steel at which the presence of surface microcracks may be observed. In addition to the efficiency of crack Remelting, the influence of laser-Remelting on the heat-affected zone in terms of its microstructure and residual stresses was also studied. The microstructure in the laser-remelted track is cellular/dendritic. In the heat-affected zone surrounding the laser-remelted track, the microstructure varies considerably. A microstructure analysis revealed, in the heat-affected zone, five microstructural zones and sub-zones. Residual stresses measured after laser-Remelting are with reference to gradual through-depth changing of the stresses favourable.
-
Deformation of specimen during laser surface Remelting
Journal of Materials Engineering and Performance, 2000Co-Authors: Janez Grum, Roman ŠturmAbstract:During laser surface Remelting, thermal expansion in heating, and contraction of material in cooling, and due to microstructure changes in the heated surface layer, the specimen deforms. This induces volume changes during the process of Remelting the thin surface layer and causes internal stresses. By measuring the deformation of the specimen during the Remelting process as well as after the laser beam interaction, i.e. , to the moment when the specimen cools down to the ambient temperature, it is possible to follow the progress of deformation in the specimen material. Detailed information on the deformation events in the specimen material during the laser Remelting process of a thin surface layer enables the engineer to optimize the process variables in terms of amount of deformation or magnitude of residual stresses on completion of cooling.
Andrzej Wojciechowski - One of the best experts on this subject based on the ideXlab platform.
-
Wear Resistance of Aluminum Matrix Composites Reinforced with Al_2O_3 Particles After Multiple Remelting
Journal of Materials Engineering and Performance, 2016Co-Authors: Adam Klasik, Krystyna Pietrzak, Katarzyna Makowska, Jerzy Sobczak, Dariusz Rudnik, Andrzej WojciechowskiAbstract:Based on previous results, the commercial composites of A359 (AlSi9Mg) alloy reinforced with 22 vol.% Al_2O_3 particles were submitted to multiple Remelting by means of gravity casting and squeeze-casting procedures. The studies were focused on tribological tests, x-ray phase analyses, and microstructural examinations. More promising results were obtained for squeeze-casting method mainly because of the reduction of the negative microstructural effects such as shrinkage porosity or other microstructural defects and discontinuities. The results showed that direct Remelting may be treated as economically well-founded and alternative way compared to other recycling processes. It was underlined that the multiple Remelting method must be analyzed for any material separately.
-
wear resistance of aluminum matrix composites reinforced with al2o3 particles after multiple Remelting
Journal of Materials Engineering and Performance, 2016Co-Authors: Adam Klasik, Krystyna Pietrzak, Katarzyna Makowska, Jerzy Sobczak, Dariusz Rudnik, Andrzej WojciechowskiAbstract:Based on previous results, the commercial composites of A359 (AlSi9Mg) alloy reinforced with 22 vol.% Al2O3 particles were submitted to multiple Remelting by means of gravity casting and squeeze-casting procedures. The studies were focused on tribological tests, x-ray phase analyses, and microstructural examinations. More promising results were obtained for squeeze-casting method mainly because of the reduction of the negative microstructural effects such as shrinkage porosity or other microstructural defects and discontinuities. The results showed that direct Remelting may be treated as economically well-founded and alternative way compared to other recycling processes. It was underlined that the multiple Remelting method must be analyzed for any material separately.
Yuncai Zhao - One of the best experts on this subject based on the ideXlab platform.
-
influence of different laser re melting paths on the microstructure of a spray coating defect prevention and tribological properties
Surface & Coatings Technology, 2019Co-Authors: Yuncai Zhao, Xuehua Wu, Huihui Du, Xuchao Shangguan, Wen HeAbstract:Abstract The laser re-melting process parameters exerted a significant effect on the improvement of microstructure defects and tribological properties of the coatings. In this paper, four different laser re-melting trajectories coating, including dot, rectangle, parallel, and circular, were provided on the Fe based Ni/WC ceramet composite coating by flame spraying. The effects of different laser Remelting trajectories on the microstructure defects and tribological properties of the coatings were discussed. The results showed that the formation and development of pores and cracks could be effectively inhibited by the circular Remelting trajectory. Due to the original holes and cracks existed in the flame-sprayed coating, the inhibitory effect on microstructural defects of dot re-melting coating was not satisfactory. Under the circular re-melting trajectory, the microstructure of the remelted layer was fine equiaxed crystal, and no preferred orientation or fragile interface existed in the coatings. Besides, the strengthening mechanism of the coating after laser Remelting changed from the original deformation strengthening to second phase strengthening, fine grain strengthening and solid solution strengthening. The W2C and other hard phases distributed in the re-melted coatings and played a role of dispersion strengthening. The wear loss of the coating under circular Remelting trajectory was 30.2% of that under spot Remelting trajectory. The higher hardness, lower friction coefficient, and more precipitation of the hard phases were found in the Remelting coatings under circular Remelting trajectory and parallel Remelting trajectory than that under other two trajectories (Figs. 6, 7, 8), which meant these two trajectories were the ideal Remelting coating track.
Adam Klasik - One of the best experts on this subject based on the ideXlab platform.
-
Wear Resistance of Aluminum Matrix Composites Reinforced with Al_2O_3 Particles After Multiple Remelting
Journal of Materials Engineering and Performance, 2016Co-Authors: Adam Klasik, Krystyna Pietrzak, Katarzyna Makowska, Jerzy Sobczak, Dariusz Rudnik, Andrzej WojciechowskiAbstract:Based on previous results, the commercial composites of A359 (AlSi9Mg) alloy reinforced with 22 vol.% Al_2O_3 particles were submitted to multiple Remelting by means of gravity casting and squeeze-casting procedures. The studies were focused on tribological tests, x-ray phase analyses, and microstructural examinations. More promising results were obtained for squeeze-casting method mainly because of the reduction of the negative microstructural effects such as shrinkage porosity or other microstructural defects and discontinuities. The results showed that direct Remelting may be treated as economically well-founded and alternative way compared to other recycling processes. It was underlined that the multiple Remelting method must be analyzed for any material separately.
-
wear resistance of aluminum matrix composites reinforced with al2o3 particles after multiple Remelting
Journal of Materials Engineering and Performance, 2016Co-Authors: Adam Klasik, Krystyna Pietrzak, Katarzyna Makowska, Jerzy Sobczak, Dariusz Rudnik, Andrzej WojciechowskiAbstract:Based on previous results, the commercial composites of A359 (AlSi9Mg) alloy reinforced with 22 vol.% Al2O3 particles were submitted to multiple Remelting by means of gravity casting and squeeze-casting procedures. The studies were focused on tribological tests, x-ray phase analyses, and microstructural examinations. More promising results were obtained for squeeze-casting method mainly because of the reduction of the negative microstructural effects such as shrinkage porosity or other microstructural defects and discontinuities. The results showed that direct Remelting may be treated as economically well-founded and alternative way compared to other recycling processes. It was underlined that the multiple Remelting method must be analyzed for any material separately.
