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14 pages, 8809 KiB

Open AccessArticle

Wear Behavior of Medium-Carbon Steel with Different Laser-Textured Densities under Starved Lubrication

by Fanming Zeng, Yuting Liu, Feixian Shao, Xiujuan Li, Zhenglei Yu, Yunting Guo, Zhenping Wan, Longsheng Lu and Zhihui Zhang

Coatings 2020, 10(12), 1225; https://doi.org/10.3390/coatings10121225 - 15 Dec 2020

Cited by 2 | Viewed by 2285

Abstract

Five densities of laser-ablated micro-pits were fabricated onto medium-carbon steel surfaces based on the coupling effect of the biological surface. The effects of the surface textures on the wear behavior were investigated by sliding wear tests under starved lubrication. The results show that compared with the smooth sample, the biomimetic samples could effectively reduce friction and wear, and the tribological performance of the textured surfaces is closely related to the density of the bionic units. The equivalent stress distribution of the specimens was simulated by the finite element method. A uniform stress distribution is beneficial for effectively reducing the generation of wear cracks. Full article

(This article belongs to the Section Corrosion, Wear and Erosion)

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18 pages, 8170 KiB

Open AccessArticle

Effects of Laser Melting Distribution on Wear Resistance and Fatigue Resistance of Gray Cast Iron

by Haiyang Yang, Ti Zhou, Qingnian Wang and Hong Zhou

Metals 2020, 10(9), 1257; https://doi.org/10.3390/met10091257 - 17 Sep 2020

Cited by 9 | Viewed by 2755

Abstract

The coupling bionic surface is generally prepared by laser melting on the surface of a gray iron brake hub, which can allow the brake hub to achieve excellent wear resistance and fatigue resistance. The designs of most previous experiments have been based on independent units that were uniform in their distribution patterns. Although some progress has been made in the optimization of cell features, there is still room for further improvement with respect to bionics and experimental optimization methods. Here, experiments on units with non-uniform distributions of different distances were used to rearrange and combine the bionic elements. This paper is that the original uniform distribution laser melting strengthening model was designed as a non-uniform distribution model, and the heat preservation and tempering strengthening effect of continuous multiple melting strengthening on the microstructure of the melting zone is discussed. The mechanism of crack initiation and the mode of crack propagation were analyzed. The relationship between the internal stress in the melting zone and the crack initiation resistance was also discussed. In this paper, the mechanism of different spacing distribution on the surface of gray cast iron by laser remelting is put forward innovatively and verified by experiments, which provides a solid theoretical basis for the follow-up industrial application. Full article

(This article belongs to the Special Issue Advances in Laser Materials Processing)

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15 pages, 8110 KiB

Open AccessArticle

Bionic Repair of Thermal Fatigue Cracks in Ductile Iron by Laser Melting with Different Laser Parameters

by Siyuan Ma, Ti Zhou, Hong Zhou, Geng Chang, Benfeng Zhi and Siyang Wang

Metals 2020, 10(1), 101; https://doi.org/10.3390/met10010101 - 9 Jan 2020

Cited by 18 | Viewed by 3728

Abstract

Nodular iron brake discs typically fail due to serious thermal fatigue cracking, and the presence of graphite complicates the repair of crack defects in ductile iron. This study presents a novel method for remanufacturing ductile iron brake discs based on coupled bionics to repair thermal fatigue cracks discontinuously using bio-inspired crack blocking units fabricated by laser remelting at various laser energy inputs. Then, the ultimate tensile force and thermal fatigue crack resistance of the obtained units were tested. The microhardness, microstructure, and phases of the units were characterized using a digital microhardness meter, optical microscopy, scanning electron microscopy, and X-ray diffraction. It was found that the units without defects positively impacted both the thermal fatigue resistance and tensile strength. The unit fabricated at a laser energy of

${165.6}_{- 15}^{+ 19}$ J/

${mm}^{2}$ had sufficient depth to fully close the crack, and exhibited superior anti-cracking and tensile properties. When the unit distance is 3 mm, the sample has excellent thermal fatigue resistance. In addition, the anti-crack mechanism of the units was analysed. Full article

(This article belongs to the Special Issue Advances in Laser Materials Processing)

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15 pages, 9182 KiB

Open AccessArticle

Effect of Composition on the Mechanical Properties and Wear Resistance of Low and Medium Carbon Steels with a Biomimetic Non-Smooth Surface Processed by Laser Remelting

by Geng Chang, Ti Zhou, Hong Zhou, Peng Zhang, Siyuan Ma, Benfeng Zhi and Siyang Wang

Metals 2020, 10(1), 37; https://doi.org/10.3390/met10010037 - 24 Dec 2019

Cited by 7 | Viewed by 2957

Abstract

To study the effect of laser biomimetic treatment on different material compositions, five kinds of steels with different carbon element contents were studied by laser remelting. The characteristics (depth, width), microstructure, hardness, tensile properties, and wear resistance of the samples were compared. The results show that when the laser processing parameters are fixed, the characteristics of the unit increase with an increase of carbon element content. Moreover, the hardness of the unit also increases. Compared with the untreated samples, when the carbon content is 0.15–0.45%, the tensile strength of the laser biomimetic samples is higher than that of the untreated samples. For the biomimetic samples with different carbon content, with an increase of carbon content, the tensile strength increases first and then decreases, while the plasticity of the biomimetic samples decreases continuously. The bionic samples have better wear resistance than that of the untreated samples. For bionic specimens with different carbon elements, wear resistance increases with an increase of carbon element content. Full article

(This article belongs to the Special Issue Advances in Laser Materials Processing)

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