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Effect of CoNiCrAl coating and stress on creep microstructure and elemental diffusion of directionally solidified nickel-based superalloy

Liu Qian, Cao Tieshan, Wang Wei, Chi Qingxin, Cheng Congqian, Zhao Jie

Heat Treatment of Metals 2024, 49 (3): 262-268. doi:10.13251/j.issn.0254-6051.2024.03.043

Abstract （7）

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By designing the specimens with/without CoNiCrAl coatings as stepped ones to exclude other environmental factors, the effect of stress on the creep microstructure and elemental diffusion of DZ411 superalloy at 950 ℃ was studied, and the protective effect of the coating on the specimen was analyzed. The results show that the coating can significantly increase the creep life of the specimen. It is find that the greater the stress in the specimen, the higher the degree of degradation of the γ' phase and the higher the degree of compactness, especially the γ' phase in the high-stress zone is completely rafted, and that in the rest zones shows different degrees of spheroidization. The coating of the coated specimen in the high-stress zone is seriously damaged, while the coating in the low-stress and the non-stress zones only undergo slight oxidation. The degree of oxidation on the surface of the uncoated specimen increases with the increase of stress, though that in the high stress zone is more serious and with defects such as cracks and looseness, while the surface of the low stress position is still kept more complete. In addition, the element diffusion also changes with the stress, and different oxides are formed on the surface of the specimens, among which the Ti element content of the coated specimen gradually decreases from the matrix to the oxide layer surface, and decreases with the decrease of stress, while the Cr element content continues to increase from the surface to the inside and then decreases.

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Preparation and properties of TiC coating on 45 steel by laser cladding

Liu Zhiling, Chang Mingfeng, Han Guisheng, Dai Jiaoyan, Xu Jinfu

Heat Treatment of Metals 2024, 49 (3): 269-274. doi:10.13251/j.issn.0254-6051.2024.03.044

Abstract （8）

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TiC coatings were cladded on the surface of 45 steel by a CO₂ constant current laser using Ni60+TiC gradient layer structure. The effect of process parameters(laser power, scanning rate and overlap rate) on the microstructure and properties of TiC coatings was investigated. The results show that the surface cracks of the coating decrease and then increase with the increase of laser power and scanning rate. The surface cracks disappear when the laser power is 4.0 kW and the scanning rate is 400 mm/min. With the increase of the overlap rate, the surface cracks of the coating increase and then decrease, and the surface cracks of the coating disappear when the overlap rate is 50%. The optimal process parameters are laser power 4.0 kW, scanning rate 400 mm/min, and overlap rate 50%. The thickness of TiC gradient coating is about 1.2 mm after the best process, and it is metallurgically bonded with the base layer. The microstructure of the most superficial layer is dendritic TiC and a small amount of Ni-based solid solution, the microstructure of the gradient layer is TiC+Ni-based solid solution, TiC content from the surface to the inside is in a gradient decrease, Ni-based solid solution content from the surface to the inside is in a gradient increase. The hardness of TiC coating decreases from 1968 HV0.2 to 240 HV0.2. In addition, the wear rate of the TiC coating is 1.757×10^-15m³/(N·m).

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Effect of surface mechanical rolling treatment on microstructure and mechanical properties of annealed TWIP steel

Wang Fuxue, Li Jiahui, Wang Qiang, Wang Hongtao

Heat Treatment of Metals 2024, 49 (2): 274-280. doi:10.13251/j.issn.0254-6051.2024.02.043

Abstract （5）

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Twining-induced plastic deformation (TWIP) steel has low yield strength and high plasticity, which is not conducive to its popularization and application. In order to improve the comprehensive mechanical properties of the TWIP steel, the surface mechanical rolling treatment (SMRT) is used to introduce a strengthened layer with certain thickness on the surface of annealed low-stacking faults energy single-phase austenitic TWIP steel. The surface feature, microstructure and fracture morphologies were investigated by means of laser scanning confocal microscope, optical microscope and scanning electron microscope respectively, and the hardness gradient and tensile properties were evaluated by Vickers hardness tester and MTS universal testing system. The results show that after the SMRT, the TWIP steel surface forms a strengthened layer of about 1.4 mm in thickness, and with good surface integrity. The microstructure analysis shows that the surface grains are refined, and the dislocation density and deformation twin density are increased. The mechanical property test results show that the surface hardness of the TWIP steel after SMRT reaches 647.5 HV0.1, which is about 2 times higher than that of the as-annealed state, though it decreases gradually from the surface to the as-annealed hardness of 230 HV0.1. The yield strength, tensile strength, and percentage total extension at fracture of the as-annealed TWIP steel are about 270 MPa, 878 MPa, and 73%, respectively. After the SMRT, the yield strength of the TWIP steel is increased to 1008 MPa, which is increased to about 3.7 times that of the annealed; the tensile strength and percentage total extension at fracture are increased to 1142 MPa and to about 20.5%, respectively, showing excellent comprehensive mechanical properties.

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Influence of carrier gas flow rate on microstructure and corrosion resistance of laser clad Ni-based coatings with Y₂O₃

Li Yunfeng, Wang Jiasheng, Shi Yan, Jiang Guangjun, Tang Shufeng, He Xiaodong

Heat Treatment of Metals 2024, 49 (2): 281-290. doi:10.13251/j.issn.0254-6051.2024.02.044

Abstract （7）

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A 5 kW CO₂ laser was used for the preparation of pure Ni45 alloy coating and Ni45+0.4wt%Y₂O₃ coating on 42CrMoA steel substrate. Numerical simulation of the carrier gas flow rate was conducted using FLUENT software. The macroscopic morphologies and microstructure of the two coatings with different carrier gas flow rates were characterized using optical microscopy, scanning electron microscopy and XRD tester. The results show that as the carrier gas flow rate is increased from 500 L/h to 700 L/h, the powder deposition efficiency initially increases and then decreases. The solidification types of the two coatings consist of planar grains, cellular grains, columnar dendritic grains, and equiaxed grains, and with γ-Ni, M₂₃C₆, and Ni₃B phases. The microstructure refinement is most prominent when using a carrier gas flow rate of 600 L/h. The corrosion resistance increases initially, then decreases with the increase of carrier gas flow rate, and the coating produced with 600 L/h carrier gas flow rate has the best corrosion resistance.

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Optimization of process parameters for laser clad Ni-based coatings on gear steel surface

Shi Lubing, Du Jiajun, Zhang Zhihong, Ding Haohao, Wang Wenjian, Liu Zhongming

Heat Treatment of Metals 2023, 48 (11): 266-275. doi:10.13251/j.issn.0254-6051.2023.11.044

Abstract （16）

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Ni-based coating was fabricated on the surface of 18CrNiMo7-6 gear steel by laser cladding technique, and the effects of laser power, scanning speed, and powder feeding rate on the cladding quality and microstructure of Ni-based coating were investigated. The relationship between laser cladding process parameters and the macroscopic size, microstructure and microhardness of the clad coating was established. The results show that, with the increase of laser power, the melted height, width and depth of the coating increase, the microstructure is refined, and the microhardness increases. With the increase of scanning speed, the melted height and width of the coating increase, the melted depth decreases, the microstructure is coarsened, and the microhardness decreases. With the increase of powder feeding rate, the melted height of the coating increases, the melted width increases first and then decreases, the melted depth decreases, the microstructure is refined, and the microhardness increases. Based on the macroscopic morphology, microstructure and microhardness of the clad coating, the optimal process parameters are selected as the laser power of 700 W, scanning speed of 2 mm/s, and powder feeding rate of 11.1 g/min.

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Effect of Al addition on microstructure and wear resistance of Co-free high-entropy alloy coatings

Wei Shiyong, Wang Chaomin, Peng Wenyi, Chen Yun, Luo Rukai, Liu Wenzheng

Heat Treatment of Metals 2023, 48 (11): 276-281. doi:10.13251/j.issn.0254-6051.2023.11.045

Abstract （14）

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Al_xCrFeMnNi high-entropy alloy coatings (x=0.2,0.4,0.6,0.8,1) were successfully prepared on a Q235 steel substrate by plasma transfer arc. The influence of Al addition on the phase constituent, microstructure, and mechanical properties of the HEA coatings was investigated. The results show that, due to the high-entropy effect, the Al_xCrFeMnNi HEA coatings are mainly composed of simple BCC and FCC phases and a small amount of carbide phases. Moreover, the Al addition inhibits the formation of FCC phases, and the inter-dendritic areas are significantly increased with the increase of Al content. When the Al addition is 0.8, the average Vickers hardness of the HEA coating is 386.5 HV0.2, average friction coefficient is 0.595, and the most stable wear resistance is obtained.

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Effect of laser scanning rate on microstructure and wear resistance of NiCr/Cr₃C₂ coating

Dong Hui, Gan Shaoming, Du Yongqi, Bai Jiaxin, Cheng Yuchen, Li Ming, Zhu Chaoxuan

Heat Treatment of Metals 2023, 48 (11): 282-287. doi:10.13251/j.issn.0254-6051.2023.11.046

Abstract （12）

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NiCr/Cr₃C₂ composite coating was prepared by laser cladding at three laser scanning rates. The microstructure, hardness and friction and wear properties of the coatings were characterized using scanning electron microscope (SEM), X-ray diffractometer (XRD), micro-hardness tester and friction and wear testing machine. The results show that the structure in clad layer transfer from dendrite to equiaxed as the laser scanning rate increases from 2 mm/s to 4 mm/s, and the defects transfer from pores to large gaps and microcracks. When the scanning rate is below 3 mm/s, the melting and decomposition of Cr₃C₂ results in the clad layer mainly containing Cr₇C₃. As the laser scanning rate increases, the melting degree of Cr₃C₂ decreases, and the clad layer is mainly composed of Cr₇C₃ and Cr₃C₂. Therefore, the hardness of the clad layer increases from 400 HV0.3 to 780 HV0.3 when the laser scanning rate rises from 2 mm/s to 4 mm/s. The wear mechanism of the clad layer at different laser scanning rates is mainly abrasive wear, but due to its dense structure and higher hardness, the wear loss of the clad layer at scanning rate of 3 mm/s is the smallest and the wear resistance is the best.

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Properties of WC-25Co/NiCrAlY coating and its application in titanium alloy blade shoulder

Zhang Mourui, Liu Lixiang, Yu Ting, Li Changyin, Cui Yongjing

Heat Treatment of Metals 2023, 48 (11): 288-292. doi:10.13251/j.issn.0254-6051.2023.11.047

Abstract （13）

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NiCrAlY bottom layer and WC-25Co surface layer were prepared by spraying on TC6 titanium alloy specimens. The microstructure, microhardness, flexural behavior, bonding strength, thermal shock and wear behavior of the coating were studied. Based on the test results, a TC6 rotor blade of an aeroengine was taken as an example to verify the applicability of spraying coating on the blade shoulder, in particular, a long-term test evaluation of the coating was carried out. The results show that the coating has good comprehensive performance and can effectively improve the wear resistance and vibration of the shoulder of the TC6 rotor blades, meeting the requirements of aeroengines.

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Effect of laser quenching process parameters on microstructure and properties of Cr12MoV steel

Feng Aixin, Zhao Jian, Lin Jinhao

Heat Treatment of Metals 2023, 48 (10): 255-259. doi:10.13251/j.issn.0254-6051.2023.10.039

Abstract （32）

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Effect of laser quenching on microstructure and properties of Cr12MoV steel was studied, and the effects of different laser power (1050, 1200, 1350 W) and scanning speeds (3, 4, 5 mm/s) on microstructure, hardness and residual stresses of the laser quenching surface were analyzed. The results shows that after laser quenching, the surface hardness of the Cr12MoV steel increases obviously, and the surface residual stress changes from tensile stress to compressive stress. When the laser power is 1200 W and the scanning speed is 4 mm/s, the surface macromorphology is flat, the microstructure is refined, the surface microhardness reaches the maximum value of 653.68 HV, and the residual compressive stress reaches -259.29 MPa.

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Effects of WC content and heat treatment on microstructure and properties of WC-Fe60 clad layer

Gao Feng, Xue Ruilei, Man Jiao, Weng Yiqing, Zhou Jianping

Heat Treatment of Metals 2023, 48 (10): 260-265. doi:10.13251/j.issn.0254-6051.2023.10.040

Abstract （19）

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WC-Fe60 composite clad layers with WC (mass fraction of 0, 10% and 20%) were prepared on the surface of 20 steel by laser cladding technology. The 20%WC-Fe60 clad layer was heat treated at 600 ℃ and 800 ℃, respectively. And the effects of WC content and heat treatment on microstructure and properties of the WC-Fe60 clad layer were studied. The results show that the microstructure of the laser cladding WC-Fe60 composite clad layer is mainly composed of dendrites and equiaxed grains. With the increase of WC content, the number of dendrites in the clad layer decreases significantly, while the number of equiaxed crystals increases. The microhardness and wear resistance of the clad layer gradually improve, but the corrosion resistance decreases. After heat treatment, the microstructure of the 20%WC-Fe60 clad layer is smaller than that without heat treatment, and the microhardness, wear resistance and corrosion resistance are greatly improved. Among them, the clad layer after heat treatment at 600 ℃ obtains the best wear and corrosion resistance.

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Friction and wear performance of sulfurized layer on gray cast iron

Li Yelin, Jia Bo, Shi Zhengliang, Hu Wenxiang, Guan Yunqi, Zheng Huiyun

Heat Treatment of Metals 2023, 48 (10): 266-273. doi:10.13251/j.issn.0254-6051.2023.10.041

Abstract （28）

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Solid lubricating layers of sulfurized layer and phosphate layer were prepared on the surface of gray cast iron by low temperature ion sulfurization technology and chemical conversion technology, respectively. SEM-EDS, XRD, nano-indentation apparatus and X-ray stress analyzer were used to analyze the component elements, microstructure, thickness, hardness, residual stress and wear scar morphologies of the solid lubricating layers. The anti-friction and wear properties of the gray cast iron substrate and surface solid lubrication layer were studied by friction and wear test. The wear volume after friction and wear test was analyzed by using three-dimensional white light interferometer. The results show that both the phosphate layer and the porous structure of the sulfurized layer on the surface of gray cast iron have the characteristics of oil storage lubrication, while the surface hardness and residual stress of the sulfurized layer are higher than that of the phosphate layer. The sulfurized layer is detected to be a covalent bond compound FeS with antifriction and lubrication effect, which is formed when the active sulfur atoms infiltrate into the matrix, there is also a dynamic equilibrium process of active sulfur atoms transfer and recombination during the grinding process of gray cast iron substrate and sulfurized layer. Therefore, compared with the phosphate layer under the same friction conditions, the friction coefficient of the sulfurized layer is reduced by 23.5% and the wear rate is decreased by 31.6%, i.e., the anti-friction, wear-resisting and wear-resisting properties of sulfurized layer is better than that of phosphate layer, the COP of compressor parts after sulfurizing treatment is significantly improved.

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Microstructure and wear resistance of WC particle reinforced Fe based alloy coating

Gao Wandong

Heat Treatment of Metals 2023, 48 (10): 274-278. doi:10.13251/j.issn.0254-6051.2023.10.042

Abstract （31）

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Plasma melt injection(PMI) was used to prepare WC particles reinforced metal matrix composites layer on the 45 steel. During the PMI process, different voltage parameters were applied. The clad coating were analyzed by optical microscope (OM), scanning electron microscopy (SEM),X-ray diffraction(XRD) and energy dispersive spectrometer(EDS) to study microstructure, phase composition and chemical compositions of the clad coating. And a self-made friction and wear tester was used for wear characteristics analysis. SEM analysis result reveals that the clad coating, being metallurgical bonding with base material, is crack-free, and the WC particles distribute uniformly in the clad coating. In addition, the primary phase of the clad coating contains WC, W₂C, Cr₂₃C₆, Fe₃W₃C, Cr₃C₂ and Cr₇C₃. The maximum hardness of the clad coating is about 1600 HV. The friction and wear test results show that the wear loss of the plasma clad coating with WC reduces by more than 50% compared with that of the Fe based alloy coating. The main mechanism of wear is abrasive wear, with a large number of WC particles hindering micro cutting and exhibiting high wear resistance.

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Effect of heat treatment on microstructure and properties of coatings on GCr15 bearing steel prepared by flame spraying+induction remelting technology

Zhang Xi, Zhang Haoran, Xie Fang, Yan Jisen, Wu Bingbing, Kong Fanxiao

Heat Treatment of Metals 2023, 48 (8): 242-247. doi:10.13251/j.issn.0254-6051.2023.08.039

Abstract （37）

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Using Ni-Cr borosilicon powder (HG-201) as coating material, coatings on surface of GCr15 bearing steel were prepared by flame spraying+induction remelting composite melt coating technology, and then heat treated by different processes. Effects of different heat treatments on the microstructure, interface morphology, microhardness, impact property and impact fracture morphology of the coatings were studied by means of SEM, OM, microhardness test and impact test. The results show that the composite melt coating can refine the grain and improve the microhardness and impact property of GCr15 steel. The average impact absorbed energy of composite melt coated GCr15 steel is improved by 335.85% compared with that of conventional quenched GCr15 steel. After austempering or austempering+tempering treatment, the retained austenite and internal stress in the composite melt coated GCr15 steel are further eliminated, but the microhardness and impact property are slightly decreased, and the impact fracture of coatings shows the fracture mode of facet quasi-cleavage.

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Effect of scanning speed on microstructure and properties of 316L stainless steel coatings by high-speed laser cladding

He Wei, Wang Yanyan, Shu Linsen

Heat Treatment of Metals 2023, 48 (8): 248-253. doi:10.13251/j.issn.0254-6051.2023.08.040

Abstract （52）

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316L stainless steel coating was prepared on 27SiMn steel substrate by high-speed laser cladding technology, the surface morphology, microstructure, microhardness and friction and wear properties of the clad coating were tested and analyzed. The effect of scanning speed on microstructure and properties of high-speed laser clad coating was studied. The results show that, when the scanning speed is 75 mm/s, the coating quality and metallurgical combination effect is the best. The coating microstructure is uniform, the joint is dominated by cellular crystals, and the middle and upper part is dominated by columnar crystals and equiaxed dendrites without secondary crystal arms, with the increase of scanning speed, the grain is obviously refined. When the scanning speed is 105 mm/s, compared with the coating at scanning speed of 45 mm/s, the microhardness increases from 210.4 HV0.5 to 391.5 HV0.5, which increases by 1.87 times. The friction coefficient of the coating is 0.521, and the wear loss is 2 mg. Therefore, the macroscopic properties of the coating can be significantly improved with the increase of scanning speed, and the microhardness and wear resistance of the coating can be improved by the fine grain strengthening at high scanning speed.

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Microstructure and properties of magnetic field assisted hot dip aluminized coatings on TA15 titanium alloy surface

Li Yong, Wang Qiulin, Men Zhengxing, Zhao Yulin, Zhang Hong

Heat Treatment of Metals 2023, 48 (8): 254-259. doi:10.13251/j.issn.0254-6051.2023.08.041

Abstract （24）

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Microstructure and properties of hot dip aluminized coatings on the surface of TA15 titanium alloy under the action of alternating electromagnetic field were studied, and the thermal diffusion treatment was carried out at 800 ℃. The morphology, microstructure and element distribution of the coatings were analyzed by means of energy dispersive spectroscopy, scanning electron microscope and X-ray diffractometer. The microhardness of the coatings was tested by microhardness tester. The results show that after applying alternating electromagnetic field with current intensity of 15 A and 20 A during the process of hot dip aluminizing and thermal diffusion, the coatings bind well with the alloy substrate, no obvious crack is found, the formation of pores and cavities is significantly reduced, the dipping time is shortened, and thus the production cycle is accelerated. When the current intensity is 15 A and 20 A, the maximum hardness of the bonding zones can reach 518.7 HV0.2. When the current intensity increases to 25 A, the electromagnetic stirring effect sharply increases, and no high-quality coating can be obtained.

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Effect of laser shock peening on microstructure and fatigue property of TA15 titanium alloy with double holes

Han Peipei, Zang Xu, Dong Zhi, Li Shijian, Jiao Qingyang, Deng Xiguang

Heat Treatment of Metals 2023, 48 (7): 254-258. doi:10.13251/j.issn.0254-6051.2023.07.042

Abstract （22）

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TA15 titanium alloy were treated by laser shock peening (LSP) to study the effect of LSP on microstructure and fatigue property of the titanium alloy specimens with double holes. The results show that when the specimens are treated by LSP with laser energy of 25 J, circular spot diameter of ?4 mm and shock times of 2, a large number of high-density dislocations and dislocation walls are formed in the TA15 titanium alloy crystal, and introducing residual compressive stress of up to -500 MPa simultaneously on the material surface which can balance the tensile stress generated under fatigue load, effectively suppress fatigue crack initiation and slow down crack propagation rate. The LSP can obviously improve the fatigue life of the titanium alloy specimens with double holes, which is increased by 60%-89% compared to that of the untreated specimen. This is because the large residual compressive stress introduced by LSP greatly reduces the effective stress intensity factor at the crack tip. When the effective force intensity factor is less than the fracture toughness of the material, the fatigue crack growth will be suppressed or stopped, thus improving the fatigue life.

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Preparation of Al coatings by electro-explosive spray deposition

Zhou Yi, Zhu Liang, Duan Jingbang, Zhang Aihua, Zhou Hui, Yan Weiliang

Heat Treatment of Metals 2023, 48 (7): 259-265. doi:10.13251/j.issn.0254-6051.2023.07.043

Abstract （25）

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A method for preparing Al coating by tape-loaded wire-confined electric explosion method was proposed. Polyethylene tape as a carrier was used to load Al wire and to send it automatically and continuously into the explosion cavity to explode and prepare Al coating, and then the Al coatings under different process parameters were investigated. The results show that when the initial charging voltage of energy storage capacitor is 9.375 kV and the deposition distance is 26 mm, the surface of the coating is dense and uniform, and the deposition efficiency is relatively high (about 51%), the surface roughness R_a of the coating is reduced from 2.51 μm to 1.29 μm, the maximum hardness of the layer is 116.8 HV and the thickness is about 200 μm. The coating and the substrate are typical metallurgical bonding. By the bending test carries out according to the national standard GB/T 5270—2005 “Metallic coatings on metallic substrates—Electrodeposited and chemically deposited coatings-Review of methods available for testing adhesion”, the result shows that there is no tearing, peeling or debonding between the coating and the substrate, which indicates a good adhesion strength between the coating and the substrate. It is concluded that the preparation of Al coating can be successfully realized by the method of restrained electric explosion with carrier wire.

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Laser quenching process optimization and microstructure and properties of H13 steel

Ma Xin, Shi Qiang, Chen Yanzhong, Li Qiang, Zhang Yueting, Zhao Long

Heat Treatment of Metals 2023, 48 (7): 266-270. doi:10.13251/j.issn.0254-6051.2023.07.044

Abstract （26）

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Surface of H13 steel was strengthened by laser quenching, and the quenching process was optimized by range analysis of orthogonal test. The microhardness and friction and wear properties of the specimen under the optimum process parameters were studied, and the phase composition and microstructure of the laser quenching surface were analyzed. The results show that the optimum laser quenching process parameters are laser power of 600 W, scanning speed of 6 mm/s and lapping rate of 20%. Under this optimum process, the average hardness of hardened layer of the H13 steel is 774 HV0.1, which is about 3 times than that of the matrix, the depth of the hardened layer is 0.87 mm, and the friction coefficient and wear amount are about 0.367 and 0.0015 g, which are 50% and 60.5% lower than those of the matrix, respectively. The hardened layer is mainly composed of lath and acicular mixed martensite, retained austenite and a small amount of cementite.

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Effect of heat treatment on hardness and wear resistance of laser clad Co-based alloy coating

Yang Dongjie, Bai Qiaofeng, Ouyang Changyao, Wang Rui, Wei Runze

Heat Treatment of Metals 2023, 48 (7): 271-276. doi:10.13251/j.issn.0254-6051.2023.07.045

Abstract （22）

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Co-based alloy coating was prepared on the surface of ductile iron by laser cladding technology. Microstructure of the specimens under different heat treatment processes was analyzed and the effects of different processes on the hardness and wear resistance of the cobalt-based alloy coating were discussed. Compared with untreated specimens, the hardness of heat-treated specimens is improved. The hardness changes of the specimens treated at 950 ℃ for 1 h and 2 h, respectively, are similar, which are 51.35 HRC and 51.15 HRC, and that subsequent aged at 825 ℃ are 52.50 HRC and 52.08 HRC. The wear amount of the untreated specimen is the highest and the wear resistance is the worst. The wear loss of the specimen treated by 950 ℃×1 h + 825 ℃×24 h reduces by 5.3%, and that of the treated by 950 ℃×3 h+825 ℃×24 h reduces by 12.8%, which shows better wear resistance.

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Static oxidation behavior at high temperature of laser-assisted thermal sprayed NiCoCrAlYTa-Cr₂O₃-Cu-Mo coating

Nie Zixing, Wang Changliang, Zhang Ang, Zhang Mei, Guo Mengqiu, Tian Haoliang, Cui Yongjing, Wang Tianying

Heat Treatment of Metals 2023, 48 (2): 247-255. doi:10.13251/j.issn.0254-6051.2023.02.039

Abstract （16）

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NiCoCrAlYTa-Cr₂O₃-Cu-Mo high temperature lubrication wear-resistant coating was prepared on the GH4065A nickel-based superalloy by laser-assisted plasma spraying (LPHS) technology, and then the high temperature oxidation resistance of the coating at 850-1000 ℃ for 220 h was investigated. The calculated oxidation activation energy is about 128.5 kJ·mol^-1, and the oxidation rate constants at 850, 900 and 1000 ℃ are 1.44×10^-2, 3.61×10^-2, 7.71×10^-2 mg²·cm^-4·h^-1, respectively. The experimental results show that after oxidation at 850 ℃ for 220 h, a continuous and dense oxide film dominated by Al₂O₃ is formed on the surface, which can prevent the further oxidation inside the coating. After oxidation at 1000 ℃ for 220 h, an oxide film consisting mainly of loose NiO and supplemented by dense Cr₂O₃·NiO is formed on the surface. The formation of dense oxide film prevents further oxidation of both the coating and the GH4065A superalloy substrate.

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