A 40 Cr steel was formed into a chain-wheel using a warm extrusion technology. The surface roughness and micro-structure, micro-hardness and phases of the extruded samples at different temperatures were analyzed using...A 40 Cr steel was formed into a chain-wheel using a warm extrusion technology. The surface roughness and micro-structure, micro-hardness and phases of the extruded samples at different temperatures were analyzed using a three-dimensional optical microscope(OM), micro-hardness tester, and X-ray diffraction(XRD), respectively. The morphologies, chemical element distributions and phases of worn tracks at the extrusion temperatures of 550, 650 and 750 ℃ were analyzed using a scanning electron microscopy(SEM), energy disperse spectroscopy(EDS), and XRD, respectively. The friction-wear behaviors of extruded samples under oil-lubrication condition were observed using a wear test. And the effects of extrusion temperatures on the wear mechanism were discussed. The results show that residual austenite and pearlite exist on the sample at the extrusion temperature of 550 ℃ with the corresponding grain size and surface micro-hardness of 32.7 nm and 370.33 HV, respectively. The average coefficient of friction(COF) of extruded sample at the temperature of 550 ℃ is 0.196 5, and the wear mechanism is fatigue and abrasive wear. While the acicular martensite exists on the extruded samples at the extrusion temperatures of 650 and 750 ℃, the corresponding grain sizes are 30.0 and 29.1 nm, respectively. The average COF(coefficient of friction) of extruded sample at the temperatures of 650 and 750 ℃ are 0.187 4 and 0.163 6, respectively, and the wear mechanism is abrasive wear. As a result, the friction performance of extruded sample at the temperatures of 650 and 750 ℃ is better than that at the temperature of 550 ℃.展开更多
Co30Cr8W1.6C3Ni1.4Si coatings were fabricated on Ti6Al4V alloy using a laser thermal spraying(LTS).The surface and cross-section morphologies,phases and bonding strength of obtained coatings were investigated using sc...Co30Cr8W1.6C3Ni1.4Si coatings were fabricated on Ti6Al4V alloy using a laser thermal spraying(LTS).The surface and cross-section morphologies,phases and bonding strength of obtained coatings were investigated using scanning electronic microscopy(SEM),X-ray diffraction(XRD),and scratch test,respectively.The effects of laser power on the coefficients of friction(COFs)and corrosive-wear behaviors of Co30Cr8W1.6C3Ni1.4Si coatings were investigated using a wear tester in 3.5%NaCl solution,and the electrochemical corrosion performance was analyzed using an electrochemical workstation.The experimental results show that the Co30Cr8W1.6C3Ni1.4Si coating is bonded with the substrate in the metallurgical form,and the bonding strengths of Co30Cr8W1.6C3Ni1.4Si coatings fabricated at the laser power of 1000,1200,and 1400 W are 76.5,56.5,and 55.6 N,respectively.The average COFs of Co30Cr8W1.6C3Ni1.4Si coatings fabricated at the laser power of 1000,1200,and 1400 W are 0.769,0.893,and 0.941,respectively;and the corresponding wear rates are 0.267×105,0.3178×105,and 0.325×105μm3/Nm,respectively,which increases with the increase of laser power,the wear mechanism is primarily abrasive wear.The corrosion potential of Co30Cr8W1.6C3Ni1.4Si coatings fabricated at the laser power of 1000,1200,and 1400 W is-0.05,-0.25,and-0.31 V,respectively,higher than-0.45 V of substrate which enhances the electrochemical corrosion resistance of substrate.展开更多
Mechanics effect of laser thermal stress is a new manufacturing technology, which uses thermal stress by high power laser acted on the surface of metal material to produce stress field. The technologies such as sheet ...Mechanics effect of laser thermal stress is a new manufacturing technology, which uses thermal stress by high power laser acted on the surface of metal material to produce stress field. The technologies such as sheet metal formation by laser thermal stress, measurement by laser scratching and measurement by XRD (X-ray diffraction) are formed based on mechanics effects of laser thermal stress. The mechanisms of sheet metal formation by laser thermal stress, measurement by laser scratching and measurement by XRD are analyzed, and the theory of photo-mechanics manufacturing and detecting technologies based on laser thermal stress is originally put forward, whose experiment is primitively researched, and the manufacturing theory by mechanics effects of laser thermal stress is established.展开更多
基金Funded by Jiangsu Province Science and Technology Support Program(Industry)(No.BE2014818)the Research Project of Scientific Research Innovation for Graduate Students of Jiangsu Province(No.KYLX16-0631)
文摘A 40 Cr steel was formed into a chain-wheel using a warm extrusion technology. The surface roughness and micro-structure, micro-hardness and phases of the extruded samples at different temperatures were analyzed using a three-dimensional optical microscope(OM), micro-hardness tester, and X-ray diffraction(XRD), respectively. The morphologies, chemical element distributions and phases of worn tracks at the extrusion temperatures of 550, 650 and 750 ℃ were analyzed using a scanning electron microscopy(SEM), energy disperse spectroscopy(EDS), and XRD, respectively. The friction-wear behaviors of extruded samples under oil-lubrication condition were observed using a wear test. And the effects of extrusion temperatures on the wear mechanism were discussed. The results show that residual austenite and pearlite exist on the sample at the extrusion temperature of 550 ℃ with the corresponding grain size and surface micro-hardness of 32.7 nm and 370.33 HV, respectively. The average coefficient of friction(COF) of extruded sample at the temperature of 550 ℃ is 0.196 5, and the wear mechanism is fatigue and abrasive wear. While the acicular martensite exists on the extruded samples at the extrusion temperatures of 650 and 750 ℃, the corresponding grain sizes are 30.0 and 29.1 nm, respectively. The average COF(coefficient of friction) of extruded sample at the temperatures of 650 and 750 ℃ are 0.187 4 and 0.163 6, respectively, and the wear mechanism is abrasive wear. As a result, the friction performance of extruded sample at the temperatures of 650 and 750 ℃ is better than that at the temperature of 550 ℃.
基金Funded by the Key Research and Development Project of Jiangsu Province(BE2016052)。
文摘Co30Cr8W1.6C3Ni1.4Si coatings were fabricated on Ti6Al4V alloy using a laser thermal spraying(LTS).The surface and cross-section morphologies,phases and bonding strength of obtained coatings were investigated using scanning electronic microscopy(SEM),X-ray diffraction(XRD),and scratch test,respectively.The effects of laser power on the coefficients of friction(COFs)and corrosive-wear behaviors of Co30Cr8W1.6C3Ni1.4Si coatings were investigated using a wear tester in 3.5%NaCl solution,and the electrochemical corrosion performance was analyzed using an electrochemical workstation.The experimental results show that the Co30Cr8W1.6C3Ni1.4Si coating is bonded with the substrate in the metallurgical form,and the bonding strengths of Co30Cr8W1.6C3Ni1.4Si coatings fabricated at the laser power of 1000,1200,and 1400 W are 76.5,56.5,and 55.6 N,respectively.The average COFs of Co30Cr8W1.6C3Ni1.4Si coatings fabricated at the laser power of 1000,1200,and 1400 W are 0.769,0.893,and 0.941,respectively;and the corresponding wear rates are 0.267×105,0.3178×105,and 0.325×105μm3/Nm,respectively,which increases with the increase of laser power,the wear mechanism is primarily abrasive wear.The corrosion potential of Co30Cr8W1.6C3Ni1.4Si coatings fabricated at the laser power of 1000,1200,and 1400 W is-0.05,-0.25,and-0.31 V,respectively,higher than-0.45 V of substrate which enhances the electrochemical corrosion resistance of substrate.
基金this research from the Scientific Research Fund of Jiangsu Polytechnic University(GrantNo.ZMF07020042)Fund of Jiangsu ProvincialKey Laboratory for Science and Technology of Photo-manufacroring (Grant No.GZ-1-02)the NaturalScience Foundation of the Jiangsu Higher EducationInstitutions of China( Grant No. 08KJB430002 ) is gratefully acknowledged.
文摘Mechanics effect of laser thermal stress is a new manufacturing technology, which uses thermal stress by high power laser acted on the surface of metal material to produce stress field. The technologies such as sheet metal formation by laser thermal stress, measurement by laser scratching and measurement by XRD (X-ray diffraction) are formed based on mechanics effects of laser thermal stress. The mechanisms of sheet metal formation by laser thermal stress, measurement by laser scratching and measurement by XRD are analyzed, and the theory of photo-mechanics manufacturing and detecting technologies based on laser thermal stress is originally put forward, whose experiment is primitively researched, and the manufacturing theory by mechanics effects of laser thermal stress is established.
