In the present work,paraffin phase change material is used as quenchant for the heat treatment of 42CrMo4 alloy and compared with water,air,and CuO doped paraffin.The samples were prepared based on ASTM E 8M-98 standa...In the present work,paraffin phase change material is used as quenchant for the heat treatment of 42CrMo4 alloy and compared with water,air,and CuO doped paraffin.The samples were prepared based on ASTM E 8M-98 standard for tensile test and then heated up to 830°C,kept for 4 h in an electric resistance furnace and then quenched in the mentioned media.Elastic modulus,yield strength,ultimate tensile strength,elongation,and modulus of toughness were determined according to the obtained stress?strain curves.Moreover,the hardness and microstructural evolution were investigated after the heat treatment at different media.The samples quenched in paraffin and CuO-doped paraffin are higher in ultimate tensile strength(1439 and 1306 MPa,respectively)than those quenched in water(1190 MPa)and air(1010 MPa).The highest hardness,with a value of HV 552,belonged to the sample quenched in CuO-doped paraffin.The microstructural studies revealed that the non-tempered steel had a ferrite/pearlite microstructure,while by quenching in water,paraffin and CuO-doped paraffin,ferrite/martensite microstructures were achieved.It is also observed that using the air as quenchant resulted in a three-phase bainite/martensite/ferrite microstructure.展开更多
The composite plate made by explosion welding technology generally has high residual stress and bed plasticity due to the explosion reinforcement. The heat treatment can play a part of eliminating stress and recoverin...The composite plate made by explosion welding technology generally has high residual stress and bed plasticity due to the explosion reinforcement. The heat treatment can play a part of eliminating stress and recovering property.In this study,TA1/Q345 clad plate made by explosive welding was annealed at different temperatures.The microstructure,micro-hardness,and tensile,shear,and bending properties were analyzed after anneal.The result shows that there is fibrous structure in the bonding zone and the plastic deformation is severe,the grain growth and fibrous structure dribbles away with the temperature increasing.Micro-hardness in the interface is bigger than it on the both sides. Tensile and shear strength reduced with the temperature of heat treatment increasing.The propel anneal temperature for TA1/Q345 clad plate is 600展开更多
The Ti substrates of IrO 2 -Ta 2 O 5 coated anodes were treated by solid-solution and aging, stress relieving annealing, and recrystallization annealing, and the coatings were prepared by thermal decomposition of a mi...The Ti substrates of IrO 2 -Ta 2 O 5 coated anodes were treated by solid-solution and aging, stress relieving annealing, and recrystallization annealing, and the coatings were prepared by thermal decomposition of a mixture of H 2 IrCl 6 ·6H 2 O dissolved in hydrochloric acid and TaCl 5 dissolved in alcohol. Scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and accelerated life test (ALT) were employed to study the microstructure and electrochemical properties of the anodes. Compared with the anode without heat treatment, the anodes with heat treatment are of higher electrochemical activity and longer accelerated life; especially, the anode with recrystallization annealing treatment has the best electrochemical properties and the longest accelerated life.展开更多
Pinus massoniana L. was thermally treated with low melting point alloy as heating medium to investigate the strength properties changes. Contact angle, color and scanning electron microscopy were recorded to assess th...Pinus massoniana L. was thermally treated with low melting point alloy as heating medium to investigate the strength properties changes. Contact angle, color and scanning electron microscopy were recorded to assess the effectiveness of the treatment. Samples were pre-treated in a micro-wave for 5 min followed by metal bath heat treatment at 150, 180, and 210 °C for 2, 4, and 8 h,respectively. Strength properties of metal bath treated wood were decreased with increase temperature and time.Density, modulus of rupture, impact bending, modulus of elasticity were reduced for all treatments. Maximum compressive strength slightly increased at 150 °C for 4 h followed by gradual reduction. The Janka hardness was reduced in the tangential and radial directions. Treatment of the wood at 210 °C for 8 h caused the wood to become brittle and rupture. The contact angle was considerably higher after thermal treatment. The color of the wood became darker with increasing temperature of thermal treatment. Micrographs of the heat-treated samples showed damage to the cell wall with increase in temperature. Metal bath heat treatment of wood was carried out successfully and some strength properties were reduced.展开更多
The effects of heat treatment on the microstructure and mechanical properties of laser solid forming (LSF) Ti-6Al-4V alloy were investigated The influences of the temperature and time of solution treatment and aging...The effects of heat treatment on the microstructure and mechanical properties of laser solid forming (LSF) Ti-6Al-4V alloy were investigated The influences of the temperature and time of solution treatment and aging treatment were analyzed. The results show that the microstructure of LSFed samples consists of Widmanstatten α laths and a little acicular in columnar prior β grains with an average grain width of 300 μm, which grow epitaxiaUy from the substrate along the deposition direction (27). Solution treatment had an important effect on the width, aspect ratio, and volmne fraction of primary and secondary a laths, and aging treatment mainly affects the aspect ratio and volume fraction of primary α laths and the width and volume fraction of secondary a laths. Globular a phase was first observed in LSFed samples when the samples were heat treated with solution treatment (950℃, 8 h/air cooling (AC)) or with solution treatment (950℃, 1 h/AC) and aging treatment (550℃, above 8 h/AC), respectively. The coarsening and globularization mechanisms of a phase in LSFed Ti-6Al-4V alloy during heat treatment were presented. To obtain good integrated mechanical properties for LSFed Ti-6Al-4V alloys, an optimized heat treatment regimen was suggested.展开更多
文摘In the present work,paraffin phase change material is used as quenchant for the heat treatment of 42CrMo4 alloy and compared with water,air,and CuO doped paraffin.The samples were prepared based on ASTM E 8M-98 standard for tensile test and then heated up to 830°C,kept for 4 h in an electric resistance furnace and then quenched in the mentioned media.Elastic modulus,yield strength,ultimate tensile strength,elongation,and modulus of toughness were determined according to the obtained stress?strain curves.Moreover,the hardness and microstructural evolution were investigated after the heat treatment at different media.The samples quenched in paraffin and CuO-doped paraffin are higher in ultimate tensile strength(1439 and 1306 MPa,respectively)than those quenched in water(1190 MPa)and air(1010 MPa).The highest hardness,with a value of HV 552,belonged to the sample quenched in CuO-doped paraffin.The microstructural studies revealed that the non-tempered steel had a ferrite/pearlite microstructure,while by quenching in water,paraffin and CuO-doped paraffin,ferrite/martensite microstructures were achieved.It is also observed that using the air as quenchant resulted in a three-phase bainite/martensite/ferrite microstructure.
基金supported by National Natural Science Foundation of China(Grant No.51274162)Scientific Research Plan Project of Shaanxi Education Department(Grant No.14JK1539)Collaborative Innovation Project of Shaanxi Province(Grant No.2015XT-39)
文摘The composite plate made by explosion welding technology generally has high residual stress and bed plasticity due to the explosion reinforcement. The heat treatment can play a part of eliminating stress and recovering property.In this study,TA1/Q345 clad plate made by explosive welding was annealed at different temperatures.The microstructure,micro-hardness,and tensile,shear,and bending properties were analyzed after anneal.The result shows that there is fibrous structure in the bonding zone and the plastic deformation is severe,the grain growth and fibrous structure dribbles away with the temperature increasing.Micro-hardness in the interface is bigger than it on the both sides. Tensile and shear strength reduced with the temperature of heat treatment increasing.The propel anneal temperature for TA1/Q345 clad plate is 600
文摘The Ti substrates of IrO 2 -Ta 2 O 5 coated anodes were treated by solid-solution and aging, stress relieving annealing, and recrystallization annealing, and the coatings were prepared by thermal decomposition of a mixture of H 2 IrCl 6 ·6H 2 O dissolved in hydrochloric acid and TaCl 5 dissolved in alcohol. Scanning electron microscopy (SEM), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and accelerated life test (ALT) were employed to study the microstructure and electrochemical properties of the anodes. Compared with the anode without heat treatment, the anodes with heat treatment are of higher electrochemical activity and longer accelerated life; especially, the anode with recrystallization annealing treatment has the best electrochemical properties and the longest accelerated life.
基金financially supported by the Special Scientific Research Fund for Public Service Sectors of Forestry(Grant No.201504603)Science and Technology Projects of Fujian Province(2014NZ003)the National Natural Science Foundation of China(Grant Nos.31370560,31170520)
文摘Pinus massoniana L. was thermally treated with low melting point alloy as heating medium to investigate the strength properties changes. Contact angle, color and scanning electron microscopy were recorded to assess the effectiveness of the treatment. Samples were pre-treated in a micro-wave for 5 min followed by metal bath heat treatment at 150, 180, and 210 °C for 2, 4, and 8 h,respectively. Strength properties of metal bath treated wood were decreased with increase temperature and time.Density, modulus of rupture, impact bending, modulus of elasticity were reduced for all treatments. Maximum compressive strength slightly increased at 150 °C for 4 h followed by gradual reduction. The Janka hardness was reduced in the tangential and radial directions. Treatment of the wood at 210 °C for 8 h caused the wood to become brittle and rupture. The contact angle was considerably higher after thermal treatment. The color of the wood became darker with increasing temperature of thermal treatment. Micrographs of the heat-treated samples showed damage to the cell wall with increase in temperature. Metal bath heat treatment of wood was carried out successfully and some strength properties were reduced.
基金supported by the Program for New Century Excellent Talents in Universities of China (No.NCET-06-0879)the National Natural Science Foundation of China (No.50331010)+2 种基金the Northwestern Polytechnical University Foundation of Fundamental Research (No.NPU-FFR-JC200808)the National Basic Research Program of China (No.2007CB613800)the Program of Introducing Talents of Discipline to Universities,China (No.08040)
文摘The effects of heat treatment on the microstructure and mechanical properties of laser solid forming (LSF) Ti-6Al-4V alloy were investigated The influences of the temperature and time of solution treatment and aging treatment were analyzed. The results show that the microstructure of LSFed samples consists of Widmanstatten α laths and a little acicular in columnar prior β grains with an average grain width of 300 μm, which grow epitaxiaUy from the substrate along the deposition direction (27). Solution treatment had an important effect on the width, aspect ratio, and volmne fraction of primary and secondary a laths, and aging treatment mainly affects the aspect ratio and volume fraction of primary α laths and the width and volume fraction of secondary a laths. Globular a phase was first observed in LSFed samples when the samples were heat treated with solution treatment (950℃, 8 h/air cooling (AC)) or with solution treatment (950℃, 1 h/AC) and aging treatment (550℃, above 8 h/AC), respectively. The coarsening and globularization mechanisms of a phase in LSFed Ti-6Al-4V alloy during heat treatment were presented. To obtain good integrated mechanical properties for LSFed Ti-6Al-4V alloys, an optimized heat treatment regimen was suggested.