Microstructural evolution of AZ91 magnesium alloy was investigated during homogenizing annealing treatment, hot extrusion and ageing treatment, respectively. The results exhibited that both the divorced eutectic β-Mg...Microstructural evolution of AZ91 magnesium alloy was investigated during homogenizing annealing treatment, hot extrusion and ageing treatment, respectively. The results exhibited that both the divorced eutectic β-Mg17Al12 and the precipitated β-Mg17Al12 phases appeared in the as-cast alloy. The β-Mg17Al12 phase dissolved into α-Mg matrix mostly and the structure kept fine after the optimized homogenization treatment at 380 °C for 15 h. Dynamic recrystallization and consequent grain refinement occurred during extrusion. The banded β-Mg17Al12 precipitates paralleled to the extrusion direction were observed after ageing treatment. The banded precipitation should be attributed to the solidification segregation which was elongated during the subsequent extrusion. Furthermore, the effects of temperature, holding time of homogenization and ageing treatment, and extrusion processing parameters on the microstructural evolution of AZ91 alloy were also discussed in details according to the experimental results.展开更多
The effects of heat treatment and strontium （SO addition on the microstructure and mechanical properties of ADC12 alloys were investigated, and two-stage solution treatment was introduced. The results indicated that ...The effects of heat treatment and strontium （SO addition on the microstructure and mechanical properties of ADC12 alloys were investigated, and two-stage solution treatment was introduced. The results indicated that the addition of Sr obviously refined the microstructure of ADC12 alloys. When 0.05 wt% Sr was added into the alloy, the eutectic Si phase was fully modified into fine fibrous structure; a-A1 and fl-A15FeSi phases were best refined; and the eutectic AlzCu phase was modified into block-like AlzCu phase that continuously distributed at the grain boundary. The ultimate tensile strength （UTS） （270.63 MPa） and elongation （3.19%） were increased by 51.2% and 73.4% respectively compared with unmodified alloys. After the two-stage solution treatment （500 ~C, 6 h＋520 ~C, 4 h）, for 0.05 wt% Sr modified ADC12 alloys, the Si phases transformed into fine particle structure and AlzCu phases were fully dissolved. The peak hardness value of the alloys processed by the two-stage solution treatment was increased by 8.3% and 6.8% respectively compared to solution treatment at 500 ~C and 520 ~C. After the aging treatment （175 ~C, 7 h）, the hardness and UTS were increased by 38.73% and 13.96% respectively when compared with the unmodified alloy.展开更多
The effects of Mg enhancement and heat treatment on the microstructures and tensile properties of Al_2Ca-added ADC12 die casting alloys were investigated. 0.3% and 0.5% Mg in the form of a master alloy including a tra...The effects of Mg enhancement and heat treatment on the microstructures and tensile properties of Al_2Ca-added ADC12 die casting alloys were investigated. 0.3% and 0.5% Mg in the form of a master alloy including a trace amount of Al_2Ca were added to conventional ADC12（383 and AlSi10Cu2Fe） alloy with an initial Mg-content of 0.3% to increase the Mg content to 0.6% and 0.8%, respectively. To avoid heat treatmentinduced surface blisters, shortened solution treatment for 15 min at 490 ℃ and artificial aging for 6 h at 150 ℃ was undertaken. The results show that a 10% improvement in the shape factor of eutectic Si particles was achieved for Al_2Ca-added ADC12 with 0.8% Mg compared to the conventional ADC12 in the as-aged condition. Al_2Ca-added ADC12 with 0.8% Mg exhibited a yield strength of 289 MPa, a tensile strength of 407 MPa, and an elongation of 4.22%.展开更多
A series of heat treatments using the orthogonal experiment method were performed to study the microstruc- ture and mechanical properties of 1Cr12NiMo martensitic stainless steel containing various nitrogen content ad...A series of heat treatments using the orthogonal experiment method were performed to study the microstruc- ture and mechanical properties of 1Cr12NiMo martensitic stainless steel containing various nitrogen content addition. The results indicate that the optimal heat treatment is annealing at 830 ℃ for 1 h, austenitizing at 985 ℃ for 1 h followed by oil quenching, and tempering at 630 ℃ for 4 h followed by air cooling, Nitrogen addition to 1Cr12NiMo steel can effectively hinder the austenite grain growth, refine the martensite lath, and increase the strength and hardness. The impact toughness of this steel only shows a minor decrease as the nitrogen content increases.展开更多
采用熔化极活性气体保护焊(metal active gas arc welding,MAG焊)、等离子弧焊(plasma arc welding,PAW)和高频感应焊接方法获得铁素体+马氏体双相组织不锈钢00Cr12Ni的焊接接头,对其组织区域特征和力学性能进行了研究.典型的焊接接头...采用熔化极活性气体保护焊(metal active gas arc welding,MAG焊)、等离子弧焊(plasma arc welding,PAW)和高频感应焊接方法获得铁素体+马氏体双相组织不锈钢00Cr12Ni的焊接接头,对其组织区域特征和力学性能进行了研究.典型的焊接接头热影响区(heat affected zone,HAZ)可分为晶粒粗大,铁素体为优势相的高温热影响区(high temperature heat affected zone,HTHAZ)和晶粒细小,马氏体为优势相的低温热影响区(low temperature heat affected zone,LTHAZ).通过测量实际焊接热循环曲线的方法确定了HTHAZ及LTHAZ的温度范围,并采用热模拟研究HAZ不同区域的力学性能.结果表明,HTHAZ的热循环峰值范围为1200℃至熔点,晶粒粗大呈现为脆性;LTHAZ热循环峰值范围为800~1200℃,室温组织为非平衡低碳板条马氏体,韧性较好,但低于0℃时呈脆性.MAG焊接头由于奥氏体焊缝为钟罩形,HAZ冲击试验时断面包括奥氏体焊缝,因此冲击性能较好;PAW接头在1000℃奥氏体快冷可获得细晶粒马氏体韧性提高;高频感应焊接接头中无HTHAZ,但焊接过程中的加工硬化导致室温呈脆性,通过去应力退火后韧性恢复.展开更多
Influence of different extrusion pressures and pouring temperatures on comprehensive performance of(Al63Cu25Fe12)p/ZL101 composites is studied in this paper.The results show that the tensile strength,elongation and ha...Influence of different extrusion pressures and pouring temperatures on comprehensive performance of(Al63Cu25Fe12)p/ZL101 composites is studied in this paper.The results show that the tensile strength,elongation and hardness of(Al63Cu25Fe12)p/ZL101 composite increase with the squeezing pressure increasing from 50 MPa to 100 MPa,and gradually reduce from 100 MPa to 150 MPa.In addition,the mechanical properties of the composite can be improved with pouring temperature growing,while the temperature should not exceed 760℃.When squeezing pressure is 100 MPa and pouring temperature is 720℃,mechanical properties of composites are the best.Finally,the mechanical properties of(Al 63 Cu 25 Fe 12)p/ZL101 composite will be improved by suitable heat treatment technology展开更多
基金Project (2011A090200104) supported by Guangdong Science and Technology Special Projects, China
文摘Microstructural evolution of AZ91 magnesium alloy was investigated during homogenizing annealing treatment, hot extrusion and ageing treatment, respectively. The results exhibited that both the divorced eutectic β-Mg17Al12 and the precipitated β-Mg17Al12 phases appeared in the as-cast alloy. The β-Mg17Al12 phase dissolved into α-Mg matrix mostly and the structure kept fine after the optimized homogenization treatment at 380 °C for 15 h. Dynamic recrystallization and consequent grain refinement occurred during extrusion. The banded β-Mg17Al12 precipitates paralleled to the extrusion direction were observed after ageing treatment. The banded precipitation should be attributed to the solidification segregation which was elongated during the subsequent extrusion. Furthermore, the effects of temperature, holding time of homogenization and ageing treatment, and extrusion processing parameters on the microstructural evolution of AZ91 alloy were also discussed in details according to the experimental results.
基金Project（51364035） supported by the National Natural Science Foundation of China Project（20133601110001） supported by the Ministry of Education Tied up with the Special Research Fund for the Doctoral Program for Higher School, China+1 种基金 Project（KJLD14003） supported by the Loading Program of Science and Technology of College of Jiangxi Province, China Project（2012-CYH-DW-XCL-002） supported by the Production and Teaching and Research Cooperation Plan of Naaachaaag Non-party Experts and Doctor, China
文摘The effects of heat treatment and strontium （SO addition on the microstructure and mechanical properties of ADC12 alloys were investigated, and two-stage solution treatment was introduced. The results indicated that the addition of Sr obviously refined the microstructure of ADC12 alloys. When 0.05 wt% Sr was added into the alloy, the eutectic Si phase was fully modified into fine fibrous structure; a-A1 and fl-A15FeSi phases were best refined; and the eutectic AlzCu phase was modified into block-like AlzCu phase that continuously distributed at the grain boundary. The ultimate tensile strength （UTS） （270.63 MPa） and elongation （3.19%） were increased by 51.2% and 73.4% respectively compared with unmodified alloys. After the two-stage solution treatment （500 ~C, 6 h＋520 ~C, 4 h）, for 0.05 wt% Sr modified ADC12 alloys, the Si phases transformed into fine particle structure and AlzCu phases were fully dissolved. The peak hardness value of the alloys processed by the two-stage solution treatment was increased by 8.3% and 6.8% respectively compared to solution treatment at 500 ~C and 520 ~C. After the aging treatment （175 ~C, 7 h）, the hardness and UTS were increased by 38.73% and 13.96% respectively when compared with the unmodified alloy.
文摘The effects of Mg enhancement and heat treatment on the microstructures and tensile properties of Al_2Ca-added ADC12 die casting alloys were investigated. 0.3% and 0.5% Mg in the form of a master alloy including a trace amount of Al_2Ca were added to conventional ADC12（383 and AlSi10Cu2Fe） alloy with an initial Mg-content of 0.3% to increase the Mg content to 0.6% and 0.8%, respectively. To avoid heat treatmentinduced surface blisters, shortened solution treatment for 15 min at 490 ℃ and artificial aging for 6 h at 150 ℃ was undertaken. The results show that a 10% improvement in the shape factor of eutectic Si particles was achieved for Al_2Ca-added ADC12 with 0.8% Mg compared to the conventional ADC12 in the as-aged condition. Al_2Ca-added ADC12 with 0.8% Mg exhibited a yield strength of 289 MPa, a tensile strength of 407 MPa, and an elongation of 4.22%.
基金supported by the National Key Technology R&D Program,China(No.2011BAA06B02)
文摘A series of heat treatments using the orthogonal experiment method were performed to study the microstruc- ture and mechanical properties of 1Cr12NiMo martensitic stainless steel containing various nitrogen content addition. The results indicate that the optimal heat treatment is annealing at 830 ℃ for 1 h, austenitizing at 985 ℃ for 1 h followed by oil quenching, and tempering at 630 ℃ for 4 h followed by air cooling, Nitrogen addition to 1Cr12NiMo steel can effectively hinder the austenite grain growth, refine the martensite lath, and increase the strength and hardness. The impact toughness of this steel only shows a minor decrease as the nitrogen content increases.
文摘采用熔化极活性气体保护焊(metal active gas arc welding,MAG焊)、等离子弧焊(plasma arc welding,PAW)和高频感应焊接方法获得铁素体+马氏体双相组织不锈钢00Cr12Ni的焊接接头,对其组织区域特征和力学性能进行了研究.典型的焊接接头热影响区(heat affected zone,HAZ)可分为晶粒粗大,铁素体为优势相的高温热影响区(high temperature heat affected zone,HTHAZ)和晶粒细小,马氏体为优势相的低温热影响区(low temperature heat affected zone,LTHAZ).通过测量实际焊接热循环曲线的方法确定了HTHAZ及LTHAZ的温度范围,并采用热模拟研究HAZ不同区域的力学性能.结果表明,HTHAZ的热循环峰值范围为1200℃至熔点,晶粒粗大呈现为脆性;LTHAZ热循环峰值范围为800~1200℃,室温组织为非平衡低碳板条马氏体,韧性较好,但低于0℃时呈脆性.MAG焊接头由于奥氏体焊缝为钟罩形,HAZ冲击试验时断面包括奥氏体焊缝,因此冲击性能较好;PAW接头在1000℃奥氏体快冷可获得细晶粒马氏体韧性提高;高频感应焊接接头中无HTHAZ,但焊接过程中的加工硬化导致室温呈脆性,通过去应力退火后韧性恢复.
基金National Natural Science Foundation of China(Nos.U1610123,51674226,51574207,51574206)International Cooperation Project of the Ministry of Science and Technology of China(No.2014DFA50320)+3 种基金Science and Technology Major Project of Shanxi Province(No.MC2016-06)International Science and Technology Cooperation Project of Shanxi Province(No.2015081041)Research Project Supported by Shanxi Scholarship Council of China(No.2016-Key 2)Transformation of Scientific and Technological Achievements Special Guide Project of Shanxi Province(No.201604D131029)
文摘Influence of different extrusion pressures and pouring temperatures on comprehensive performance of(Al63Cu25Fe12)p/ZL101 composites is studied in this paper.The results show that the tensile strength,elongation and hardness of(Al63Cu25Fe12)p/ZL101 composite increase with the squeezing pressure increasing from 50 MPa to 100 MPa,and gradually reduce from 100 MPa to 150 MPa.In addition,the mechanical properties of the composite can be improved with pouring temperature growing,while the temperature should not exceed 760℃.When squeezing pressure is 100 MPa and pouring temperature is 720℃,mechanical properties of composites are the best.Finally,the mechanical properties of(Al 63 Cu 25 Fe 12)p/ZL101 composite will be improved by suitable heat treatment technology
