The deformation behavior and mechanism of Ti2AlNb-based alloy were experimentally investigated at elevated temperatures. Firstly, the stress?strain relationships at different temperatures and strain rates were investi...The deformation behavior and mechanism of Ti2AlNb-based alloy were experimentally investigated at elevated temperatures. Firstly, the stress?strain relationships at different temperatures and strain rates were investigated via uniaxial tensile testing. Then, formability data, as determined by examining the deep drawing and bending abilities, were obtained through limiting draw ratio (LDR) and bending tests. Finally, metallographic experiments and fracture morphology investigations were conducted to examine the thermal deformation mechanism of the alloy. The results showed that as the temperature increased, the total elongation increased from 13.58% to 97.82% and the yield strength decreased from 788 to 80 MPa over the temperature range from 750 to 950 °C at a strain rate 0.001 s?1. When the temperature reached 950 °C, the strain rate was found to have a great influence on the deformation properties. The plastic formability of the sheet metal was significantly improved and a microstructuraltransformation of O toB2 andα2 occurred in this temperature region, revealing the deformation mechanism of its plasticity.展开更多
研究了CO2气体保护焊30Cr Mn Si A高强钢多次补焊对焊缝组织和疲劳性能的影响。结果显示,1次和2次补焊对原焊缝的显微组织和疲劳性能无明显影响,3次补焊后原焊缝晶界处出现块状铁素体,并有少量侧板条状铁素体,这导致3次补焊试样疲劳性...研究了CO2气体保护焊30Cr Mn Si A高强钢多次补焊对焊缝组织和疲劳性能的影响。结果显示,1次和2次补焊对原焊缝的显微组织和疲劳性能无明显影响,3次补焊后原焊缝晶界处出现块状铁素体,并有少量侧板条状铁素体,这导致3次补焊试样疲劳性能测试数据的分散性变大,且疲劳性能略有减少。同时发现,应力比R数值越大,则各组试样的疲劳寿命增加,而焊缝余高的存在对试样疲劳性能不利。展开更多
由于连杆是飞机发动机的重要组成部分,因此连杆生产效率对飞机发动机的生产量有很大的影响。以连杆生产线为研究对象,提出了结合ProModel软件和约束理论(Theory of Constraints,TOC)的优化制造系统方法。以TOC生产改善核心五步骤为主线,...由于连杆是飞机发动机的重要组成部分,因此连杆生产效率对飞机发动机的生产量有很大的影响。以连杆生产线为研究对象,提出了结合ProModel软件和约束理论(Theory of Constraints,TOC)的优化制造系统方法。以TOC生产改善核心五步骤为主线,TOC管理原则为指导,以ProModel模拟软件为主要分析工具,通过对企业的实际生产状况进行仿真分析,得到了连杆生产过程中的力能参数,并以仿真实验结果为依据,对生产过程中的各工位及生产设备的使用率进行了研究,找出了连杆在生产过程中所遇到的瓶颈。针对该瓶颈问题,制定了相应的连杆生产线优化方案,从而进一步提高了连杆的生产效率。展开更多
基金Project(XAEP-KIZ-KIB-1309-0063)supported by the Fundamental Research for General Armament Department,China
文摘The deformation behavior and mechanism of Ti2AlNb-based alloy were experimentally investigated at elevated temperatures. Firstly, the stress?strain relationships at different temperatures and strain rates were investigated via uniaxial tensile testing. Then, formability data, as determined by examining the deep drawing and bending abilities, were obtained through limiting draw ratio (LDR) and bending tests. Finally, metallographic experiments and fracture morphology investigations were conducted to examine the thermal deformation mechanism of the alloy. The results showed that as the temperature increased, the total elongation increased from 13.58% to 97.82% and the yield strength decreased from 788 to 80 MPa over the temperature range from 750 to 950 °C at a strain rate 0.001 s?1. When the temperature reached 950 °C, the strain rate was found to have a great influence on the deformation properties. The plastic formability of the sheet metal was significantly improved and a microstructuraltransformation of O toB2 andα2 occurred in this temperature region, revealing the deformation mechanism of its plasticity.
文摘研究了CO2气体保护焊30Cr Mn Si A高强钢多次补焊对焊缝组织和疲劳性能的影响。结果显示,1次和2次补焊对原焊缝的显微组织和疲劳性能无明显影响,3次补焊后原焊缝晶界处出现块状铁素体,并有少量侧板条状铁素体,这导致3次补焊试样疲劳性能测试数据的分散性变大,且疲劳性能略有减少。同时发现,应力比R数值越大,则各组试样的疲劳寿命增加,而焊缝余高的存在对试样疲劳性能不利。
文摘由于连杆是飞机发动机的重要组成部分,因此连杆生产效率对飞机发动机的生产量有很大的影响。以连杆生产线为研究对象,提出了结合ProModel软件和约束理论(Theory of Constraints,TOC)的优化制造系统方法。以TOC生产改善核心五步骤为主线,TOC管理原则为指导,以ProModel模拟软件为主要分析工具,通过对企业的实际生产状况进行仿真分析,得到了连杆生产过程中的力能参数,并以仿真实验结果为依据,对生产过程中的各工位及生产设备的使用率进行了研究,找出了连杆在生产过程中所遇到的瓶颈。针对该瓶颈问题,制定了相应的连杆生产线优化方案,从而进一步提高了连杆的生产效率。
文摘在单因素试验的基础上,采用响应面分析法对高产淀粉酶菌株的培养条件进行了优化.通过单因素试验,评价了不同温度、pH值、时间、碳源浓度、氮源浓度和摇床转速等6个因素对菌株产淀粉酶含量的影响.对蛋白胨质量分数、玉米粉质量分数、pH值和温度等主要影响因素进行中心组合设计,响应面分析结果为pH值对产酶影响显著,最佳培养条件为pH值为6.5,玉米粉质量分数为0.3%、蛋白胨质量分数为0.5%、培养温度为35℃、培养时间为30 h.
