12Ni3MoV钢焊接HAZ中的粒状组织

本文用热模拟技术研究了低温球罐用钢12Ni3MoV钢模拟焊接HAZ中的粒状组织和粒状贝氏体的组织形态、形成过程及影响因素。研究结果表明,12Ni3MoV钢两相区和细晶区的组织为粒状组织,粗晶区的组织为侧板条粒状贝氏体和针片状粒状贝氏体。奥氏体状态对冷却后的转变产物育显著的影响。奥氏体晶粒细小或奥氏体成分不均匀,冷却过程中易形成粒状组织,奥氏体晶粒粗大,且成分均匀,冷却过程中易形成粒状贝氏体。     

基于MC9S12DP256的汽车ABS数据采集系统设计

设计了基于MC9S12DP256单片机的汽车ABS数据采集系统;详细介绍了该系统的硬件电路以及系统软件设计.大量的ABS实车实验证明:该数据采集系统工作性能良好,可靠性高.采集数据的精度完全可以满足汽车ABS系统的要求.     

Preparation of epitaxial and polycrystalline bismuth titanate thin films on single crystal (100) MgO by chemical solution deposition

Epitaxial and polycrystalline Bi₄Ti₃O₁₂ thin films were prepared on single crystal (100) MgO substrates by a chemical solution deposition process using metal naphthenates as starting materials. Pyrolyzed films (at 500°C) were annealed for 30 min in air at 650, 700, 750 and 800°C, respectively. The effects of annealing temperature on the crystallinity, epitaxy and surface morphology of the films were investigated by X-ray diffraction θ-2θ scans, pole-figure analysis, and atomic force microscopy (AFM). Epitaxially grown films annealed at 700 and 750°C, respectively, showed growth of three-dimensional needle-shaped grains. During annealing at 800°C, grain growth of Bi₄Ti₃O₁₂ may be suppressed by the formation of a titanium-rich phase such as Bi₂Ti₂O₇ owing to Bi volatilization, resulting in lower root mean square roughness than that of film annealed at 750°C.     

热处理工艺参数对2A12铝合金镍磷镀层性能的影响

研究了2A12铝合金表面镍磷合金镀层的性能及热处理温度对镀层硬度、耐磨性、磨损速率等的影响.     

Al2Mo3-xWxO12的合成及热膨胀特性的研究

使用共沉淀法合成了完全固溶的Al2Mo3-xWxO12系列粉体材料，用热机械分析(TMA)压缩法测定其热膨胀系数，发现Al2Mo3-xWxO12的单斜-正交转变温度随x增加而下降；通过调整材料的组成，可以控制材料的热膨胀系数，并有望在此类材料中获得近零或负热膨胀材料。但是由于其结构的各向异性，多晶陶瓷内部存在的微裂纹使热膨胀曲线出现较大的滞后环。     

In situ repair welding of steam turbine shroud for replacing a cracked blade

A root-cracked blade in a high-pressure steam turbine of a nuclear power plant had to be replaced with a new blade by cutting the shroud to remove the cracked blade. This necessitated in situ welding of a new shroud piece with the existing shroud after the blade replacement. The in situ welding of the shroud, a 12% Cr martensitic stainless steel with tempered martensite microstructure, was carried out using gastungsten arc welding and 316L austenitic stainless steel filler metal followed by localized postweld heat treatment at 873 K for 1 h using a specially designed electrical resistance-heating furnace. Mock-up trials were carried out to ensure that sound welds could be made under the constraints present during the in situ repair welding operation. In situ metallography of the repair weld after postweld heat treatment confirmed the adequate tempering of the martensitic structure in the heat-affected zone. Metallurgical investigations carried out in the laboratory on a shroud test-piece that had been welded using the same procedure as employed in the field confirmed the success of the in situ repair operation. The alternate option available was replacing the cracked blade and the shroud piece to which it is riveted with a new one, reducing the height of all the blades attached to the shroud by machining, riveting the blades with reduced height to the new shroud, and, finally, dynamic balancing of the entire turbine after completion of the repair. This option is both time-consuming and expensive. Hence, the successful completion of this repair welding resulted in enormous savings both in terms of reducing the downtime of the plant and the cost of the repair. The turbine has been put back into service and has been operating satisfactorily since December 2000.     

铝合金搅拌摩擦焊焊接缺陷分析

采用搅拌摩擦焊方法对6mm厚的2A12及3A21铝合金进行焊接。对其焊接速度、旋转速度及压入量等工艺参数选择不当所产生的接头缺陷进行了分析;焊接缺陷的产生与焊接热输入及焊缝塑性金属的软化相关。当热输入不足或者塑性金属的软化程度较差时都会导致焊接缺陷的形成。     

基于USB总线的数据采集系统

介绍了一种USB数据采集系统的实现方法，该系统采用Philips公司的PDIUSBD12接口芯片。本文具体介绍了该数据采集系统的硬件、Firmware（固件）、基于Windows驱动程序模型（WDM）的设备驱动程序以及应用软件的设计。     

2A12铝合金形变热处理工艺在旋压工艺中的应用

采用工艺实验研究2A12铝合金形变热处理工艺中时效温度和室温塑性变形量对材料性能的影响。结果表明:经固溶/淬火+8%室温塑性变形+(140±5)℃,15 h,及空冷人工时效工艺处理后,2A12铝合金获得良好的强塑性配合;在2A12铝合金热挤压管材旋压工艺中采用形变热处理技术,可以使旋压工件材料的综合性能得到明显提高。     

12Cr1MoVG焊接接头高温短时拉伸及可靠性评价

分别对焊态和焊后热处理(PWHT)的12Cr1MoVG钢焊接接头进行300~600℃高温短时拉伸试验,根据该试验结果可以推算出接头的持久强度。结果表明,随测试温度的升高,两种接头的高温短时拉伸强度降低,伸长率升高。断口形貌分析表明接头的断裂机制由剪切断逐渐过渡到正断。焊态接头的高温短时拉伸强度均高于PWHT态接头。510℃时,焊态及PWHT态接头的持久强度下限(σ105783)分别为61 MPa和86 MPa,均大于某电站锅炉的额定蒸气压力(30.35 MPa)。PWHT态12Cr1MoVG钢接头具有较高的持久强度,因而具有更高的服役可靠性。