发动机高压涡轮转子卡滞分析

发动机地面起动时高压涡轮转子卡滞,通过对该发动机卡滞物及正面环喷管断口的失效分析认为,卡滞原因是由于正面环喷管平面与正面环的球面组合时有不同程度的间隙,在间隙大的部位采用搭桥焊接,焊点细腰部位产生横向收缩裂纹,在校正喷管角度时应力过大,裂纹扩展直至断裂,在工作过程中当3个焊点全部断裂时,正面环喷管脱落并卡滞在高压涡轮工作叶片之间,导致转子卡滞。通过改进焊接工艺,取消校正工艺,加强焊后检查,能有效预防正面环喷管脱落而导致的高压转子卡滞故障。     

镍基合金K4648焊接接头疲劳裂纹扩展速率的研究

为了对某飞机发动机涡轮导向器叶片修复焊接后的安全性和寿命进行评估,试验研究了导向器叶片用K4648合金TIG焊接头的疲劳裂纹扩展速率(da/dN- △K).分别测得了K4648合金母材、焊缝和热影响区疲劳裂纹扩展速率的表达式,对各区域的显微组织特征进行了观察,并测量了3个区域的硬度.结果表明:裂纹在母材中最容易扩展,在...     

修复

高铬铸铁堆焊工艺试验研究；抗磨铸钢件的焊接修复；风机断裂轴焊接修复工艺；日产不锈钢薄钢带的修复；670t／h电站锅炉汽包裂纹焊接修复；轧辊修复技术的研究现状和展望；烧结台车车体的堆焊修复；焊接修复；输气管道连接器在服役状态下修补焊接的数字模拟；维修透平壳体的实践；高效自动化埋弧堆焊过程；∏C-90A航空发动机高压室动叶片自动化堆焊修复工艺。[编者按]     

CO2激光熔覆修复涡轮导向器工艺初探

为研究修复K418涡轮导向器的工艺,以CO2连续激光器为热源,在涡轮导向器试验叶片表面熔覆自配粉末,获得了微观形貌和显微硬度均优于基体组织的熔覆层.结果表明:在激光功率为800W、扫描速度为5mm/s、气流量为1L/min时,熔覆层的组织晶粒更加致密细小,与基体呈冶金结合且无微观缺陷.熔覆层最高硬度达436.2HV,是基体硬度的1.2倍.但采用CO2激光器容易造成热作用区增大,后续将改用YAG脉冲激光器作热源,并优化材料参数和工艺参数,进一步研究修复K418涡轮导向器的新工艺.     

K417G合金焊接修复用高温合金粉末设计与工艺

航空发动机涡轮导向叶片在服役过程中形成的裂纹可以采用钎焊粉末冶金修复技术进行修复,针对低压涡轮导向叶片材料和结构特点,设计了K417G合金修复所需的不同成分的粉末填充材料,测试了不同粉末粒度配比的振实密度值,采用金相法、压汞法评估了不同烧结条件下粉末烧结体的孔隙率、平均孔径、中值孔径、最可几孔径等烧结体性能值,优选了粉末填充材料,在此基础上开展了钎焊粉末冶金修复工艺研究,分析测试了钎焊粉末冶金修复接头冶金组织. 结果表明,接头成形良好,焊料润湿铺展充分,接头致密饱满,无明显焊接缺陷.     

某型航空发动机高导内机匣安装边密集裂纹原因分析与焊接修复

某型航空发动机高导内机匣大修时,装配导向器叶片的卡槽安装边出现密集裂纹,采用氩弧焊焊修,不仅使卡槽变形易超过技术要求,且在非裂纹区域产生了新的裂纹。重复焊修又会产生新的裂纹,形成恶性循环,造成产品报废。文中通过分析故障原因,找到症结所在,研究合理高导内机匣安装边的激光修复工艺,解决原焊接方法导致焊后变形和裂纹难题,保证其使用可靠性。     

某型航空发动机高导外机匣内壁轴向裂纹故障分析及其工艺改进

针对某型航空发动机高压涡轮导向器外机匣多发轴向裂纹故障的问题,通过机匣工况分析和仿真建模,确定机匣裂纹部位的受力情况;通过金相显微镜观察裂纹宏观及微观形态,确定裂纹起始部位;通过扫描电镜和能谱分析了解断口表面腐蚀产物元素成分分析,最终确定裂纹性质为高温蠕变-腐蚀裂纹,并给出了后期的工艺改进方向。通过在裂纹多发部位喷涂热障涂层,降低基体温度和阻隔燃气,显著降低了故障率。     

镍基合金K4648焊接接头断裂韧度的研究

为了对某飞机发动机涡轮导向器叶片修复焊接后的安全性和寿命进行评估,试验研究了导向器叶片用K4648合金TIG焊接头的断裂韧度(K<,q>).分别测得了K4648合金母材、焊缝和热影响区的断裂韧度值,并对三个区域的显微组织特征进行了观察.结果表明:母材显微组织均匀,断裂韧度最高(59.17 MPa·m<'1/2>);热影响区因其晶粒粗大,断裂韧度较低(48.90 MPa·m<'1/2>);焊缝内由于是树枝晶组织,性能不均匀,加之存在气孔、夹渣等焊接缺陷,断裂韧度最低(48.11 MPa·m<'1/2>).     

感应钎焊修复PW4000发动机管件及其性能

对PW4000发动机4#轴承滑油压力管接头的钎焊工艺进行了研究,确定了合理的修复工艺参数。同时采用扫描电镜(SEM)和能谱分析等方法对钎焊接头界面组织进行了分析,并对接头界面组织进行了显微硬度测试。结果表明:通过采用该修复工艺,能够获得外观、密封性能和钎焊铺展率优良的接头,钎焊质量达到了PW4000发动机维修手册中的技术标准要求。     

高负荷运转下发动机高压涡轮盘材料断裂分析

采用微观、宏观和能谱分析方法研究高负荷机械运转下发动机高压涡轮盘FGH 4097粉末高温合金的断裂原因及机理。结果表明,发动机报废的主要原因是高压涡轮盘的疲劳断裂。夹杂物的主要组成是毛坯焊接过程中产生的焊渣,焊渣和合金发生化学反应生成PPB。     

Plasma transferred arc repair welding of the nickel-base superalloy IN-738LC

Plasma transferred arc welding (PTA) has been considered a promising process to restore worn areas of land-based gas turbine blades and vanes. The objective of this investigation was to study the effect of PTA welding on the repairing of IN-738LC superalloy components. Tensile tests were conducted on specimens welded with various combinations of parameters. Room temperature, 760 °C, and 980 °C were selected as tensile test temperatures. High-temperature phase transformed, during solidification, were identified by differential thermal analysis (DTA). The weld-pool shapes and microstructures of welded specimens prepared by various welding parameters were evaluated by optical metallography (OM), a scanning electron microscope (SEM) equipped with energy dispersive x-ray spectrometer (EDS), and microhardness testing. Results of this study showed that PTA welded specimens exhibited 96% nominal tensile strength of IN738LC base materials. Specimen failure was observed predominantly in the base materials instead of in the heat-affected zone (HAZ) for gas tungsten arc weld (GTAW) repair weldments. IN-738LC is considered susceptible to weld cracking during fusion welding; however, using a low-input heat repair welding process (PTA), cracking susceptibility could be minimized by the optimized welding parameters.     

秦山核电站320MW汽轮机静叶片裂纹的焊接修复

对秦山核电站320 MW汽轮机静叶裂纹产生的原因进行了分析,从母材的材质性能、裂纹倾向、焊接拘束及应力状态等方面,对静叶焊接修复的可行性进行了分析,针对马氏体不锈钢的焊接修复特点,分析了不同的焊接修复方案,制定了合理的修复焊接工艺,着重阐述了裂纹挖补、焊前预热、母材小热输入焊接、焊后热处理及焊后PT检查等一系列修复措施。     

数控机床滑动导轨耐磨涂层修复工艺技术

大型数控车床导轨之间一般采取耐磨涂层接触,使用时间过长后,耐磨层会出现磨损。详细介绍数控机床导轨修复工艺,包括材料选择、修复参数确定、修磨工艺技术方法,重点描述修复过程调整检测方法及要点,并简单阐述了此次维修的意义。     

智能化焊接CAPP的分析与开发

通过分析国内外焊接CAPP的研究现状和需求,提出了将焊接专家系统技术融入到焊接CAPP中,并成功开发了焊接领域第一个智能化CAPP系统. 通过焊接工艺设计模块、工艺过程卡编制模块、材料定额计算模块共同完成焊接工艺的编制. 其中焊接工艺设计模块建立了焊接知识库、焊接推理机、焊接工艺解释机制,使其能够自动推理焊接工艺参数;工艺过程卡编制模块提供了典型工艺编制法、相似工艺编制法和菜单编制法,使工艺人员能快速完成工艺编制;材料定额模块通过焊接坡口参数化和迭代思想实现了计算各层焊接材料消耗量及总用量.     

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.     

改善某机涡轮叶片荧光渗透检测背景过度的试验

荧光渗透检测某机高压涡轮叶片时,批量性出现荧光背景过度导致无法检测叶片的问题。采用理论和工艺试验相结合的方法,分析了荧光背景过度产生的原因,制定了有效的解决方法,较好地改善了该高压涡轮叶片的荧光背景。     

Recent developments in repair welding technologies in Japan

Abstract

Developments in some difficult repair welding technologies in Japan during the past decade are reviewed. The topics covered include the repair welding of bridges in service, the temper bead method which makes it possible to omit post-weld heat treatment (PWHT) of repaired pressure vessels, the seal welding of a reactor vessel in which stress corrosion cracks were detected, low heat input repair welding of neutron irradiated stainless steel and nickel based alloys, the prevention of solidification cracking in repair welding of aged heat resistant cast steels, the development of welding materials for the mending of single crystal nickel based superalloy turbine blades, underwater repair welding of nuclear reactors, the reduction of residual stresses in repair welding, and an ultrasonic testing method for nickel based weld metals. The local PWHT of creep resistant ferritic steel tubes is also reviewed.     

发动机涡轮叶片断裂故障分析

发动机在工作过程中突然停车,检查发现低压涡轮转子叶片全部损伤,高压涡轮叶片均齐根折断。通过对高低压涡轮叶片断口特征进行宏观检查分析,确定了首断件及其断裂性质为疲劳断裂;对首断件叶片断口进行显微分析,研究了断裂特征和疲劳扩展情况;断裂的原因为叶片上下缘板总间隙在使用过程中变大,阻尼效果变差,叶片异常振动,离心应力叠加振动应力,致使叶片在工作过程中断裂。     

水下高压局部干式自动焊接试验装置控制系统

研制了一套用于水下高压局部干式自动焊接试验控制系统。此试验系统采用液压作为动力源,可在由排水罩形成的局部干式空间内进行MIG焊接。此系统采用西门子PLC、压力传感器、行程开关、水下摆心传感器等作为其主要的控制部件。由焊接环境控制、液压驱动自动焊机控制和水下摄像三套子系统构成。此系统可以实现在高压有水环境下远程遥控的局部干式自动焊接。结果表明,此焊接试验装置工作稳定,水下焊接焊缝质量良好。这些研究工作为核电厂水下焊接维修奠定基础。