三偏心蝶阀等离子喷焊设备的研制

根据三偏心蝶阀喷焊的技术要求和等离子喷焊设备的发展趋势，研制出三偏心蝶阀自动跟踪等离子喷焊设备。主电路采用2台IGBT逆变焊机作为等离子喷焊主弧与维弧电源。控制系统采用双机控制，可编程控制（PLC）实现喷焊工艺控制，单片机80C196KC进行实时跟踪控制。设备性能测试和蝶阀喷焊结果表明：该设备设计合理、运行稳定、可靠．喷焊质量优良。     

PLC应用于三偏心蝶阀等离子喷焊系统的设计

三偏心蝶阀等离子喷焊不仅工艺过程复杂，并且涉及到单片机80C196KC为核心的跟踪系统，因此对控制系统的可靠性要求很高。采用可编程控制器（PLC）控制有助于提高三偏心蝶阀喷焊质量与系统稳定性。文中介绍了三偏心蝶阀及其等离子喷焊过程控制的要求、PLC的硬件系统设计与喷焊工艺软件程序设计。     

蝶阀等离子喷焊焊缝跟踪系统设计

针对蝶阀密封面等离子喷焊需要,在分析三偏心蝶阀焊缝轨迹和单片机控制特点的基础上,提出了焊缝跟踪系统方案.研究设计了控制系统的硬件及软件.详细说明了硬件组成和软件设计方法,给出了步进电机的转向、频率和运行步数、升降速度3个重要参数的控制算法,以及数据采集、接收、处理方法.提出了软件整体采用表格结构和模块化方法设计,以及使用MATLAB和汇编相结合的方法进行调试,实现三偏心蝶阀密封面实时跟踪的高质量喷焊.     

阀门密封面的钴基合金粉末等离子弧焊工艺

介绍了阀门密封面常用材料堆焊钴基合金粉末的化学成分、牌号类别和熔敷金属层常有的缺陷。通过理论分析、工艺参数制订和试验数据分析对等离子弧堆焊(PTA)工艺进行了研究,总结了三偏心蝶阀密封面堆焊钴基合金粉末等离子弧堆焊的质量控制措施。     

激光熔覆层与等离子喷焊层凝固组织对比及界面特征

通过对气门密封面等离子喷焊基体上进行激光熔覆处理试样的分析,探讨了等离子喷焊层与激光熔覆层的凝固组织特征以及界面区域组织变化.结果表明,在等离子喷焊层基体上生长起来的激光熔覆层的组织更加细小,两层之间呈冶金结合,具有明显的组织遗传性.通过该实验,从微观组织方面证明了对气门密封面进行激光熔覆修复的可行性.     

玻璃模具型腔等离子弧喷焊工艺试验

采用等离子弧喷焊工艺方法,选用镍基合金粉末在玻璃模具型腔的关键部位进行了等离子弧喷焊工艺试验,对喷焊层金属的显微组织进行了分析,测试了喷焊层的显微硬度.试验结果表明,喷焊层与基体为冶金结合,喷焊层呈枝状晶组织,硬度达到HV296.通过对玻璃模具型腔进行等离子弧喷焊镍基合金,玻璃模具的耐磨性、抗高温氧化性能得到显著提高,其使用寿命也得到延长.     

等离子喷焊工艺试验及其在热轧导卫板上的应用

应用合金粉末等离子喷焊技术进行工艺试验,获得了Fe50、Ni60及NiWC25三种优质合金强化喷焊层.热轧导卫板表面等离子喷焊NiWC25工业试验表明:具有NiWC25等离子喷焊强化层的Q235导卫板使用寿命高,平均过钢量达10万吨,约为灰铸铁HT200导卫板的5倍.     

粉末等离子弧喷焊

前言我厂生产的高温高压阀门、电站阀门及安全阀等,密封面均为高温硬质合金材料,采用手工填充丝氧炔焰堆焊、氩弧焊和手工电弧堆焊。由于硬质合金堆焊工艺性差、劳动强度大,有时堆焊产品的返修率较大,长期以来,一直是阀门生产中的一个薄弱环节。为了提高阀门密封面质量,实现机械化堆焊操作,1969年下半年,我们开始进行粉末等离子喷焊阀门密封面的试验,经过半年多的试验研究,逐步解决了一些技术关键问题,并于1970年上半年开始小批投入生产,使用效果很好。现将粉末等离子弧喷焊的设备、工艺、防护设施等介绍如下。     

Q235钢表面等离子喷焊钴基自熔性高温合金工艺分析

从模具、冶金行业机械设备的破坏实例发现,提高工件的耐磨、耐蚀性能是提高其寿命的重要途径之一,表面喷焊耐磨层是现阶段的研究重点.文中采用等离子喷焊工艺进行正交试验,在Q235钢表面制备了钴基自熔性高温合金耐磨层,并探究了喷焊层质能量与稀释率之间的关系.采用极差分析法探究焊接电流、喷焊速度和送粉流量三个典型喷焊工艺参数对喷焊层硬度、耐磨性和稀释率的影响规律,并对喷焊工艺进行优化.结果表明,优化后的最佳喷焊工艺为喷焊电流60 A,送粉流量23.5 g/min,喷焊速度80 mm/min.     

等离子弧堆焊Co121F(CoCr-E)合金焊粉在船用增压衬环上的应用

阐述了应用等离子弧堆焊工艺在船用增压衬环上堆焊Co121F(CoCr-E)合金焊粉的实验及应用过程。通过模拟产品的等离子堆焊工艺,确定了在衬环密封面上堆焊Co121F(CoCr-E)合金焊粉的可行性,采用合适的堆焊工艺参数指导生产。生产实践证明,堆焊后可满足对衬环的密封面耐热冲击、耐磨损、耐高温腐蚀合金层的设计要求。     

等离子喷焊过程的微机控制

采用IGBT逆变电源为喷焊电源的单电源供电方案,研制了以高性能单片机80C196KC为核心组成的自动等离子喷焊控制系统,实现了等离子喷焊设备的小型化、控制微机化和操作自动化.     

Microstructure and fatigue properties of plasma transferred arc alloying TiC-W-Cr on gray cast iron

In this paper, TiC-W-Cr powders were alloyed on grey cast iron by plasma transferred arc (PTA). The alloying samples were characterized the microstructure, microhardness, fatigue life and fatigue crack growth. From the results, it is indicated that two distinguishing region: alloying zone, heat affected zone are formed on the surface after PTA alloying. The alloying zone mainly consists of primary austenite, martensite, a eutectic of (Fe,Cr)₇C₃ carbide and austenite as well as the uniformly distributed un-melted TiC particles. PTA alloying TiC-W-Cr eliminates the stress concentration at the edge of graphite and produced hard carbide, resulting in frequent crack deflection. As a result, the Weibull distribution of fatigue life demonstrates that PTA alloying TiC-W-Cr exhibits longer lives compared to matrix and PTA hardening without reinforcement, but more scattered. In addition, on the basis of the careful observation of fatigue crack growth, it is shown that the fatigue crack growth rate could be retarded by PTA alloying TiC-W-Cr at low stress intensity.     

Predicting the dilution of plasma transferred arc hardfacing of stellite on carbon steel using response surface methodology

Control of dilution is important in hardfacing, where low dilution is typically desirable. At present, most fabrication industries use shielded metal are welding, gas metal arc welding, gas tungsten arc welding and submerged are welding processes for hardfacing purposes. In these processes, the percentage of the dilution level is higher, ranging between 10% and 30%. In Plasma Transferred Arc (PTA) hardfacing, a solidified metallurgical bond between the deposit and the substrate is obtained with minimum dilution (less than 10%). This paper highlights the application of response surface methodology to predict and optimize the percentage of the dilution of a cobalt-based hardfaced surface produced by the PTA process. Experiments were conducted based on a fully replicable five-factor, five-level central composite rotatable design and a mathematical model was developed using response surface methodology. Furthermore, the response surface methodology was used to optimize the process parameters that yield the lowest percentage of dilution.     

Hardfacing by plasma transfer arc process

The plasma powder transferred arc welding process which uses feed stock in a powder form has similarities with plasma wire transferred arc welding. This paper describes a comparative study of the two processes using a cobalt-based alloy commercially known as stellite 6. This Co-based alloy is recognized for its superior cavitation erosion resistance. The aim of this paper is to investigate the potential of plasma transferred arc coatings for the protection and refurbishment of hydraulic turbine blades. Coatings were evaluated for the influence of plasma gas flow rate on coating dilution, geometry, hardness and microstructure. Coatings processed with the atomized stellite 6 powder feedstock showed a superior surface quality, lower dilution, better wettability and wider tracks. This study provided new information about the refurbishing of worn hydraulic turbine blades, leading to a longer service working life.     

焊接工艺对2205双相不锈钢焊接接头综合性能的影响

采用等离子弧焊打底 TIG焊盖面及等离子弧焊打底 MIG焊盖面焊接工艺焊接了2205双相不锈钢,研究了2205双相不锈钢的焊接性,并对焊后固溶处理与未进行固溶处理的焊件组织特征、力学性能及抗腐蚀性进行了比较,研究了不同焊接热输入和固溶处理工艺对焊接接头综合性能的影响.     

Parameter optimization for tungsten carbide/Ni-based composite coating deposited by plasma transferred arc hardfacing

Ni-based composite coatings with a high content of tungsten carbides (Stelcar 65 composite coatings) were synthesized by plasma transferred arc (PTA) hardfacing. The welding parameters of Stelcar 65 composite coatings were optimized by orthogonal tests. The PTA welding parameters including welding current, powder feed rate and welding speed have significant influence on the tungsten carbide degradation. The values for the optimum welding current, powder feed rate and welding speed were determined to be 100 A, 25 g/min and 40 mm/min, respectively. The produced WC/Ni-based composite coatings were crack- and degradation-free. The microstructure of deposited layers, as well as the microstructure and microhardness of the optimal coating were further analyzed.     

硼对液压支架立柱等离子熔敷涂层组织性能的影响

使用自制药芯焊丝等离子熔敷技术在液压支架立柱表面制备高硼熔敷层,分别研究了硼对熔敷层显微组织、结构、显微硬度、耐磨性、耐蚀性的影响.结果表明,四组高硼熔敷层成形良好,无裂纹,组织均匀致密.随硼含量的增加,熔敷层的显微硬度先增加后降低,最大为440 HV20,耐磨性与硬度呈对应关系;盐雾试验480 h后1号,2号熔敷层未出现腐蚀点,表现出良好的耐蚀性.综合分析表明,B元素含量为1.150%时,在保证硬度和耐磨性能的同时,盐雾腐蚀480 h未出现腐蚀点,满足液压支架立柱的使用要求.     

Plasma transferred arc welding—modeling and experimental optimization

Plasma transferred arc (PTA) welded coatings are used to improve surface properties of mechanical parts. Advantages are the high reliability of the process and the low dilution of substrate and coating material. Processing of surfaces by PTA welding is restricted at the time to flat horizontal position. Furthermore, industry is interested in the development of strategies for coating with PTA in constraint position as complex three-dimensional (3D) parts could be then easily processed as well. Under commercial aspects, the process design can be optimized to increase process efficiency and to reduce heat input during the welding process. Process optimization involves the determination of guidelines for PTA welding in constraint positions as well. Modeling the process gives an alternative to reduce the experimental effort to optimize the welding process. Results of simulation studies of the PTA welding process are given in the present work. It will be shown that coating conditions can be optimized by varying plasma gas flow, heat input and heat flow, process speed, or powder injection with regard to welding in constraint positions. The defined controlling of the PTA welding allows modification of process management with less experimental effort and to develop coating strategies for processing in different positions. In experimental investigations, the developed coating strategies are confirmed by producing PTA coatings in constraint position as well as complex 3D parts. This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials Park, OH, 2006.     

Cavitation erosion resistance of deposits processed by plasma transferred arc weldingArticle based on a version presented at the XXXI CONSOLDA,São Paulo,Nov 29–Dec 1 2005.

This work sets out a development of the equipment and an evaluation of the process of powder fed transferred arc plasma welding (PTA powder) with an emphasis on its utilization in coating metallic surfaces out of a flat position. After analysing the possibility of using the process in refurbishing hydraulic turbines eroded by cavitation, an analysis was made of the performance of the process and of the influence of the type of current (constant direct current and pulsed direct current) on resistance to cavitation of Stellite 6 alloy in accordance with ASTM standard G-32/92, by the indirect method. From the Stellite 6 alloy coatings deposited by the PTA process – powder using constant direct current and pulsed direct current, no significant difference was observed in the resistance to cavitation. On the other hand, the resistance to cavitation of the Stellite 6 alloy coatings obtained by the PTA powder process showed a performance higher than that of the Cavitec alloy obtained with the MIG and wire fed PTA welding processes.