耐蚀堆焊层腐蚀磨损性能

用自制的腐蚀磨损试验机对耐蚀堆焊层在不同介质中的腐蚀磨损性能进行了试验，结果表明：腐蚀介质不同，堆焊层的磨损速率也不同。在酸性与中性介质中，奥氏体焊条堆焊层具有相对优良的耐腐蚀磨损性能，而在碱性介质中，低碳钢焊条堆焊层具有较高的腐蚀磨损抗力。另外，堆焊电流增大，有利于提高堆焊层的耐磨性。     

含稀土氧化物的WC-TiC-TaC-Co/CuZnNi复合耐磨堆焊材料

以WC-TiC-TaC—Co硬质合金、CuZnNi及氧化物La2O3为原料，研制出一种具有高耐磨性和良好抗冲击性能的堆焊材料，利用SEM、TEM、摩擦磨损试验分析了堆焊材料的组织及耐磨性，探讨了稀土氧化物对堆焊材料组织性能的影响．研究结果表明：硬质合金与Cu基合金通过元素扩散形成连接界面；堆焊层耐磨性随硬质合金含量的增加而增加，随载荷的增加而降低；加入La2O3后，基体组织细化，硬质合金与基体的界面上形成微晶过渡区，改善了界面结合强度，堆焊层耐磨性得到提高。     

堆焊层数对热丝脉冲TIG堆焊Inconel 625的腐蚀性能研究

为了研究热丝脉冲TIG(惰性气体钨极保护焊)堆焊不同层数Inconel 625后堆焊层的腐蚀性能差异,在20钢基体表面分别堆焊单层和双层Inconel 625,通过电化学试验、晶间腐蚀试验和EDS成分分析,对不同层数堆焊层的腐蚀性能进行了对比分析。结果表明：其bode谱中双层堆焊的相位角为80°,单层堆焊和基材的相位角分别下降5°和20°,双层堆焊的阻抗模量与频率的斜率最大,其次是单层堆焊的,基材的最小;基材的容抗弧最小且存在Warbug扩散,双层堆焊的容抗弧最大,单层和双层堆焊较基材的自腐蚀电位分别提高了374.0 mV和392.0 mV,腐蚀电流密度分别下降约99.3%和99.8%,双层堆焊的点蚀电位较单层的提高了430 mV。晶间腐蚀试验后,堆焊层均未出现明显晶间腐蚀而表现为点蚀,双层堆焊的腐蚀失重约为单层的1/5,腐蚀沿柱状晶间贯穿。堆焊层间融合区以及与基体交界处的合金元素变化显著,层内分布均匀,双层堆焊的Fe元素含量低于单层堆焊的,具有更好的耐腐蚀性能。     

Q345B钢堆焊层组织及性能研究

本课题以低合金高强度钢Q345B为基体,采用熔化极气体保护焊方法进行堆焊,采用金相显微镜、扫描电镜等检测手段,研究不同堆焊层数下的堆焊层及热影响区的组织、形貌、成分及硬度的变化。试验结果表明,堆焊层组织主要为铁素体和珠光体,从靠近母材的堆焊层到外部堆焊层的珠光体含量逐渐增加,堆焊层的硬度也逐渐增加。     

等离子弧堆焊复合粉末成分优化设计

为研制新型高温耐磨镍基堆焊合金粉末,采用等离子弧堆焊技术,在Q235钢表面制备了不同配比的镍基复合粉末堆焊层.以堆焊层表面硬度值为正交试验指标,利用正交设计及正交多项式回归分析对复合粉末进行优化设计.利用MM-200型环-块磨损试验机对不同成分的堆焊层进行磨损试验.结果表明,当镍基基础粉末中添加的强化元素配比为10%Cr,4%Mn,7% W时,该复合粉末堆焊的试件耐磨性能较采用基础粉末的堆焊层提高约10倍.实践表明,本研究优化了设计,提高了复合粉末堆焊层的性能.     

无塑性转变温度（NDTT）实质的探讨

通过１６Ｍｎ钢落锤试样在系列温度下的静载弯曲试验，发现其断裂行为与脆性堆焊焊道及热影响区的存在无关，用于做静态三点弯曲试验的落锤试样表面出与母材相同的冷脆转变特性。落锤试样的堆焊焊道相当于对试样引入一个动态缝。文中提出，ＮＤＴＴ实质是在支载条件下材料冷脆特征温度的反映，若对ＮＤＴＴ做为设计指标，则偏于安全。     

镍基合金粉末光束堆焊层的微观组织及强化机理

采用X射线衍射，SEM，EDAX及显微硬度和洛氏硬度等分析手段研究了含碳量为1．0％的NiCrBSi系自熔合金粉末光束堆焊层的微观组织及强化机理，结果表明，采用光束镍基合金粉末堆焊可在铁碳合金表面获得与基体冶金结合良好，无裂纹，轻度稀释的强化层，堆焊热输入对堆焊层稀释率及合金元素烧损的影响程度决定了堆焊层微观组织及物相组成，小热输入堆焊时，堆焊金属经度稀释（η=3.5%），其显微组织由少量初生的γ－Ni和大量的γ－Ni Bi3B Ni3Si三相共晶组成的亚共晶基底，以及在基底上分布着大量的Cr23C6,(Cr,Fe)7C3高硬度相组成，采用大热输入堆焊，堆焊金属稀释率达12％，堆焊层由大量的γ－（Fe,Ni0枝晶和少量γ－(Fe,Ni) M7C3共晶组成，在堆焊层中未发现一次碳化物的析出，在光束粉末堆焊层中大量高硬度M23C6,M7C3共晶组成，在堆焊层中未发现一次碳化物的析出，在光束粉末堆焊层中大量高硬度M23C6，M7C3型碳化物和Ni3B,Ni3Si共晶相的析出以及合金元素在γ相中的过饱和固溶是其是以强化的主要原因，与TIG堆焊相比，采用相近热输入所获得的光束粉末堆焊层的耐磨性能提高了3倍以上。     

铬镍奥氏体不锈钢材料的堆焊工艺研究

对15CrMoR板采用了不同焊接工艺进行堆焊试验分析研究,结果显示,若不加过渡层E309L,只用E347L焊条在15CrMoR板上堆焊是不合理的。     

过渡合金层对激光多层堆焊组织性能影响

采用45钢作为基体材料,在不预热情况下通过增加过渡合金粉堆焊层,再选用专用焊丝进行堆焊试验。由于过渡合金粉中的Ni、Cr提高的奥氏体的稳定性,产生FeNi缓解了高硬度焊丝中碳化物内产生的残余应力,多次堆焊加热使其热应力在该区域得到缓解,减少了裂纹倾向,同时焊丝中的C、V等形成碳化物,因此提高了堆焊层的硬度。     

不锈钢堆焊过渡区显微组织对氢致剥离的影响

通过一系列电解充氢试验比较了不同焊后热处理条件对不锈钢堆焊层氢致剥离的影响。结果显示,提高焊后热处理参数,熔合线堆焊层侧增碳层宽度增加,氢致剥离的倾向也增大。利用金相显微镜和微区分析的手段,研究了不锈钢堆焊层过渡区显微组织及其对堆焊层氢致剥离的影响。研究表明,经过焊后热处理,堆焊过渡区中碳、铬元素均有迁移。在氯致剥离裂纹产生的区域,碳和合金元素分布发生突变。     

Research About Microstructure and Wear Resistance of Hardfacing Layer on Cast Iron

It's simple technology to manufacture big trimming die by hardfacing on the base metal of cast iron. The chemical composition, microstructure, hardness, wear resistance and wear mechanism of the hardfacing layer were studied.The experimental results indicate that the hardfacing technology has much more advantages and cheaper than that of traditional process. The chemical composition, microstructure, hardness of the hardfacing metal are all satisfied for manufacturing the big trimming die by welding on cast iron. The wear resistant test of hardfacing layers were carried out by using two different electrodes. The wear resistance of new electrode hardfacing layer is higher than that of normal hardfacing electrode D322. The wear mechanism of hardfacing layer is belongs to abrasive wear model.     

TiC-VC耐磨堆焊焊条

利用药皮中的石墨、钛铁、钒铁、金红石等组分,通过电弧冶金反应生成了具有高显微硬度的TiC、VC等碳化物,探讨了焊条药皮组分石墨、钛铁、钒铁等的含量对焊条工艺性、抗裂性及堆焊层硬度的影响,利用X射线衍射、扫描电镜（SEM）和电子探针（EMPA）对堆焊层显微组织,TiC、VC等碳化物的分布以及断口形貌进行了分析。研究结果表明,堆焊层组织为低碳马氏体＋残余奥氏体＋碳化物,碳化物极弥散分布在低碳马氏体基体上,断口为准解理断裂;堆焊层具有较高塑韧性,焊前不预热,焊后不缓冷连续堆焊不产生裂纹;堆焊层硬度达到HRC55以上,具有高的耐磨性,相对耐磨性优于D667焊条。     

高铬铁基药芯焊丝不同堆焊工艺下的显微组织与性能研究

采用高铬铁基耐磨合金细粉做成药芯焊丝,分别用埋弧堆焊和等离子束堆焊方法制备耐磨试样,对试样的显微组织、硬度分布、耐磨性分别进行研究。实验表明：埋弧堆焊和等离子束堆焊组织具有较明显的区别,埋弧堆焊试样结晶定向性更好,晶粒更细化;埋弧堆焊涂层显微硬度平均值为791 HV0.2,等离子束堆焊涂层显微硬度平均值为774HV0.2,埋弧堆焊涂层的显微硬度分布更均匀;耐干砂磨粒磨损性能埋弧堆焊是等离子束堆焊的1.7倍。     

Enhancement of ballistic capabilities of soft welds through hardfacing

An attempt has been made to improve the ballistic immunity of austenitic welds through a hardfacing technique by a shielded metal arc welding process. Welds with complete hardfacing shattered under ballistic impact. An overlay of hardfacing alloy over austenitic weld disintegrated due to extensive cracking in the hardfacing layer. Sandwiching of the hardfacing alloy weld between austenitic welds served the dual purpose of weld integrity and ballistic immunity due to the high hardness of hardfacing alloy and the energy absorbing capacity of austenitic weld deposit. However, for full ballistic immunity equivalent to the base metal a minimum thickness of hardfacing weld layer was found to be essential. The observed trends are explained on the basis of microstructural features and cracking behaviour in the hardfacing alloy.     

Microstructure and properties of the TiC/Fe-based alloy hardfacing layers

TiC/Fe-based alloy hardfacing layers were obtained by shielded metal arc welding (SMAW), in which H08A bare electrode was coated with a powder mixture of ferrotitanium, rutile, graphite, calcium carbonate and calcium fluoride. TiC particles are produced by direct metallurgical reaction between ferrotitanium and graphite during welding. The particles of TiC with cubic shape are distributed evenly in the Fe-rich matrix in the hardfacing layers, the particle size is about 3–5 μ m. The microstructure and mechanical properties of the hardfacing layers are markedly affected by the amounted of the ferrotitanium and graphite in the coating of the electrode. The wear properties of the hardfacing layers are superior to the substrate AISI 1045 steel. The coefficient of friction data of the hardfacing layers do not show significant fluctuations.     

硼对Fe-Cr-C耐磨堆焊合金组织的影响

在Fe-Cr-C耐磨堆焊合金中,加入硼元素可以有效地提高堆焊层的硬度。本工作以高碳、高铬耐磨堆焊合金为基础,在五组不同的堆焊焊条药皮中加入不同含量的硼元素,研究了硼对Fe-Cr-C耐磨堆焊合金硬度、组织的影响。实验结果表明,在Fe-Cr-C系耐磨堆焊合金中加入硼,当在0.1%～0.9%时,堆焊层表面宏观硬度随着硼含量的增加而近似的呈线性增加。当硼含量大于1%时,继续加入硼,对宏观硬度的增加影响较小。当含硼量在0.1%～0.9%范围内,硼能显著提高Fe-Cr-C耐磨合金组织中的硬质相密度。硼对硬质相密度影响的敏感成分范围是0.1%～0.9%,当硼含量大于1%时,继续增加硼含量,硬质相含量没有明显增加。在所研究的含硼量范围内,硼对基体组织的硬度影响较小。     

Hardfacing of Wear-Resistant Deposits by MAG Welding with a Flux-Cored Wire Having Graphite in Its Filling

A high carbon content in a ledeburite-martensite deposit provides high wear resistance. This can be accomplished in hardfacing by MAG welding with covered electrodes, alloying fluxes, and flux-cored wires. Hardfacing with covered electrodes is not efficient, whereas application of alloying fluxes is suitable only for the flat welding position. Hardfacing by flux-cored MAG welding, however, is efficient and suitable also for out-of-position welding, i.e., in the horizontal-vertical and overhead positions, which is particularly important in maintenance. The paper deals with the investigations of the influence of hardfacing-weld alloying by means of the cored-wire filling in hardfacing both by CO₂ welding and welding with no externally supplied shielding medium. The efficiency of alloying the hardfacing weld depended on the composition and the filling ratio of the wire. In hardfacing of martensite-ledeburite deposits, the high carbon content in the deposit was provided by the addition of graphite to the cored-wire filling. A result of the high graphite content in the filling was a reduction of the filling ratio of the wire, and, consequently, weaker alloying of the hardfacing weld. As little as 10 wt.% graphite in the wire filling substantially affects alloying of the hardfacing weld. In this case, the amount of carbide-forming elements in the hardfacing weld will be reduced by around 4 wt.% whereas the carbon content will increase by as little as 1%, which, however, is enough to obtain high-quality martensite-ledeburite wear-resistant deposits with S-BC3 cored wires and with no externally supplied shielding medium of which the chemical composition, structure, and wear resistance were quite comparable to those obtained with a CrWC 600 covered wire (produced by SZ-Elektrode, Jesenice). Advantages of the cored wire over the covered electrode are substantially higher performance and lower consumption of the electric current.     

Fe–15 wt-%Cr–X wt-%C hardfacing surface layer: wear resistance and its enhanced mechanism with C additive

Abstract

An electrode with different C additives was developed. The microstructure of the hardfacing surface layer was observed by optical microscopy. The phase structure was determined by X-ray diffraction. The hardness and wear resistance of the hardfacing surface layer were measured respectively. The worn-out surface and three-dimensional morphology were observed by field emission scanning electron microscope equipped with energy dispersive X-ray spectrometry. The relation curve between mass fraction of M₇C₃ carbide and temperature was calculated according to thermodynamics software Thermo-Calc. The results show that, with the increase in C additive, the hardfacing surface layer changes from a hypoeutectic structure to a hypereutectic one. Meanwhile, the primary phase changes from austenite to carbide. The hardness and wear resistance of the hardfacing surface layer increase gradually with the increase in C additive, and when the C additive is 25 wt-%, they are the largest. With the increase in C content, the precipitation temperature of M₇C₃ decreases from 1280 to 1260°C, while the maximum amount of M₇C₃ increases instead, which is from 0·154 to 0·313. The reason of the improvement for wear resistance of the hardfacing surface layer is that the carbide initiates and the amount of M₇C₃ increases.     

Metallurgical and Tribological Evaluation of Fe-Cr-C Hardfacing Alloys

Raw material handling areas in an integrated steel plant experience severe wear of engineering components. The use of hardfacing plates is one of the ways to combat this problem. Three commercial hardfacing Fe-Cr-C alloys of varying Cr content were deposited on mild steel base plate and studied in this work. Abrasive wear tests were conducted by using pin-on-disk tribometer in accordance with the ASTM G99. Microstructural characterization was done by using optical and scanning electron microscopes. Energy- and wavelength-dispersive spectroscopies were carried out to study the carbide type and distribution in the hardfaced deposit. It was observed that wear resistance increases with increasing Cr content in the alloy. Along with hardness, morphology and type of carbide are also important factors to decide the wear resistance. An attempt has been made to corelate the chemical composition, carbide morphology, and macrostructural features with wear properties of hardfacing alloys.     

硬面药芯焊丝材料的新进展

综述了硬面药芯焊丝研究的最新进展,对硬面药芯焊丝材料进行了分类,探讨了硬面药芯焊丝硬面层金属的合金类型和显微组织,指出了未来研究的主要方向.