A flux-core wire for hardfacing sealing surfaces of stop valves

A new flux-cored wire producing the deposited metal of high-chromium steel of the Fe–Cr–Ni–Mo–Mn–Si–Nb–Ti–B alloying system is described. The structure of the deposited metal and the composition of the hardening phases are determined. The role of borides in increasing the wear resistance and stability of the properties of the metal in hardfacing is analysed.     

Hardening rolling rolls by hardfacing with an alloyed strip electrode under a ceramic flux

The composition of 20KhN4MFB coldrolled strip for hardfacing rolling rolls was determined and production started. The deposited layer is characterized by high impact toughness, plasticity and resistance to cyclic heat changes. Additional alloying to increase the hardness and wear resistance of the metal is carried out through a ceramic flux. The composition of the new ceramic flux is characterized by improved welding and technological properties and relatively low chemical activity. Hardfacing of the hot rolling rolls increases the volume of rolled material per 1 mm of the reduction of the roll diameter.     

钒对铁基碳化钨耐磨堆焊层组织和性能的影响

在自研制的碳化钨管状药芯焊条中添加不同含量的钒元素（0%~3%）并制备堆焊合金,通过SEM,XRD,EDS等研究分析手段,研究不同钒含量对碳化钨耐磨层组织性能的影响规律.结果表明,钒含量与堆焊层中碳化钨颗粒的溶解程度密切相关,钒优先将碳化钨颗粒分解出的碳原子以碳化钒形式固定,从而抑制了碳化钨颗粒的分解,钒元素含量决定了碳化钨溶解的强弱,含有2%钒元素的堆焊层中生成适量碳化钒有效抑制了碳化钨的溶解.钒元素的加入还能强化碳化钨堆焊层基体金属的硬度,降低堆焊层中碳化钨颗粒剥落的风险,有效提高了堆焊层的耐磨性.     

Fe-C-Mo-V堆焊合金的滚动三体磨粒磨损行为研究

通过熔化极气体保护焊技术制备了Fe-C-Mo-V堆焊合金磨损试样,基于滚动三体磨粒环境下进行了干砂橡胶轮磨损试验,利用扫描电子显微镜、能谱分析、维氏硬度计等显微分析和性能测试方法,对Fe-C-Mo-V堆焊合金熔敷金属的磨损失重和磨痕形貌进行检测与表征,研究了不同法向载荷条件下该熔敷金属的磨损行为变化规律.结果表明:随法...     

Development of new type of wear and crack resistant hardfacing electrode

By using H08A bare electrode and the coating fluxes of ferrotitanium, rutile, graphite, calcium carbonate and calcium fluoride, a new type of wear and crack resistant hardfacing electrode was developed. The microstructure and wear properties of deposited layer were studied by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry(XRD) and wear test. The results indicate that TiC particles are produced by direct metallurgical reaction between ferrotitanium or rutile and graphite during welding process. TiC particles with sizes in the range of 3 - 5μm are dispersed in the matrix of lath martensite and retained austenite. The deposited layer of the new type of hardfacing electrode possesses better wear and crack resistance than that of D618 and D667 hardfacing electrodes.     

Microstructures and properties of non-preheated hardfacing welding

A new type of non-preheated hardfacing electrode was developed using H08A as the core and the coat contents including ferrotitaninm, ferrovanadium, graphite, rutile etc. The microstrnctures and properties of hardfacing metal were systematically researched. The results show the hardness of hardfacing metal increases with increasing of ferrotitanium, ferrovanadium, graphite in the coat, but the crack resistance and processing weldability become worse. The carbides formed by arc metallurgic reaction are uniformly dispersed in the matrix structure. The phases of hardfacing metal consist of α-Fe, γ-Fe, VC, TiC and Fe3 C.The carbides are compression aggregation of TiC and VC, and their appearances present irregular block. The matrix microstrncture of hardfacing metal is lath martensite. The hardfacing layers with better crack resistance and wearability are achieved and no visible cracks occur when using non-preheated electrode in continuous welding process. Hardness of hardfacing metal is more than 60HRC, and its relative wearability is five times of wearability of D667 electrode in abrasive wear test.     

镍基高温耐磨无渣堆焊焊条及其热处理工艺

针对镍基合金具有优良的高温综合性能,且目前市场上几乎没有这类手工电弧堆焊材料等实际情况,研制开发了一种抗高温耐磨损的镍基无渣堆焊焊条.该焊条具有焊接烟尘小,烟尘中含对人体有害气体极少;焊后焊道上几乎没有熔渣,连续多层焊无需敲渣;价格便宜(与钴基合金相比),高温(650℃左右)性能优良等特点.此外,该焊条由于熔敷金属中含合金元素量较一般堆焊焊条的熔敷金属多,成分复杂,焊后焊缝中存在的内应力较大,且焊缝在快速冷却条件下产生的组织不稳定,从而影响到熔敷金属的综合性能.为了能更好地推广和更合理地应用这种高温无渣耐磨堆焊焊条,对其熔敷金属的热处理工艺也进行了初步探讨.     

1Cr13NbTi不锈钢堆焊材料氮合金化分析

用氮代替部分碳,通过铌、钛固氮形成氮合金化1Cr13NbTi堆焊合金,深入分析了碳氮化物的形成机理,进行了耐磨粒磨损性能试验,研究了碳氮化物对堆焊合金耐磨粒磨损行为的影响.结果表明,堆焊合金中的碳氮化物为分布在晶界和晶内的MX（M=Nb,Ti;X=C,N）复合型碳氮化物.焊态和热处理条件下具有不同的数量和尺寸,初生的碳氮化物在焊缝凝固过程中形成并具有较大尺寸,数量较小;大量的细小二次碳氮析出物能在热处理后大量弥散析出,对基体产生明显的沉淀强化作用,在增强堆焊合金硬度减小磨粒锲入深度的同时有效阻碍磨粒的切削,从而获得高的耐磨粒磨损性能.     

ZA27合金气焊接头耐磨性能的研究

对不同载荷作用下，用ＺＡＢ、ＺＡ１２、和ＺＡ２７焊丝气焊的ＺＡ２７合金接头熔数金属的耐磨性能进行了研究。结果表明，随熔敷金属中Ａ１含量增加，载荷降低，耐磨性提高。     

Submerged-arc hardfacing large components with a composite strip electrode

Results of investigations and development of the highly productive technology of submerged-arc large components with a composite strip electrode are presented. It is shown that selecting the optimum dimensions of the composite strip electrode and the welding conditions ensures high quality of formation of the bead in depositing the sub-layer and the wear-resisting layer.     

高硬度高耐磨自保护金属芯堆焊焊丝

研制一种焊接工艺性能良好的高铬铸铁型自保护金属芯堆焊焊丝,堆焊层硬度大于60HRC,耐磨性为Q235钢的21倍.对其自保护机理进行了研究,当粉芯中金属Mn含量达到5%时,可保证焊缝表面不出现气孔,当钛铁含量超过10%时,焊缝表面出现压坑.堆焊层显微组织为马氏体 残余奥氏体,在马氏体基体上均匀分布着M7C3型耐磨硬质相.     

Fe-Cr-C耐磨堆焊合金磨粒磨损行为

采用埋弧堆焊方法,在Q235钢表面制备Fe-Cr-C耐磨合金,在MLS—225型湿式橡胶轮磨粒磨损试验机上进行磨粒磨损试验,通过对磨损试样表面的扫描电子显微镜观察分析并结合能谱成分分析研究磨损形成机制.结果表明,Fe-Cr-C耐磨堆焊合金在试验的湿石英砂磨料磨损条件下,磨损机制以微裂纹引起的剥落去除机制为主,也存在一定数量的犁沟或犁皱造成的微切削去除机制.剥落的发生与碳化物密切相关,能谱成分分析表明剥落坑内Cr元素含量对应在(Cr,Fe)7C3铬含量范围内,说明剥落坑是碳化物断裂造成的.     

铁基堆焊耐磨合金的研究现状

概述耐磨堆焊材料、方法的分类及堆焊层合金元素的性质和堆焊层中碳化物形成特点;对铁基堆焊耐磨合金的固溶强化、第二相强化(弥散强化和析出强化)、晶界强化、热处理和定向凝固等强化方法进行了论述。分析合金元素在堆焊层中的作用、磨料磨损的形貌以及铁基耐磨合金的耐磨机理。铁基堆焊具有成本低、品种多,且易于改变堆焊层强度、韧性、耐磨性、抗冲击性等优点。铁基堆焊耐磨合金是当前研究的重要方向之一,应用前景广阔。     

Evaluation of mass loss of weld-deposited hardfacing with cored wire Ti-FeCrC alloy

In this article, we have studied the mass loss of hardfacing applied by flux-cored arc welding. Heat input, shielding gas and number of layers of coating were changed to application of Fe–Cr–Ti–C self-shielded tubular wire. Overlapping beads were deposited on plates of carbon steel AISI 1020 to analyse the mass loss, hardness and microstructure. For the analysis of mass loss, beads were deposited forming overlapping layers of coatings. Hardness measurements were performed on the surface of the specimens of wear. A rubber wheel abrasion tester was used to access the mass loss of coatings. The coatings had retained austenite and martensite microstructure with carbides finely dispersed in the matrix. The main factors that contributed to the increase in mass loss were the cracks due to higher cooling rate of the samples deposited with low heat input, the dilution in the first layer of all samples also contributed to the increase in mass loss. The smallest mass losses were those deposited coatings with high heat input, the second and fourth layers, the samples AC2, AC4 and AS2. The volume fraction of titanium carbides contributed to the decrease in the mean free path between the particles of carbides and increased the wear resistance of the coatings.     

D256耐磨堆焊接头组织与性能

采用D256耐磨焊条在Q235A钢基体上进行堆焊,研究不同焊接电流下D256堆焊接头组织和性能的变化。试验结果表明:采用D256耐磨焊条堆焊时,焊缝组织为奥氏体和渗碳体,电流较小时,焊缝组织是过饱和奥氏体,随着电流的增大,奥氏体晶粒增大,合金元素溶入,焊缝的硬度与耐磨性均降低。电流增大到140 A时,焊缝中的奥氏体晶粒最大,合金充分溶入奥氏体中,使得焊缝的硬度和耐磨性最低。电流较小时,焊接接头过热区的组织主要是晶粒较粗大铁素体、珠光体和魏氏组织的混合物,电流增大,晶粒增大,在电流140 A时过热区为粗大且明显的魏氏组织。正火区为比母材细小的铁素体和珠光体,堆焊层未出现裂纹,熔合良好,堆焊接头焊缝与HAZ硬度均高于母材,在100 A电流下得到组织和耐磨性能优良的堆焊层。     

TD盐浴渗钒覆层的耐磨性研究

通过硬度测试和磨损试验,研究了碳化钒覆层前后Cr12MoV表面的硬度和耐磨性的变化,分析了表面覆层磨损机制。结果表明,硬度和耐磨性均有明显提高,其磨损机制为疲劳剥落磨损。     

钒对Fe-Cr-C耐磨堆焊层性能的影响

在Fe-Cr-C耐磨堆焊合金中加入钒,研究钒对Fe-Cr-C耐磨堆焊合金焊态和焊后热处理态性能的影响.采用埋弧堆焊方法在Q235低碳钢基体上制备了堆焊层,利用光学金相、SEM分析了堆焊合金的显微组织,并进行了硬度和磨料磨损试验.结果表明,焊后加热对Fe-Cr-C耐磨堆焊合金的硬度有较大影响.经过焊后加热,基体组织的硬度降低值都大于22%,降低值最大的是不含钒的Fe-Cr-C耐磨堆焊合金,达到37.7%.焊后加热对初生碳化物M7C3的硬度影响较小,其硬度降低值为1.4%～11.3%.含0.4%V可以有效的提高Fe-Cr-C耐磨堆焊合金高温热处理后的耐磨料磨损性能.以淬火态的45钢为标样,在经过900℃焊后热处理,含0.4%V的Fe-Cr-C耐磨堆焊合金相对耐磨性为1.9,而同样条件下不含钒的试样相对耐磨性只有1.3,两者相比,含0.4%V的合金相对耐磨性提高了46%.     

热轧辊耐磨堆焊焊条的研究

研究了一种用于热轧辊堆焊的耐磨堆焊焊条，通过堆焊层的金相显微分析及Ｘ射线物相分析表明，其焊合金组织为马氏体＋残余奥氏体＋碳化物。堆焊层的硬度在ＨＲＣ５８￣６０之间，仍保持在ＨＲＣ５８￣５９，高应力磨粒磨损实验和工业试验证明，热轧辊堆焊合金的耐磨性优良是４５钢的６．１倍。     

A comparison of material removal mechanism under low stress abrasive condition of steel and hardfacing alloys

The low stress abrasive wear behavior of two types of steels commonly used for making a number of commonly used engineering components has been compared with the composition of a few hardfacing alloys that can be overlayed on the steels to impart a wear-resistant surface. The mechanism of material removal as studied by the scanning electron micrographs of the worn and transverse sections is different for the steels and hardfacing alloys. An attempt has been made to explain the mechanism of material removal for the steels and hardfacing alloys.