两种硬面药芯焊丝堆焊层金属耐磨性的研究

对研制的两种硬面药芯焊丝HDY704、HDY502焊态和焊后热处理堆焊层金属的显微组织及耐磨性能进行了研究,探讨了堆焊层金属的磨损机理。结果表明：合金钢硬面药芯焊丝HDY704和不锈钢硬面药芯焊丝HDY502堆焊层金属的显微组织均为马氏体加少量残余奥氏体;焊后热处理均能提高其耐磨性能;热处理后HDY502堆焊层金属有弥散碳化物析出使硬度增加近10HRC,而HDY704堆焊层金属的硬度不变;堆焊层金属的磨损机理为沙粒在压力作用下被压入基体中沿运动方向的切削破坏。     

添加微量元素对多元复合强化高锰钢堆焊合金焊丝性能的影响分析

以直径为5 mm的多元复合强化高锰钢合金焊丝为研究对象,探讨了合金元素Cr、Mo、V等对堆焊合金焊丝熔敷金属组织与硬度和耐磨性能的影响。经多次对比试验,确定了多元复合强化高锰钢堆焊合金焊丝化学成分,该试验结果对进一步提高高锰钢的抗冲击耐磨性能及加工硬化能力提供了一定的参考。     

氮碳合金化自保护硬面药芯焊丝堆焊层的组织与性能

研制出了氮碳合金化自保护硬面药芯焊丝,探讨了回火温度对氮碳合金化自保护硬面药芯焊丝堆焊层硬度和耐磨性能的影响.结果表明:其堆焊层硬度为36.5～45.5 HRC,显微组织为板条马氏体和铬、钛、钒、铌的氮碳化物的复合物,堆焊层中的氮碳化物质点不易分解,有良好的稳定性和抗高温回火性能;回火温度为550 ℃时,堆焊层硬度达到最大值,回火温度高于550 ℃,硬度值基本保持不变;氮碳合金化自保护硬面药芯焊丝堆焊层金属的磨损机理为磨粒切削后塑性磨痕和氮碳化物的块状剥离,堆焊层具有良好耐磨性能的最佳回火温度为480～520 ℃.     

低温高韧性药芯焊丝性能试验研究

对国产药芯焊丝YJS07和YJS02进行了焊接工艺试验，观察了药芯焊丝熔敷金属的显微组织，分析了药芯焊丝的熔敷金属化学成分。进行了药芯焊丝所焊焊接接头的低温冲击试验及焊接接头的常温拉伸试验。结果表明，国产药芯焊丝YJS07和YJS02具有良好的焊接工艺性能，其熔敷金属扩散氢含量较低；YJ507药芯焊丝的熔敷金属中含有一定量的镍，细化了先共析铁素体，提高了其低温韧性；YJS02药芯焊丝的熔敷金属含有一定量的钛和硼，易于形成针状铁素体，从而提高其低温韧性。     

低温高韧性药芯焊丝性能试验研究

对国产药芯焊丝 YJ5 0 7和 YJ5 0 2进行了焊接工艺试验 ,观察了药芯焊丝熔敷金属的显微组织 ,分析了药芯焊丝的熔敷金属化学成分。进行了药芯焊丝所焊焊接接头的低温冲击试验及焊接接头的常温拉伸试验。结果表明 ,国产药芯焊丝 YJ5 0 7和 YJ5 0 2具有良好的焊接工艺性能 ,其熔敷金属扩散氢含量较低 ;YJ5 0 7药芯焊丝的熔敷金属中含有一定量的镍 ,细化了先共析铁素体 ,提高了其低温韧性 ;YJ5 0 2药芯焊丝的熔敷金属含有一定量的钛和硼 ,易于形成针状铁素体 ,从而提高其低温韧性。     

钛和锆元素对自保护药芯焊丝熔敷金属组织和力学性能的影响

在自行研制的锰-镍-钼-铬系自保护药芯焊丝化学成分的基础上同时加入质量分数分别为0.09%和0.045%的钛和锆元素研制出一种新型焊丝,采用该焊丝以及未加入钛、锆元素的焊丝对Q235钢进行焊接试验,研究了钛和锆元素对熔敷金属显微组织和力学性能的影响,并对钛和锆元素的作用机理进行了讨论。结果表明:加入微合金元素钛和锆后,熔敷金属的组织更细小,针状铁素体含量更多,但硬度变化不大,抗拉强度和伸长率较未加入微合金元素的分别提高了7%和13%,-20℃冲击韧性提高了1.42倍;微量钛元素的加入能够起到脱氧、脱氮和促进针状铁素体形核的作用;微量锆元素的加入能够起到脱氧和细化组织的作用。     

D207堆焊工艺及性能研究

采用D207焊条用手工电弧焊在45号钢基体材料上进行堆焊试验,对堆焊层的金相显微组织进行了分析,对堆焊熔敷金属的硬度和磨损性能进行了测试。结果表明：采用D207焊条堆焊后,其熔敷金属层的硬度与耐磨性能均高于基体材料,大大提升了基体材料的各项性能,可用于45号钢零部件的修复。     

K360耐磨钢堆焊合金层的组织与性能

利用药芯焊丝对已磨损的K360耐磨钢进行CO2气体保护堆焊修复,并对堆焊层进行了显微组织、X射线衍射、硬度、冲击韧度及抗磨料磨损性能试验.结果表明:堆焊层的组织为细小板条马氏体 少量弥散分布碳化物,硬度不高,产生冷裂纹倾向小,韧性与塑性较高;同时堆焊层组织细小,弥散分布的碳化物对焊层基体有强化作用,使堆焊层的耐磨性达到了基体的水平.     

钛型渣系气保护药芯焊丝熔敷金属力学性能的控制

本文从熔敷金属的化学成分、显微组织形态，力学性能的联系及主要技术指标等方面。探讨了钛型渣系气保护药芯焊丝熔敷金属力学性能的控制机理。结果表明，该焊丝的化学成分受熔敷金属力学性能要求的制约，不仅要控制单个元素在一个较小的范围。而且应当顾及有关元素之间适当的比例关系。获得理想细晶粒针状铁素体组织的冶金学途径有：控制硅、锰比，加入钛、硼微量元素。加入稀土元素等。关键技术是找出添加物与显微组织之间的定量关系。用户对焊丝熔敷金属力学性能指标的要求较严，必须综合控制成分，组织，工艺等及其影响因素，以获得稳定的试件抗拉强度，屈强比和低温冲击吸收功等力学性能指标。     

两种模具堆焊修复用药芯焊丝堆焊金属的性能对比

对两种商用模具堆焊修复用药芯焊丝堆焊金属进行了硬度及冲击韧性对比试验,分析了性能产生差异的原因.结果表明:525焊丝堆焊金属的硬度及冲击韧性均高于136焊丝堆焊金属的;两种焊丝堆焊金属基体组织均由马氏体、贝氏体和铁素体组成,但525焊丝堆焊金属的晶粒尺寸较小,堆焊金属冲击断口的纤维区面积较大,韧窝更小、更多;两者韧性存...     

The Influence of the Matrix Microstructure on Abrasive Wear Resistance of Heat-Treated Fe–32Cr–4.5C wt% Hardfacing Alloy

The abrasion wear resistance of Fe–32Cr–4.5C wt% hardfacing alloy was investigated as a function of matrix microstructure. In this study, the alloy was deposited on ASTM A36 carbon steel plates by the shielded metal arc welding (SMAW) process and the as-welded matrix microstructure was changed into ferrite, martensite, and tempered martensite by heat treatment processes. The Pin-on-disk test results show that under low (5 N) and high (20 N) load conditions, the wear resistance behavior of the as-welded matrix sample is 20 and 15% higher, respectively, than the martensitic matrix sample, although the bulk hardness of the as-welded matrix is 5% lower. The ferritic matrix sample has the poorest wear resistance behavior which is less than half of that of the as-welded matrix one. Micro-ploughing, micro-cutting, and micro-cracking are recognized as the micro-mechanisms in the material removal in which the proportion of micro-ploughing mechanism increased by increasing matrix toughness.     

The effects of welding processes on abrasive wear resistance for hardfacing deposits

In this research, four kinds of welding deposits were evaluated, applied through two different welding processes: flux cored arc welding (FCAW) and shielded metal arc welding (SMAW). The other variable of the tests was the deposited layers. The hardfacing deposits were evaluated using the dry sand-rubber wheel machine according to procedure A of the ASTM G65 standard. Optical and scanning electron microscopy was used for the characterization of the microstructure and worn surface of deposits. FCAW welds presented higher abrasive wear resistance than the SMAW deposits. The hardfacing deposit formed by uniformly distributed carbides rich in titanium presented the highest abrasive wear resistance. Abrasive wear resistance was higher when three layers were applied, except for SMAW-D deposit. It was not possible to get a clear relation between hardness and the abrasive wear resistance of the deposits. The results showed that the most important variable to improve abrasion resistance is the microstructure of hardfacing deposits, where the carbides act as barriers to abrasive particle cutting.     

Microstructure and Wear Resistance of Fe-Cr-C Hardfacing Alloy Reinforced by Titanium Carbonitride

In order to improve the wear resistance of Fe-Cr-C hardfacing alloy, titanium carbonitride was introduced in situ and a TiC-Ti_x(C,N)_y coating was deposited on the surface of ASTM G3101 steel by a gas metal arc welding process. The microstructure and wear resistance of the hardfacing layer were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDS), macroscopic hardness meter, spectrometry, and transmission electron microscopy (TEM). The results show that the hardfacing layers mainly consist of (Cr,Fe)₇C₃, TiC carbides, Ti_x(C,N)_y carbonitrides, and α-Fe (C_0.14Fe_1.86 and C_0.12Fe_1.88 martensite) (BCT) in addition to a low content of retained CFe_15.1 austenite (FCC). The titanium carbonitride–reinforced coating has high hardness and excellent wear resistance under dry sliding wear test conditions.     

The Microstructure and Abrasive Wear Resistance of Fe–Cr–C Hardfacing Alloys with the Composition of Hypoeutectic,Eutectic, and Hypereutectic at $$ \frac{Cr}{C} = 6 $$

In this investigation, three Fe–Cr–C hardfacing alloys with different carbon and chromium contents and in constant ratio of ( \fracCrC = 6 ) \left( {\frac{Cr}{C} = 6} \right) were fabricated by GTAW on AISI 1010 mild steel substrates. The OES, OM, SEM, and XRD techniques and Vickers hardness method were used for determining chemical composition, hardness, and studying the microstructure of the hardface alloys. The OES, OM, and XRD examination results indicated that different carbon and chromium contents of hardface alloys produced hypoeutectic/eutectic/hypereutectic structures. By increasing the carbon and chromium contents in the chemical composition of hardface alloys, the volume fraction of the total (Cr, Fe)₇C₃ is increased resulting to decreasing in total the austenite volume fraction and increasing the hardness of the surface. Studying the microstructure after wear test (ASTM G65) shows that at the edge of the worn surface, the transformation of austenite to martensite had occurred in all the samples. The wear test results indicate that the highest wear resistance is gained in the hypoeutectic structure with maximum hardness after the wear test. In addition, abrasive wear micromechanisms in hypoeutectic/eutectic/hypereutectic were recognized as: ploughing + cutting/ploughing + cutting + cracking/cracking + cutting, respectively.     

The abrasion endurance of hard weld deposits from chromium-manganese electrodes

The wear behaviour of hardfacing alloys obtained with five types of coated electrodes with various contents of chromium (1.6 to 12.5%) and manganese (0.8 to 1.8%), is presented. Relative abrasive endurance compared with carbon steel was determined by abrasive wear tests using a rotating disc machine. The highest relative endurance was obtained with a weld deposit with 1% manganese and 2.2% chromium, and a coarse grained austenite-martensite structure. Fully martensitic structures of higher hardness were inferior. The wear behaviour of hardfacing alloys depends upon both the structural components and the grain size shown by means of abrasive wear tests in laboratories or exploitation endurance tests. Abrasive wear testing can assess wear resistance and be a guide to service performance.     

Guidelines for the selection of hardfacing alloys for sliding wear resistant applications

The work presented in this report summarizes an evaluation of the relative sliding wear characteristics of several commonly used commercial hardfacing alloys. The alloys studied include cobalt-base, nickel-base and Fe-Cr-Ni alloys which also contain small amounts of cobalt. Selecting the most effective alloy combination to withstand sliding wear is a challenge for materials engineers, equipment designers and fabricators. Accurate guidelines for selecting compatible alloys from a wear resistance point of view are not available. On the basis of the results of this work several hardfacing alloy combinations were identified which provide good sliding wear resistance. In addition, several hardfacing alloy combinations were found to exhibit poor wear resistance compatibility. The guidelines presented in this report will aid in the selection of suitable hardfacing alloy combinations with adequate sliding wear resistance. The wear guidelines are also supplemented with corrosion data in several environments of importance in the chemical process industries. These data should assist in the selection and optimization of hardfacing alloys in the presence of aggressive environments.     

含钒高铬铸铁自保护金属芯堆焊焊丝的研制

研制了一种自保护金属芯堆焊药芯焊丝。堆焊过程飞溅小，焊缝成型美观。堆焊层组织为马氏体＋残余奥氏体＋碳化物硬质相。堆焊层硬度为HRC60，相对耐磨性为Q235钢的21倍。焊丝的熔滴过渡方式为典型的短路过渡。研究焊丝粉芯成分对焊丝的性能发现，石墨可以有效的降低飞溅，当粉芯中的石墨含量为3％时，堆焊过程中的飞溅率最低，此外增加粉芯中钒的含量，堆焊层的硬度和耐磨性上升。     

Microstructural and abrasive characteristics of high carbon Fe–Cr–C hardfacing alloy

A series of high carbon Fe–Cr–C hardfacing alloys were produced by gas tungsten arc welding (GTAW). Chromium and graphite alloy fillers were used to deposit hardfacing alloys on ASTM A36 steel substrates. Depending on the four different graphite additions in these alloy fillers, this research produced hypereutectic microstructures of Fe–Cr phase and (Cr,Fe)₇C₃ carbides on hard-facing alloys. The microstructural results indicated that primary (Cr,Fe)₇C₃ carbides and eutectic colonies of [Cr–Fe+(Cr,Fe)₇C₃] existed in hardfacing alloys. With increasing the C contents of the hardfacing alloys, the fraction of primary (Cr,Fe)₇C₃ carbides increased and their size decreased. The hardness of hardfacing alloys increased with fraction of primary (Cr.Fe)₇C₃ carbides. Regarding the abrasive characteristics, the wear resistance of hardfacing alloys were related to the fraction of primary (Cr,Fe)₇C₃ carbides. The wear mechanism was also dominated by the fraction of primary (Cr,Fe)₇C₃ carbides. Fewer primary carbides resulted in continuous scratches worn on the surface of hardfacing alloy. In addition, the formation of craters resulted from the fracture of carbides. However, the scratches became discontinuous with increasing fraction of the carbides. More primary carbides can effectively prevent the eutectic colonies from the damage of abrasive particles.     

基于钴基合金覆层的多层金属热锻模原型制备与性能

基于功能梯度材料(FGM)的思想制备多层金属热锻模是提高模具寿命的有效方法。采用焊条电弧堆焊制备了多层金属热锻模的原型试样,试样经焊后热处理后,进行了金相组织分析、显微硬度测试、磨损实验和冲击韧性测试等实验。实验结果表明:钴基合金堆焊层与W6Mo5Cr4V2堆焊层界面冶金结合情况良好;截面显微硬度呈梯度分布,表面钴基合金硬度达到492HV;制备的多层金属试样耐磨性是H13钢耐磨性的2.5倍,冲击韧性处于合理范围。