Hardfacing Layer Research Articles

Resistance of Cladding Layers Made by FCAW Method to Erosive Wear

The paper deals with the tribological properties of investigated types of hard-faced materials at erosive wear process. Influence of inclination angle of elements on friction resistance and microhardness changes of hard-faced layer were investigated too. From quantitative aspect were hard-faced layers evaluated on the base of weight loses. From achieved results follow that inclination angle is one from determining factors on to material’s wear measure.

AN ANALYSIS OF THE WEAR OF PLOUGHSHARES WITH VARIOUS TECHNOLOGICAL SOLUTIONS

The paper analyses wear processes in various technological forms of ploughshares. Tests involved ploughshares made of Hardox 500, B 27 and 38GSA steel, as well as Hardox 500 steel with the cutting edges hardfaced by means of an El – Hard 63 electrode on the front and back sides, as well as 38GSA steel hardfaced by means of an EStelMn60 electrode. The tests were conducted during natural operation when processing sandy soil. During the tests, the changes in the mass and geometry of ploughshares were measured as a function of the processed area. Ploughshares made of steel were characterised by a diverse martensitic microstructure. The hardfaced layers, on the other hand, were dominated by chromium carbides with alloy ferrite. It has been concluded that the use of hardfaced layers considerably impact the decrease in the intensity of wear of the tested working elements. On the other hand, no significant differences were observed in the wear processes of hardfaced ploughshares depending on the native and additional material and the place of the application of the hardfacing agent. In the analysed soil conditions, ploughshares made of steel did not exhibit any significant differences in the wear process.

Calculation of Fusion Zone Size in the Submerged-Arc Hardfacing of Rolling-Mill Rolls

Results are presented from calculation of the dimensions of the fusion zone in the hardfacing of rollingmill rolls by a composite strip electrode. The calculation is performed on the basis of the solution of a differential equation of heat conduction that accounts for the temperature dependence of the thermophysical properties of the material comprising the rolls. Heat propagation in a semi-infinite body undergoing hardfacing is modeled by the finite-element method. The values calculated for the depth of fusion agree well with the experimental data. The calculated results are used to determine the effect of the parameters of the composite electrode on the formation of the weld pool and the conditions necessary to obtain a macroscopically heterogeneous composition with a prescribed hardness distribution across the hardfaced bead (weld). The uneven wear being exhibited by such a heterogeneous hardfaced layer formed on the work roll of a roughing scale-breaker in a wide-strip hot-rolling mill is making it easier to remove scale from the surface of the rolled product.

Application of titanium machining chips in welding consumables for wear-resistant hardfacing

Equipment of sugar cane plants and mineral extraction are submitted to severe abrasive wear conditions. Welded hardfacings are usually applied to repair this kind of damage, where commercial chromium/carbon-rich welding consumables have usually been employed. In the present work we investigated the microstructure of experimental hardfacings made by addition of residues (chips) collected from the machining of ASTM F67 (unalloyed Ti, grade 4) alloy. Mixtures with different carbide-formers (Cr/Nb ferro-alloys) were also tested. Two layers of ‘pure’ chips (Ti), chips plus Fe–Cr (Ti–Cr), and chips plus Fe–Nb (Ti–Nb) were applied on low-carbon steel specimens by the GTAW/TIG process. The microstructure of hardfacing layers was observed by optical and scanning electron microscopy (SEM) equipped with EDS microanalysis. The microstructural characterization has determined that carbide distributions change significantly with the chemical nature of the hardfacing. SEM observations coupled with EDS microanalysis have confirmed the formation of complex carbides within the metal weld, whose stoichiometry was determined by X-ray diffraction (XRD) analysis. Mixed carbides of MC type and some cementite have been found. As a result it was suggested that use of ASTM F67 chips as carbide formers for composition of welding consumables can contribute to improved wear resistance of hardfacings, if compared with traditional chromium-based hardfacings.

Experimental Determination of Residual Stresses in the Hard-faced Layers after Hard-facing and Tempering of Hot Work Steels

The procedure for experimental determination of the longitudinal and lateral residual stresses in the multi-layer hard-faced plates, made of the hot work tool steel used for forging dies manufacturing, is presented in this paper. The objective of this research was to establish the influence of the multi-layer hard-facing on residual stresses in the thin and thick plates, which could later, in exploitation, cause the appearance of cracks and fracture. The influence of tempering on decreasing the residual stresses was monitored, as well. The plates were hard-faced in three layers, while the stresses were measured by the magnetic method. The obtained results have shown, among others, that the residual stresses are higher in the thick plates, as well as that the proper regime of the heat treatment can significantly reduce the level of residual stresses.

Fe-V-B ESASLI ALAŞIMLA YÜZEYİ SERTLEŞTİRİLMİŞ AISI 1020 ÇELİĞİNİN ÖZELLİKLERİ

In this study, Fe-V-B based hardfacing layer produced on AISI 1020 steel surface and analyzed by TIG welding technique. Ferrous vanadium, ferrous boron and armco iron prepared in Fe 10 V 5 B 5 , Fe 12 V 5 B 3 and Fe 14 V 5 B compositions were used for surface alloying treatment. Morphological properties, phase analysis and hardness measurement of hardfacing layers analyzed with optical microscope and scanning electron microscope, x-ray diffraction and vickes indentation, respectively. 2-3 mm thickness is observed from morphological investigation in Fe-V-B based hardfacing layer. Alloyed layers indicate good quality thick coating and porosity free of hardfacing. X-ray difraction analysis showed that the alloyed layers include FeV, Fe2B, VB ve Fe. It was shown that surface alloyed layer has composite structure including steel matrix and well distributed boride phases. The hardness of matrix of the alloyed layer and steels' un-coated layer are 205 HV 0,1 ve 150 HV 0,1 , respectively.

Effect of nano-additives on microstructure, mechanical properties and wear behaviour of Fe⿿Cr⿿B hardfacing alloy

Fe⿿Cr⿿B hardfacing alloys with different nano-additives content were investigated. The effects of nano-additives on the microstructures of hardfacing alloy were studied by using optical microscope, scanning electron microscope, X-ray diffractometer. The hardness and the fracture toughness of hardfacing alloys were measured, respectively. The sliding wear tests were carried out using a ball-on-disc tribometer. The experimental results showed that primary carbide of hardfacing alloys was refined and its distribution became uniform with content of nano-additives increased. The hardfacing alloys are composed of Cr7C3, Fe7C3, α-Fe and Fe2B according to the results of X-ray diffraction. The hardness of hardfacing alloys increased linearly with the increase of nano-additives. The hardness of the hardfacing alloy with 1.5wt.% nano-additives increased 54.8% than that of the hardfacing alloy without nano-additives and reached to 1011HV. The KIC of the hardfacing alloy with 0.65wt.% nano-additives was 15.4 MPam1/2, which reached a maximum. The value increased 57.1% than that of the hardfacing alloy without nano-additives. The wear rates of the hardfacing layer with 0.65wt.% and 1.0wt.% nano-additives decreased about 88% than that of the hardfacing layer without nano-additives. The main wear mechanism was adhesion wear.

Influence of Flux-Core Arc Welding Parameters on Erosion Resistance of Stellite 12

Due to high wear resistance, Cobalt-based alloys, such as Stellite12 (52Co30Cr8.5W), have presently been used as materials for hardfacing in several applications. Thermowell, a protecting part for thermocouple in petrochemical production, is also coated by Stellite12. Because of high deposition rate, the flux-core arc welding (FCAW) method was selected to be hardfacing process in the research. However, their welding parameters should be exactly controlled in order to obtain desired properties, depending on the microstructure of this material. The objective of this experiment is to study the influence of the FCAW parameters on the erosion resistance of AISI 304 (Fe-18Cr-8Ni-0.06C) welded by the cobalt base alloy filler, Stellite12 (Co-30Cr-8.5W-1.5C) as the hardfacing layer. The studied parameters were welding speed in the range of 2.1-8.5 mm s-1, and wire feed speed in the range of 42.3-67.7 mm s-1, leading to different heat inputs and cooling rates. The erosion resistance was investigated by using solid particle erosion test rig at ambient temperature. Surface characterization was then carried out by SEM equipped EDX and XRD. The results showed the relationship between erosion resistance and microstructure in welding and HAZ zone. The erosion resistance was depended on the formation of interdendritic phase in the welding zone. According to the surface examination, it was found that the formation of interdendritic, including size and shape played an important role on the erosion resistance. The heat input and cooling rate concerned with welding parameters was further discussed with the erosion behavior in this research.Keywords Stellite12, Cobalt base alloys, Flux-core arc welding, FCAW, Erosion-resistance

Application of a Composite Hot Shearing Tool Manufactured by Co-Spray Forming

In modern manufacture, like in automotive industry, high quality products and high output rates as well as low costs are achieved by highly efficient processes. Optimized tool design represents a key factor for such processes, leading to long tool life and hence to low tooling costs. Early in the industrial manufacturing chain of roller bearings for example, hot bars are sheared into billets, which are subsequently transported automatically to the first forming stage of a press. The shear blades should have a high wear resistance at high temperatures. In this study the first bi-metal composite shear blade made by spray-forming has been developed and tested in industrial environment. The composite tool has been deposited in a co-spray forming process to directly combine a hard-facing alloy layer with a hot working steel body in order to take advantage of the high microstructural homogeneity and the low segregation generated in spray forming. After machining, heat treating and quality inspection of the new material composite, the hot working tool was used in manufacture to prove its wear resistance and durability. The results show that the interface properties of the composite are of high quality and the material has a lower vulnerability to cracks after use in production than the conventional tool, respectively material. Only the porous zone near the interface leads to fissures which are partially going deep into the tool. Hence the parameters of the co-spray forming process need to be improved.

Wear Behavior of Hardfacing Deposits on Hadfield Steel

The objective of this research was to develop the welding procedure for multilayer hardfacing of 13% Mn cast steel and study behavior of hardfacing deposits after impact applied. Austenitic stainless steel and martensitic hardfacing electrode were selected as buffer and hardfacing, respectively. Two different atmospheric conditions were compared which the first was controlling cooling rate on specimen by water during welding and another was un-controlling (by air), using shielded metal arc welding (SMAW) process. Macrostructure and microstructure were investigated by optical microscope. The hardfacing deposits were also determined by the dry sand rubber wheel machine according to procedure A of the ASTM G65 standard. The results indicated that the hardfacing layers revealed martensitic type microstructure in both controlled and uncontrolled cooling rate but their grain shapes were a little difference. For buffer layer showed austenitic type microstructure. And base metal layer presented amount of carbide in controlled cooling rate is less than in another one. The best wear resistance was obtained from controlled cooling rate condition.

The effect of microstructure on abrasive wear of a Fe–Cr–C–Nb hardfacing alloy deposited by the open arc welding process

The relationship between abrasive wear resistance and microstructure of a hardfacing alloy based on Fe–Cr–C–Nb system (CNO) was investigated. This material was developed for cladding, by an open arc welding technique, of components subjected to severe abrasive wear. The work undertaken included microstructural characterization and abrasion testing. Microstructural examinations of hardfaced layer showed that the microstructure of the alloy consisted of a large volume fraction of primary niobium carbides randomly dispersed in a eutectic matrix comprised of metastable austenite (γ) and eutectic M7C3 carbides as well as a high volume fraction of primary M7C3. Abrasive wear tests, in low stress and high stress, showed that the developed Fe–Cr–C–Nb hardfacing alloy exhibited improved abrasive wear resistance in comparison with the conventional high carbon/high chromium hardfacing alloy with higher hardness and higher volume fraction of primary M7C3. Owing to its better wear resistance and its relatively low cost, the alloy CNO may be a successful replacement of the more conventional hardfacing material for the refurbishment of components subjected to severe abrasive wear in order to extend their service life.

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-Tix(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, Tix(C,N)y carbonitrides, and α-Fe (C0.14Fe1.86 and C0.12Fe1.88 martensite) (BCT) in addition to a low content of retained CFe15.1 austenite (FCC). The titanium carbonitride–reinforced coating has high hardness and excellent wear resistance under dry sliding wear test conditions.

Thin Surface Layers of Iron-Based Alloys Deposited by TIG Hardfacing

Hardfacing layers developed by tungsten inert gas (TIG) surface melting on commercial purity titanium placing with a mixture of Fe, C and Si powders under two different traverse speeds (1 mm/s and 2 mm/s) and energy input of 1080 J/mm in an argon gas environment were investigated in terms of surface condition, microstructure, hardness and wear of the processed tracks. The surface appearance of treated layers was found to be free from any obvious defect. The TIG hardfacing layer produced dendritic structure due to dissolution of preplaced powder in the Ti melt. A maximum microhardness value of 630 HV 0.5 kgf was found on the surface layer processed with lower speed which was 2.5 to 3.5 times higher than the base material. Ball-on-plate wear tests exhibited better performance of the hardfacing layer than the untreated CP-Ti which is attributed to the presence of carbides and silicides in the Ti melt.

Wear Behavior of Fe-C-Cr Based Hardfacing Alloys Dependent on Ferrovanadium and Ferrotungsten Addition*

Abstract The aim of this study is to investigate the effect of vanadium and tungsten on wear behavior of Fe-C-Cr based hardfacing alloys. The wear behavior of hardfacing layers was determined by dry sand/rubber wheel abrasion tests according to ASTM G-65. The results of the abrasion tests were interpreted by metallographic examinations, SEM and EDX analyses as well as hardness measurements. According to the results of the experimental studies, the effect of W and V addition was discussed.

Aplicação de cavacos de titânio para produção de revestimentos resistentes ao desgaste

Equipamentos usados nas usinas sucroalcooleiras e de extração mineral são submetidos a condições severas de desgaste abrasivo. Revestimentos duros são usualmente aplicados para reparar este tipo de dano, sendo bastante empregados consumíveis de soldagem contendo altos teores de cromo e carbono. No presente trabalho visa investigar a microestrutura de revestimentos duros formados com a fusão de cavacos de titânio puro ASTM F67 grau 4, material usado na fabricação de implantes odontológicos. Misturas com diferentes formadores de carbonetos (Fe-Cr e Fe-Nb como aditivos) também foram testadas. Revestimentos feitos com duas camadas de cavacos "puros" (Ti), cavacos com Fe-Cr (Ti-Cr) e cavacos com Fe-Nb (Ti-Nb) foram depositadas sobre peças de aço-carbono por soldagem TIG/GTAW. A microestrutura das camadas foi observada com microscópio óptico e por microscópio eletrônico de varredura equipado com microanálise. A caracterização microestrutural revelou que a distribuição de carbonetos varia significativamente com a natureza química dos aditivos usados. A microanálise mostrou que houve a formação de carbonetos com composição química complexa no seio do metal de solda, cuja estequiometria foi determinada com análise por difração de raios-X. Carbonetos mistos do tipo MC e cementita foram identificados. Os resultados apresentados indicam que a aplicação de cavacos de titânio ASTM F67, como insumo para formação de carbonetos, pode contribuir para melhorar a resistência ao desgaste em comparação aos tradicionais revestimentos duros com carbonetos de cromo.

Analyse eines durch das Co-Spray-Verfahren hergestellten Werkzeuges zur Warmumformung

Abstract In the industrial manufacturing chain of roller bearings the hot bars are subsequently sheared into billets and these are automatically transported to the first forming stage of the press. Normally the cobalt-based hard-facing alloys for the blades are deposited by manual metal arc or plasma transfer arc welding. In the research work presented here, the hard-facing alloys are produced by spray forming to increase the life time of the tool. Long life time is expected because of the advantages of spray forming: homogeneity of the microstructure, a low segregation and absence of a heat affected welding zone. For this purpose a bi-metal composite is deposited in a co-spray process to combine the hard-facing alloy layer with a hot working steel to insert the blade into a carrier. The interface between the two different materials was analyzed in terms of porosity, hardness, adhesive strength and machinability to describe the new composite material.

3 차원 유한요소해석을 이용한 Stellite21 초합금으로 하드페이싱된 STD 61 열간금형강의 열응력제어층 재료조합 및 두께 예측

하드페이싱층과 기저부의 결합부에서 발생하는 잔류 응력/변형률을 감소시키기 위하여 열응력제어층에 대한 연구가 시작되고 있다. 이 연구에서는 3 차원 유한요소해석을 이용하여 Stellite21 초합금으로 하드페이싱된 STD61 열간금형강의 중간층으로 형성된 열응력제어층의 재료조합과 두께를 예측하고자 한다. 열응력제어층은 Stellite21 과 STD61 의 조합으로 생성하였다. 열응력제어층의 두께범위는 0.5-1.5 mm 로 선정하였다. 유한요소해석 결과를 이용하여 열응력제어층을 구성하는 Stellite21 과 STD61 의 혼합율 및 열응력제어층 두께에 따른 시편 내부 온도/열응력/열변형률분포를 정량적으로 분석하였다. 이 결과로부터 적합한 열응력제어층의 재료혼합비는 Stellite21 50 % 와 STD61 50 % 이며, 적절한 열응력제어층의 두께는 1.0 mm 임을 알 수 있었다.

Delamination failures of Stellite hardfacing in power plants: a microstructural characterisation study

In recent years, several incidents of cracking and failures have been observed in Stellite (Stellite is a registered trademark of the Deloro-Stellite Corporation) hardfacing used in valves of modern high temperature combined cycle gas fired power plants. These hardfacing layers are applied as an overlay onto a steel substrate, such as CrMo steel (i.e. Grade 22, WC9) or creep strength enhanced ferritic steel (i.e. Grade 91, C12A). Cracking has been observed in valve components at the Stellite/steel interface and in the weld dilution zone formed between the steel and clad. Ultimately, disbonding or delamination of the weld hardfacing from the valve body occurs and has resulted in collateral damage to components in the plant (such as to the turbine) or valve failure. In this study, the microstructure formed near the Stellite/steel interface is investigated. Based on thermodynamic modelling, microstructure formed at these regions is hypothesised and a simple methodology is proposed to predict the occurrence of these failures.

Microstructural evolution with various Ti contents in Fe-based hardfacing alloys using a GTAW technique

The aim of this study is to discuss the effect of microstructural development with different Ti contents in Fe-based hardfacing alloys. A series of Fe-Cr-C-Si-Mn-xTi alloy fillers was deposited on SS400 low carbon steel substrate using oscillating gas tungsten arc welding. The microstructure in the Fe-based hardfacing alloy without Ti content addition included: the primary γ, eutectic γ+(Fe,Cr)3C, eutectic γ+(Fe,Cr)2C and martensite. With increasing Ti contents, the microstructures showed the primary TiC carbide, γ phase and eutectic γ+(Fe,Cr,Ti)3C. The amount and size of TiC carbide in the hardfacing layers increased as the Ti content increased. However, the eutectic γ+(Fe,Cr,Ti)3C content decreased as the Ti content increased. According to the results of the hardness test, the lowest hardness value (HRC 54.93) was found with 0% wt% Ti and the highest hardness (HRC 60.29) was observed with 4.87 wt% Ti.

Effect of Hardfacing Processes on Ballistic Performance of Q&T Steel Joints

Abstract This study was carried out to evaluate the effect of hardfacing processes on the ballistic performance of armour grade quenched and tempered (Q&T) steel welded joints. Two joints were fabricated using 4 mm thick tungsten carbide (WC) hardfaced middle layer, above and below which austenitic stainless steel (SS) layers were deposited on both sides of the hardfaced interlayer. Plasma transferred arc (PTA) hardfacing and shielded metal arc (SMA) hardfacing processes were used to deposite WC interlayer. In both joints, SS layers were deposited by shielded metal arc welding (SMAW) process. The fabricated joints were tested for its ballistic performance and the results were compared with respect to depth of penetration (DOP) on weld metal and HAZ locations. From the ballistic test results, it is observed that both the joints successfully stopped the bullet penetration at weld center line. Of the two joints, the joint made with SMA hardfacing offered a maximum resistance to the bullet penetration with a DOP of 16 mm without any bulge at the rear side of the weld center line. The gradual increment in hardness in the front layer is the primary reason for the successful intact of the bullet with a lesser depth of penetration.