Luckily for me, they had a whole page dedicated to why gel nails can crack. Seat overlay made of stellite 6 is possible but not recommended by us. They are destined for parts lap or overlay weld stelliting. The stellite surface overlay becomes very hard, corrosive resistant, wear resistant and has high resistance to galling. Had to keep heat on it til it was completely welded. These alloying elements are in various proportions, with most alloys containing four to six of these elements. It is easily deposited by a number of methods but you do have to be careful about contamination from sulphur or phosphorus. Disbonding of stellite associated with combinedcycle plants has occurred primarily in parallelslide gate valves and nonreturn globe valves for hp and hotreheat service. In this chapter, the hardfacing of gate valves, and measurement of bead geometry and residual stresses induced are detailed. Pdf microstructure evolution and failure behavior of stellite 6. Stellite delamination in hp, hrh steam valves posted on may 22, 20 by team ccj stellite liberated from a large block valve was captured by the strainer protecting the steam turbine.
The following 19 answers to frequently asked questions may help you select. We do weld overlay of valve parts like balls, seat ring etc and heavy duty tube sheets as well. Deloro stellite says the hardness of its stellite 21 typically is 27 hrc and can workharden up to 40 hrc. This type of cracking will not affect the wear resistance. How to avoid stellite 6 crackings american welding society. Pdf delamination failures of stellite hardfacing in power plants.
We clearly mention that it is not possible to perform a stellite 6 completely free of hair cracks. When applying an overlay product, the contractor is adding strength to your pool deck, patio or other surface. Stellite alloys chemical composition, mechanical properties. Hard facing hf and corrosionresistancealloy cra with hot wire, materials. Alternate stellite process material selection and properties. Try using inconel as a butter layer and deposited stellite 6 on top of this butter layer to reduce susceptibility to cracking, during and after hardfacing. Example of weld overlay surface treatments with mechanical bonding may not stand up to harsh environments due to cracking and spalling. What is the best gas to use when doing a stellite overlay on 316ss. It is also possible to apply tungsten carbide containing nickel based overlay, although the high meltpool temperature places limitations on carbide size, volume fraction and binder alloy composition.
We built several new housings from scratch and before the stellite went on wed clad with stainless. Most crackings are perpendicular to the welding seam. I need info on welding satellite 6 to ss316 pretty much what the title said, i received a contract job to help out a company hardface their ss316 parts with stellite 6 filler so they can be machined back down to a certain height. It is very easy to apply as an overlay, compared with the traditional cobaltbase wear alloys. If it comes down to it, you made need a wps written out, what i gave you is basically what my procedure says. This alloy can be applied crack free with the proper welding procedures. Can duplex stainless steels be hardfaced without adversely affecting the base material properties. Microstructure evolution and failure behavior of stellite 6. The laserclad valve seats exhibited superior impact wear resistance, i. The laserclad layers, which consisted of refined solidification structures, were characterized by increased hardness and impact toughness as compared to pta overlays. At first glance, hardfacing can be confusing and troublesome. S induced stress corrosion cracking cracking at elevated temperatures in environments containing h 2 s is defined as a form of stress corrosion cracking.
This alloy also has higher hot hardness and resists galling like all stellite alloys when mated with another stellite alloy. Hardfacing is usually limited to one, two, or three. Because of the presence of the carbide network, the overlay is somewhat prone to cracking, although resistance to cracking is very good for an alloy of this hardness level. Aug 15, 20 stellite is a trademarked name of the deloro stellite company, now part of the kennametal group. Stellite 6 and 309l ss weld overlays were deposited in three different orders with identical welding parameters on the surface of 420 ss turbine blade using gtaw process. Since most hardfacing deposits have nearly no ductility, the welds will crack. Its a little technical, but the message behind it is basically that it all has to do with how the polish is applied. Lowcarbon hardfacing alloys, such as alloy 21, which has 0. Another approach is to apply a nickel based buffer layer as a first weld layer with little or no preheat and a very low interpass temperature. The material itself has been around since the 1900s and was originally seen as a substitute for traditional metal cutlery which suffered from general wear and tear and was also prone to staining. Effect of interlayers on the microstructure and wear. Aug 16, 2011 stellite is a registered trade mark of deloro stellite.
If a crack is found, the crack source needs to be completely removed, and repair welding is performed according to the original overlay welding process. Hardfacing a standard term for a wearresistant weld overlay is commonly used for seat and guide surfaces on valve trim of all. Stellite 6 high dilution aisi 410 stellite 720 stellite 6 aisi 410 100 90 80 70 60 50 40 30 20 10 0 0. Delamination failures of stellite hardfacing in power plants. Pdf delamination failures of stellite hardfacing in. Arc energys weld overlay cladding services are utilised by clients in a vast number of industry sectors where service conditions require corrosion resistant properties. Optical light micrograph of stellite 6 weld overlay, 200x, 5% hcl electrolytic etch. Understanding some of the basics about hardfacing can go a long way toward instilling confidence in your hardfacing product selection.
Stellite alloys are often used as a weld hardfacing on valves, spindles, and other. Known taken as a prototype of the present invention, a method of pripiski wear resistant stellite overlay on the front edge of the steel blade wet steam of the stage steam turbine using highmelting solder, whereby the solder powder mixed with antioxidant flux is poured between cleaned the contact surfaces of these solder parts, heat up the. The extent of check cracking of a hypereutectic weld overlay sample. Stellite alloys are nonmagnetic and typically associated with high corrosion resistance and as with many alloys, they are adaptable and can be refined for a range of specific applications. Wear characteristic of stellite 6 alloy hardfacing layer by. This is personal experience from the my time in the electric power industry stellite 6 typically is applied only in shop and not in the field. Invented by elwood haynes in the early 1900s as a substitute. C were investigated by plasma arc surfacing processes on q235 steel. Stellite 6 welds pretty clean unless it gets oxidized and then the puddle gets sluggish. Chrome carbide stellite usually craze crack not considered detrimental to wear resistance.
Stellite synonyms, stellite pronunciation, stellite translation, english dictionary definition of stellite. Investigation of the wear resistance of high chromium. If you need a bearing on a shaft, build it up with 308, and then turn down until you are about 0. Stellite is a nonmagnetic alloy which contains a variety of different metal components with the main elements being cobalt and chromium. Stellite 3 is superior and this improved resistance increases as loads are increased or speeds are increased to 10 times to 25 times that of stellite alloy 6 or 12. It can lead to unexpected sudden failure of normally ductile metal alloys subjected to a tensile stress, especially at elevated temperature. The issue of whether hardfacing adversely affects the properties of duplex stainlesssteel base materials depends on several factors.
When they are applied to steels by hardfacing, there is intermixing of the stellite alloy and the steel, resulting in a higher iron content in the overlay, especially in the first layer. The netlike m23c6 eutectic carbides in the stellite 6 coating transformed to. Stellite 6 can be successfully welded when high levels of preheat are applied. They differ in the amount of deformationand heat used toform thebond and in the method of bringing the metals into intimate contact. Tribological test was conducted to characterize the wear property. Build up seriously worn areas should be rebuilt close to working size using tough, crackresistant welding materials which can be deposited in an unlimited number of layers. Alloy of cobalt from 50 to 65 %, chromium from 25 to 35 %, tungsten from 4 to %, carbon from 1 to 2,5 % and other elements molybdenum, nickel, iron, titanium.
Weld overlay is one of the established manufacturing line for us. Good luck, stellite can be a real bugger and patching cracks and holes post weld is like 99% likely to crack it so hopefully it goes on well the first time. Stellite 21 overlay 2740 hrc astm a479 uns s31600 overlay which may be prone to cracking or separation from the substrate. Hardfacing wear resistant surfaces deposited on the base metal or on build up deposits extend service life. This article is based on what that research team has discovered. Tungsten carbide hardfacing from hardface technologies.
Author links open overlay panelyingwuyanliu huichen. The base plate is fairly thin and heat build up is inevitable. Material of over lay consists of inconel 625, inconel 825, stalite, ss 316l, ss317l, duplex and super duplex. Stellite is a registered trade mark of deloro stellite. Hardfacing alloys and processes for advanced ultrasupercritical. If you try welding alloy 6 to something else, its probably going to crack. Developing the ductility and thermal fatigue cracking property of.
Ultraflex surface treatment cutting tool engineering. There are a large number of stellite alloys composed of various amounts of other alloying elements such as nickel, iron, aluminum, boron, carbon, manganese, phosphorus, sulphur, silicon, and titanium. For small, simple parts, cracking is not a usually a problem. Cracking has been observed in valve components at the stellitesteel. Build up seriously worn areas should be rebuilt close to working size using tough, crack resistant welding materials which can be deposited in an unlimited number of layers.
Anytime you have an adhesive, abrasive or erosive atmosphere, we recommend that you use stellite coatings on your machine parts to increase productivity. The alloys may also contain tungsten or molybdenum and a small but important amount of carbon. For components such as the bottoms pumps in fluid catalytic cracking units, harsh abrasion and erosion can destroy components within a matter of months. Plasma transferred arc welding of stellite 6 alloy on stainless steel for wear resistance. However, when we finished the second layer and let it cool gradually wrapping the cone with insulate material, we could see some crackings on the second. These hardfacing layers are applied as an overlay onto a steel substrate, such. Stellite is a range of cobaltchromium alloys designed for wear resistance. These hardfacing layers are applied as an overlay onto a steel.
Prior to that it was owned by union carbide, stellite division. In this application the stellite always had cracks in it but it didnt matter. Hardfacing alloys and processes for advanced ultra. Hardfacing has been liberated from valve seats, guide rails, and discs. The editors first learned of stellite delamination in a large valve designed for highpressure hphightemperature steam service at the 2009 7f users group conference. In some applications, we have used inconel as a butter layer and deposited stellite 6 on top of this butter layer to reduce susceptibility to cracking, during and after hardfacing. Crack repairs in stellite may highlight cracking in base material, with propagation through the overlay.
Pdf solidification structure of stellite overlayer formed. Microstructure evolution and failure behavior of stellite. This article provides an overview of work done to evaluate suitable alternatives to stellite 6. Hightemperature hardness and wear resistance of stellite alloys by samit kapoor a thesis submitted to the faculty of graduate and postdoctoral affairs in partial fulfillment of the requirements for the degree of master of applied science in mechanical engineering carleton university ottawa, ontario 2012, samit kapoor. Probably after final machining the surface will show hair cracks which is normal in case of using stellite 6 and this do not affect the sealing functiont we. Ultraflex features a metallurgical bond and unique benefits to extend component life. Welding tips and tricks view topic kennametal stellite. I have also used slightly increased preheat, and tight stringer beads to deposit stellite 6 directly on top of low alloy steel.
Since the thickness is 5mm, we have to do 2 layers. Not familiar with your rod so i dont know the hardness rating there are many factors involved when hard facing according to the nature of the part but as a general rule its not good practice in the type of things i do to use 600 or over hardness without buttering the base metal with say 400 first this is when cracking seems to be a problem if your stuck in the. In comparison to traditional welding, the ultraflex process metallurgically bonds the wear system. Weld overlay, weld overlay of satellite, weld overlay of. Hightemperature hardness and wear resistance of stellite alloys. I always preheated a minimum of 300 degrees f up to 600 degrees f and wrap the piece in cerwool so it would cool slowly. These types should not be used where cracking is undesirable, eg. Mar 08, 2005 this robot is hardfacing an agricultural tool.
The solidification structures of the overlayers of stellite 1, 6 and 21 cobalt base alloys after overlaid on spheroidal graphite cast iron by plasma transferred arc process were studied in this. Welding of stellite strap on steam turbine blade leading edge. Stellite 6 is a cobalt based alloy but is very tolerant of dilution from other materials and is often used on stainless to give a wear resistant area, e. Pdf an experimental study of welding parameters for. Figure 5 shows that the hardness drops more or less linearly with dilution up to. The test samples of coated stellite 6 were taken as pins 6 x 6 x 28 mm and forged alloy steel din 1. Obvious diffusion of fe occurred from the steel and fusion zone to the stellite overlay, resulting in the microstructure evolution and hardness increase in the coating, where hard cofe phases. Most often these cracks are transverse cross cracks, which are very beneficial to relieve the residual stress in the weld bead. Materials are type 304l stainless steel and mediumcarbonsteel. Concrete pool deck resurfacing can spice up your old pool deck without the hassle of tearing out the old concrete and pouring new. The effect of applied interlayers on microstructure, dilution, hardness, and wear resistance of the cladded layers were investigated.
The results showed less cracking and pore development for stellite 6 coatings applied to. In stellite alloys this generally has the following effects. Pdf delamination failures of stellite hardfacing in power. Weld overlay cladding provides the assurance of a heavyduty metallurgicallybonded protective layer that will not be undermined or dislodged in service. Co and cr, fe 7 c 3 nov 21, 20 i have been trying to find some stellite 6 sleeves to make wear sleeves on a shaft which runs in a hanger bearing. An experimental study of welding parameters for stellite6 overlay on inconel825 using ptaw process. It is a low carbon cobaltchromium alloy strengthened with mo. The matrix is resistant to acids, bases, lye and other corrosive media. Stainless steel cladding and weld overlays 109 clapding metal. Stress corrosion cracking scc is the growth of crack formation in a corrosive environment. Wear characteristic of stellite 6 alloy hardfacing layer.
Plasma transferred arc welding of stellite 6 alloy on. Stellite definition of stellite by the free dictionary. When we finished the first stellite 6 layer, there is no cracking found. Stellite 6 is a well know overlay in the pump and valve industry. Kennametal, velan and carleton university formed a research team to evaluate new hardfacing alloys and application processes for advanced ultrasupercritical applications. Impact wear resistance of stellite 6 hardfaced valve seats. Thermal fatigue cracking is one of the main lifelimiting factors for the brake discs of trains. Pool deck resurfacing is a process that either repairs damaged concrete surfaces or updates their look. For components such as severe service valves, the stellite alloybased grade of ultraflex ensures that there is no cracking or delamination of the surface to protect the substrate. Stellites are very resistant to wear, corrosion in acidic environment and hot oxidation.
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