Descriptions of the nibase colmonoy 5, nucalloy 453, and nucalloy 488 and febase norem 02, nocom2, and elmax candidates and stellite 6 have been previously presented. Solves the everyday problem steel welding applications in industry. Hard facing hf and corrosionresistancealloy cra with hot wire, materials. Cobalt alloy stellite, creep resistant steel, overlay welding, plasma transfer arc pta welding. Hightemperature hardness and wear resistance of stellite. Dry sliding wear map for stellite 6 against a wcco 9010 disc 12 49 figure 214. Delamination failures of stellite hardfacing in power plants. What is the best gas to use when doing a stellite overlay on 316ss. The microstructure of stellite 6 contains hard m7c3 carbides in interdendritic regions of the. The most common welding technologies implemented for overlay are the oaw. However, few studies have been carried out for coatings such as weld overlay. 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. The microhardness variation of machined surfaces of stellite 6 using different tool.
Aug 15, 20 the carbides present in the cocrwbased stellite alloys are of chromiumrich m 7 c 3 type. How to control check cracking and use to your advantage. Can duplex stainless steels be hardfaced without adversely affecting the base material properties. Cobalt alloy 6b stellite 6b is a cobaltbased, chromiumtungsten alloy used extensively in wear environments where its low friction coefficient minimises the risk of seizing and galling, even in applications where lubrication is not practical. Cobalt alloy 6b stellite 6b ams 5894 aircraft materials. Failure analysis of surface stellite alloy overlayer on disc of wedge. So it is possible to apply the material without cracks but in cases where the hard facing also is used for corrosion resistance or for a perfect. Hardfacing a standard term for a wearresistant weld overlay is commonly used for seat and guide surfaces on valve trim of all styles. The results showed less cracking and pore development for stellite 6 coatings applied to the mild steel ms substrate. Welding and hard facing consumables electrodes wires.
Spectacle blind flanges threaded flanges welding neck flanges other flanges. In single layer applications you probably will have small cracks. The dilution region is the region where melted substrate forms a mixture with coating material and possesses microstructure similar to the coating. Stellite 6b is supplied in the solution treated condition to ams 5894 and its wear resistant. Without a heat treat oven, slow cool generally means completely burying the part in a big cat box filled with vermiculite and leaving it alone at least overnight. Due to its characteristics of wear resistance, corrosion resistance, oxidation resistance and high temperature resistance, it is widely used in. For stellites 6 and 12, the content of w and cr was higher in the interdendritic zone whereas in stellite 21 were the elements mo and cr.
Stellite is a nonmagnetic alloy which contains a variety of different metal components with the main elements being cobalt and chromium. Check availability with our sales department by submitting your inquiry below to see if a metal source, llc can provide your stellite alloy metal requirement grades available. Cavitation erosion resistance of stellite alloy weld. Microstructure evolution and failure behavior of stellite 6. Pdf delamination failures of stellite hardfacing in. The stellite 6 hardfacing prepared with the same laser process parameters is also. Residual stresses analysis in ndyag laser welded joints. Never attempt without pwht on a welded low alloy steel with stellite 6 application. Seat overlay made of stellite 6 is possible but not recommended by us. The top diameter of the cone is mm,while the other is 300mm,and the thickness of the cone is 12mm duplex steel,that is sa516 gr.
The pta process is typically used to apply relatively thick i. Also we can apply other materials such as stellite 6 or 12 or nickel ni 100%. The issue of whether hardfacing adversely affects the properties of duplex stainlesssteel base materials depends on several factors. If that temperature is increased to the point that cracking is alleviated, the interpass temperature required to avoid adverse effects in the duplex stainlesssteel base metal will be exceeded. Hpa cobalt 6b is a wear resistant alloy used for stems, balls, rails and bushings. The interface area in laser cladding, microstructures and mechanical properties of which determine the structural integrity of the laserdeposited coating, consists of two distinctive zones. Fisrtly, we had a 3mm thickness of 309mol overlay with fcaw. Alloy 6b uns r30016 ams 5894 description alloy 6b is a cobaltbased alloy with great wear, erosion and abrasion resistance. Stellite is a family of completely nonmagnetic and corrosionresistant cobalt alloys of various compositions that have been optimised for different uses. Evaluation of microstructure and mechanical properties at.
The microstructure of stellite 6 contains hard m 7 c 3 carbides in interdendritic. 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. The sequence of the primary welding process and the following secondary processes of machining, and heat treatment has been modelled to predict the residual conditions in a stellite 6 overlay weld on a p91 steam turbine valve. This paper deals with the investigation of the microstructure and wear behavior of the stellite 6 cladding on precipitation hardening martensitic stainless steel 174ph using gas tungsten arc welding gtaw method. Guidelines for stellite hardfacing onto steels page 2 of 7 march 22, 2007 carbon equivalent vs preheat temperature 0 50 100 150 200 250 300 350 0. When we finished the first stellite 6 layer, there is no cracking found. The trademark owners of stellite claim that stellite 6 is the most widely used of their range of stellite alloys, offering a proven industry standard for generalpurpose wear resistance, and high mechanical and chemical perfromance in hostile environments. May 11, 2012 stellite 6 properties and applications. We took the method of smaw with the stick electrode of stellite 6. The dilution region is the region where melted substrate forms a mixture with coating material and possesses microstructure similar to the. It is a trademarked name of the deloro stellite company and was invented by elwood haynes 1 in the early 1900s as a substitute for cutlery that stained or that had to be constantly cleaned. Failure analysis of stellite overlay on the surface of wedge gate valve.
Pwht is also required to reduce tensile stresses as much as possible for a hard facing stellite 6 application. Laser cladding, hvof, plasma spraying, stellite 6 coating, friction and wear, nickel alloy. The basics of stellites in machining perspective international. A metal source, llc stellite alloysstellite alloys. It is easily deposited by a number of methods but you do have to be careful about contamination from sulphur or phosphorus. Weld overlay coating, also known as hardfacing, is a method which involves application of hard and wear. Kennametal, velan and carleton university formed a research team to evaluate new hardfacing alloys and application processes for advanced ultrasupercritical applications. We clearly mention that it is not possible to perform a stellite 6 completely free of hair cracks. Cocrw meets or exceeds ams 5894, pwa 1196, mcs 1012 and uns r30016. The hot hardness of stellite 6 weld overlays drops off sharply as iron content increases up to 10%fe, but at higher fe contents the drop is insignificant up to 20%fe. Stellite 6 is a cobaltbased alloy consisting of complex carbides in a matrix. However, when parts become larger or more complex, alloy 6 will crack unless the preheat temperature is increased. Stellite failure on a p91 hp valve failure investigation. This alloy also has higher hot hardness and resists galling like all stellite alloys when mated with another stellite alloy.
Review hardfacing steel with nanostructured coatings of stellite6 by supersonic laser deposition rocco lupoi1, andrew cockburn1, chris bryan1, martin sparkes1, fang luo2 and william oneill1 the ability to manufacture coatings is critical to engineering design. Stellite 3 valve,stellite 3 flanges,stellite 3 pipe. Preheating of substrate could reduce thistendency of cracking but. A comparative study for wear resistant of stellite 6. Stellite 6 welds pretty clean unless it gets oxidized and then the puddle gets sluggish. The material is also resistant to erosion and most. Introduction 1stellite 6 is a very versatile material that is used for hardfacing various component parts for applications requiring wear resistance. Stellite6 is a cobaltbased alloy consisting of complex carbides in a matrix. Stellite 6 is a well know overlay in the pump and valve industry. I voice over and commentate, change angles, overlay images, change backgrounds, and feature individuals who are shown on the channel to help create a story. Stellite alloy, commonly known as cobaltbased alloy, is a kind of cemented carbide with co, cr and w as the main elements.
If this is not a critical factor and you are using a rigid setup, i see no problems in using the 60 grit with a higher infeed. Further, the stellite coating on mild steel was significantly harder than that deposited on the superalloy. Usually, on a cracked or worn out valve disc with low alloy steel material grades, it is preferable to give a buttressing layer of inconel 625 or equivalent. The different process steps are coupled in order to transfer the residual conditions from preceding processes to the ones following. Pdf stellite alloy mixture hardfacing via laser cladding for control. Aug 12, 2011 the alloy stellite 6 has less tendency to crack than for example stellite 12, but only when multilayer technique is used. This article is based on what that research team has discovered. Stellite 3 angle bars, stellite 3 flanges, pipe fitting, steel pipe, heat exchanger and reducer, gasket, tee, pipe fitting, tube plate, have all specifications. Deposition characteristics of multitrack overlayby plasma. Electrode with high yield and extremely high deposition speed for overlay, repairs and joining of difficuittoweld steels. Oct 24, 2002 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. Hardfacing steel with nanostructured coatings of stellite.
The alloy currently most suited for cutting tools, for example, is stellite 100, because this alloy is quite hard, maintains a good cutting edge at high temperature, and resists hardening and annealing. Influence of yttrium additive on wear behavior of stellite 6 at elevated temperatures 25 54. Depending on how long the weld is and how its layed out, some cracking is usually inevitable with stellite 6 its normal. Hardfacing a standard term for a wearresistant weld overlay is commonly used for seat and guide surfaces on valve trim of all. 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. Due to its characteristics of wear resistance, corrosion resistance, oxidation resistance and high temperature resistance, it is. Dilution and wear properties of laser cladding stellite 6. The wear resistance of alloy 6b is due to the chemical composition and is not a product of heat treatment or other hardening mechanisms. Pdf influence of cutting parameters and tool wear on the surface. Most of the time, this material is stellite, a cobaltbase. The microstructure of stellite 6 contains hard m 7 c. Tensile strength is 758 mpa, yield stress is 655 mpa, youngs. Stellite definition of stellite by the free dictionary. The torch manipulation is generally automated and hence can achieve uniform overlays on complex parts.
Hardfacing alloys and processes for advanced ultra. Today, the hardening of sealing surfaces is performed by welding a material harder than the valve body material. This article provides an overview of work done to evaluate suitable alternatives to stellite 6. It may also contain tungsten or molybdenum and a small but important amount ofcarbon. Fracture toughness testing and toughening mechanisms of. Dilution, laser cladding, inconel 718, stellite 6 coating. Deposition of stellite 6 on nickel superalloy and mild. Recharge by welding a carbon steel valve with inconel625 825 overlay, cladding. Aug 16, 2011 seat overlay made of stellite 6 is possible but not recommended by us. Alternate stellite process material selection and properties. Stellite alloy is a range of cobaltchromium alloys designed for wear resistance. Repair of cracks in nozzle set of helicopter engine, repair of propeller shaft, etc.
The alloy stellite 6 has less tendency to crack than for example stellite 12, but only when multilayer technique is used. Bonding stellite 6 to alloy steel asme mechanical code. Stellite alloy, commonly known as cobaltbased alloy, is a kind of cemented. With many yeas production experience, strict control stellite 3 chemical composition and stellite 3 mechanical properties. 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. Introduction 1 stellite 6 is a very versatile material that is used for hardfacing of various component parts for applications requiring wear resistance cobaltbase rods 1982. The chemical composition of stellite 6 is given in table 3. Stellite alloy distributor in the usa a metal source, llc inventory consists of various stellite alloy grades in any size or form as indicated below. Failure analysis of surface stellite alloy overlayer on. Erosion test curves of stellite alloys 7 51 figure 215. Recharge by welding a carbon steel valve with inconel625 825overlay, cladding. Microstructure and wear behavior of stellite 6 cladding on.
How to avoid stellite 6 crackings american welding society. Date hs code description origin country port of discharge unit quantity value inr per unit inr sep 17 2016. Since the thickness is 5mm, we have to do 2 layers. Then we have to get 5mm thickness of cocra alloy overlay. However, when we finished the second layer and let it cool gradually wrapping the cone with. Oct 10, 20 the interface area in laser cladding, microstructures and mechanical properties of which determine the structural integrity of the laserdeposited coating, consists of two distinctive zones.
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