Hightemperature hardness and wear resistance of stellite alloys. Stellite alloys are often used as a weld hardfacing on valves, spindles, and other. Either in an electrode or bare wire for oxyacety or gtaw. The parts treated with this equipment may be referred to as stellite parts as in stellite exhaust valves. Longwear alloys ltd assumes no liability for errors or omissions. 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. This paper presents results of specimen tests addressing this issue, with emphasis on the following. 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. In stellite alloys this generally has the following effects. View detailed import data, price, monthly trends, major importing countries, major ports of stellite 6 under hs code 81052010. Gas tungsten arc welding gtaw process was used to clad the samples with stellite 6. 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. Pdf delamination failures of stellite hardfacing in power.
This course includes an overview of the various types of wireless 802. Overlay repair of dissimilar metal alloy 82182 welds with. 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. 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. 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. Effect of two different energy inputs for laser cladding of stellite 6. Cracking has been observed in valve components at the stellitesteel. 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. Stellite is a registered trade mark of deloro stellite. Stellite 6 overlay on the disk contact surfaces of a dual plate check valve. A buttressed layer to be on the safeside is given usual preheat to 250 deg cent and then also pwht for additional application of stellite 6 alloy by gtaw process. This article provides an overview of work done to evaluate suitable alternatives to stellite 6. Finally, results showed that microcrack initiation was the main.
Then we have to get 5mm thickness of cocra alloy overlay. Never attempt without pwht on a welded low alloy steel with stellite 6 application. 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. Aug 15, 20 the carbides present in the cocrwbased stellite alloys are of chromiumrich m 7 c 3 type. We are able to offer hard facing overlay of stainless steel 316, duplex and super duplex with stellite 6. Stellite used to be a part of union carbide and sold to stody, to produce their alloys for hardfacing. As such, they provide much better ductility and resistance to cracking than alloy 6. However, in larger and more complex parts, cracking can occur from the. 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.
Since the thickness is 5mm, we have to do 2 layers. The sequence of the primary welding process and the following secondary processes of machining, and heat treatment has been modelled to predict the residual. Is stellite 6 an acceptable substitute for 316 ss in low temp. Stellite 6 can be successfully welded when high levels of preheat are applied.
Stellite is a registered trade mark of deloro stellite this is personal experience from the my time in the electric power industry stellite 6 typically is applied only in shop and. Stellite definition of stellite by the free dictionary. This article is based on what that research team has discovered. Neither of us have any handson experience to back it up, but we both feel like h should hold up pretty well for the application if its properly hardened. Wear characteristic of stellite 6 alloy hardfacing layer by plasma. Came in next morning and as i continued to overlay next set of flats i heard some tings. The results showed less cracking and pore development for stellite 6 coatings applied to. Longwear certified air melt ingots alloy cross reference index cobalt based alloys. Stellite 21 is much less prone to cracking in our experience when we can talk the customer into it over 6 we do it every time.
The results showed less cracking and pore development for stellite 6 coatings applied to the p22 steel substrate. Stellite 6b cobalt alloy steel cobaltchromium alloy. Evaluation of microstructure and mechanical properties at the. It is able to retain these same properties at elevated temperatures.
The cocrw system alloy retains its hardness at elevated temperatures and is especially effective for wear applications at high temperatures or in a corrosive environment, and are widely used as a wear, corrosion, and heatresistant material 43. Two layers of stellite 6 were coated for a maximum thickness of 6 mm or higher. The different process steps are coupled in order to transfer the residual conditions from preceding processes to the ones following. Cobalt alloy 6b stellite 6b ams 5894 aircraft materials.
Fisrtly, we had a 3mm thickness of 309mol overlay with fcaw. A comparative study for wear resistant of stellite 6. Seat overlay made of stellite 6 is possible but not recommended by us. 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. A different company who buys the stellite equipment and uses it to manufacture hard.
It may also contain tungsten or molybdenum and a small but important amount ofcarbon. Recharge by welding a carbon steel valve with inconel625 825 overlay, cladding. Pta hardfacing of stellite 6 on stainless steel has been carried out in plasma transferred arc pta welding machine since it is a semiautomated process. Most crackings are perpendicular to the welding seam.
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. China stellite 6 hardfacing cobalt welding powders for. Dear friends we have one order from my client to supply onoff valve from size 4 up to 24 inch. 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. Import data and price of stellite 6 under hs code 81052010. 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. Stellite 6, stellite 6 powder, hardfacing cobalt welding powders manufacturer supplier in china, offering stellite 6 hardfacing cobalt welding powders for valves, stellite 12 bishilite 12 cobalt. The interface area in laser cladding, microstructures and mechanical properties of which determine the structural integrity of the laserdeposited coating, consists of two. Proprietary crackresistant alloy specially developed for. Pwht is also required to reduce tensile stresses as much as possible for a hard facing stellite 6 application.
Argon gas was used as the shielding gas as well as the medium for generation of plasma in pta process. Stellite alloys chemical composition, mechanical properties. We took the method of smaw with the stick electrode of stellite 6. The top countries of supplier is china, from which the percentage of stellite 6 welding rod supply is 100% respectively. 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. This is a better and more fool proof approach even for buttressed inconel 625 layer welding done before application of stellite 6 or stellite 21. Can duplex stainless steels be hardfaced without adversely affecting the base material properties. Aug 04, 2017 laser cladding with stellite 21 of new shaft duration.
Also we can apply other materials such as stellite 6 or 12 or nickel ni 100%. Stellite 6 welds pretty clean unless it gets oxidized and then the puddle gets sluggish. The hot hardness of stellite 6 weld overlays drops off sharply as iron. Microstructure evolution and failure behavior of stellite 6. I know that stellite can be a bit difficult to deposit and the method of deposition can have a significant influence on the overlay cracking. This was overlayed with stellite 6 at a location that one would expect to be overlayed. Evaluation of microstructure and mechanical properties at. Alternate stellite process material selection and properties.
In firearms history, stellite was first used starting around world war ii to line the first 12 inches of barrel in the m2hb in order to help mitigate barrel throat erosion. Hard facing hf and corrosionresistancealloy cra with hot wire, materials. Bonding stellite 6 to alloy steel asme mechanical code. Stellite exhibits unparalleled hardness and toughness as well as an extremely high melting point due to its cobalt and chromium content. How to avoid stellite 6 crackings american welding society.
We clearly mention that it is not possible to perform a stellite 6 completely free of hair cracks. Pdf delamination failures of stellite hardfacing in. Dear experts, we are doing stellite welding in ptaw process. After cladding, samples were cooled in air and finally subjected to precipitation hardening treatment at 480 c for 1 h. The dilution region is the region where melted substrate forms a mixture with coating material and possesses microstructure similar to the coating. Implementation of stainless steel buffer layer for reducing crack.
Laser cladding, hvof, plasma spraying, stellite 6 coating, friction and wear, nickel alloy. 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. When we finished the first stellite 6 layer, there is no cracking found. Most often these cracks are transverse cross cracks, which are very beneficial to relieve the residual stress in the weld bead. 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. 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. 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. 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 field with only. In this chapter, the hardfacing of gate valves, and measurement of bead geometry and residual stresses induced are detailed.
Initial looks at the overlay suggests that the stellite hadnt bonded with parent at all. Introduction 1 stellite 6 is a very versatile material that is used for hardfacing of. Influence of cutting parameters and tool wear on the surface. Ref 8 examined the dry milling machinability of stellite 6 alloy layers using. Pdf influence of cutting parameters and tool wear on the surface.
The gtaw process parameters are provided in table 2. Impact wear resistance of stellite 6 hardfaced valve seats with. Stellite alloy is a range of cobaltchromium alloys designed for wear resistance. Hightemperature hardness and wear resistance of stellite. It is easily deposited by a number of methods but you do have to be careful about contamination from sulphur or phosphorus. View detailed import data, price, monthly trends, major importing countries, major ports of stellite 6 wire. 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. Laser cladding with stellite 21 of new shaft duration. This alloy also has higher hot hardness and resists galling like all stellite alloys when mated with another stellite alloy. A wide variety of stellite 6 welding rod options are available to you, there are 253 suppliers who sells stellite 6 welding rod on, mainly located in asia. Microstructure and wear behavior of stellite 6 cladding on. Plasma transferred arc welding of stellite 6 alloy on.
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. In addition to the above specifications we can offer manufacturing to customer individual requirements and specifications including toll melting and remelting. Hardfacing alloys and processes for advanced ultrasupercritical. Wear resistant cocrw cobalt 6b is a cobalt based chromium, tungsten alloy for wear environments where seizing, galling and abrasion are present. Stellite 6b high performance cobalt chrome material properties in addition to stellites outstanding corrosion and wear resistance, tough and durable cobalt chromium alloy steel can be utilized at extreme temperature variables. Whats the grade of stellite to be depositedstellite is a brand originated from cabot corporation and now with delloro stellite, and it comes in various alloy grades such as. Room and high temperature wear behaviors of nickel and cobalt base weld overlay. A comparative study for wear resistant of stellite 6 coatings. It may also contain tungsten or molybdenum and a small but important. Even though these alloys are both inherently softer than alloy 6, they still provide excellent resistance to sliding wear, galling, liquid flow erosion and cavitation damage because they are cobaltbased. This type of cracking will not affect the wear resistance.
Stellite 6 welding rods hai stellite 6 rod is cobalt base rod. The material is also resistant to erosion and most. A cobaltbased alloy, stellite 6, was deposited on the seat face of control. Delamination failures of stellite hardfacing in power plants. Stellite 6 is a cobase wear resistant alloy containing 1% c, 27% cr, 4. It looks like most of the sections can be remade for the same or less money as itd cost to attempt the stellite overlay and attendant machining. Stellite overlay on duplex stainless welding, bonding. Kennametal, velan and carleton university formed a research team to evaluate new hardfacing alloys and application processes for advanced ultrasupercritical applications. Status of stellite 6 friction testing unt digital library. The issue of whether hardfacing adversely affects the properties of duplex. Hardfacing a standard term for a wearresistant weld overlay is commonly.
The way we produce a stellite coating is by taking cobalt 6 powder, for example, and applying it to a roughmachined round andor flat metal surface using the plasma transferred arc pta. Stellite is a nonmagnetic alloy which contains a variety of different metal components with the main elements being cobalt and chromium. These hardfacing layers are applied as an overlay onto a steel substrate. Stellite was a major improvement in the production of poppet valves and valve seats for the valves, particularly exhaust valves, of internal combustion engines. 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. Stellite 6 hard facing weld overlay at renown oil and gas, we continuously increase our range of prequalified procedures to improve the variety of weld overlay solutions available to our customers. Since most hardfacing deposits have nearly no ductility, the welds will crack. The microstructure of stellite 6 contains hard m 7 c. Application is highly sour h2s and co2 and water and also a little cl.
Hardfacing alloys and processes for advanced ultra. The results showed less cracking and pore development for stellite 6 coatings applied. Stellite is a family of completely nonmagnetic and corrosionresistant cobalt alloys of various compositions that have been optimised for different uses. Microstructure and wear behavior of stellite 6 cladding on 17. If stellite 6 is an overlay shouldnt the valve manufacturers specify what the underlying material is. 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. Ct52 is a cobalt based alloy, which provides excellent resistance to wear, galling, and corrosion. What is the best gas to use when doing a stellite overlay on 316ss.
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