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. A comparative study for wear resistant of stellite 6 coatings. The disadvantage of this process is that the stellite layer will often crack when there is a change in temperature, which will not occur with sprayed stellite. Preheating of substrate could reduce thistendency of cracking. The oxidized netlike m 23 c 6 eutectic carbides and the interface of. 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. The different process steps are coupled in order to transfer the residual conditions from preceding processes to the ones following. The effect of dilution on haz liquation cracking in ptaw. In further studies, the mechanism of thermal cracking of stellite 6 coating was revealed. Pdf stellite alloy mixture hardfacing via laser cladding for control. Pdf delamination failures of stellite hardfacing in. 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. Hightemperature hardness and wear resistance of stellite alloys.
Chrome carbide stellite usually craze crack not considered detrimental to wear resistance. Never attempt without pwht on a welded low alloy steel with stellite 6 application. Deposit thickness avoid excessive buildup of hardfacing deposits or they may crack and break off rapidly in service. Two layers of stellite 6 were coated for a maximum thickness of 6 mm or higher. Stellite alloy is a range of cobaltchromium alloys designed for wear resistance. Co acted as pathways to promote crack propagation during thermal fatigue. A metal source, llc stellite alloysstellite alloys. Bonding stellite 6 to alloy steel asme mechanical code. Welded joints can have greater susceptibility to cracking than. For small, simple parts, cracking is not a usually a problem.
Recharge by welding a carbon steel valve with inconel625 825 overlay, cladding. Crack repairs in stellite may highlight cracking in base material, with propagation through the overlay. 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. Influence of yttrium additive on wear behavior of stellite 6 at elevated temperatures 25 54. 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. Q235 mild steel was used as substrate, and stellite 6 alloys were welded by plasma transferred arc welding ptaw. Is it true that stellite 6 hf will leave hairline cracks on the surfece. Tribological test was conducted to characterize the wear property. The chemical composition of stellite 6 is given in table 3.
Cracking resistance of stellite 6 clad austenitic stainless steel components can be greatly enhanced by providing smooth composition gradient across substrateclad interface. Cobalt alloy 6b stellite 6b ams 5894 aircraft materials. In practice, however, an automated process is a much more efficient way to weld overlay a complex surface. Pdf delamination failures of stellite hardfacing in power. Stellite 6, 12, 720 wc composites carbon steels 1026, 4, 1018. Hardfacing a standard term for a wearresistant weld overlay is commonly used for seat and guide surfaces on valve trim of all styles. 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. Pdf influence of cutting parameters and tool wear on the surface.
Stellite is a family of completely nonmagnetic and corrosionresistant cobalt alloys of various compositions that have been optimised for different uses. How to control check cracking and use to your advantage. Pdf deposition of stellite 6 hard facing overlay on f55 super. Since the thickness is 5mm, we have to do 2 layers.
Dry sliding wear map for stellite 6 against a wcco 9010 disc 12 49 figure 214. This article provides an overview of work done to evaluate suitable alternatives to stellite 6. The results showed less cracking and pore development for stellite 6 coatings applied to. Hightemperature hardness and wear resistance of stellite. Also we can apply other materials such as stellite 6 or 12 or nickel ni 100%. Preheating of substrate could reduce thistendency of cracking but. Weld overlay coating, also known as hardfacing, is a method which involves application of hard and wear. Have sufficient ferrite present to prevent cracking minimum fn of 3. Stellite is a nonmagnetic alloy which contains a variety of different metal components with the main elements being cobalt and chromium. For comparison with conventional hardfacing techniques, a plasma transferred arc pta method was chosen for parallel experiments in this study. With ultimet alloy, cracking of the overlay is not a consideration, and multiple layers may be applied, with. 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. Deposition of stellite 6 on nickel superalloy and mild steel.
The microstructure of stellite 6 contains hard m7c3 carbides in interdendritic regions of the. How to make a paracord bullwhip like indiana jones. Stellite 6b hpa cobalt 6b uns r30016 high performance. Thermal fatigue cracks had already traversed the 2 mm thick stellite 6 surface layer entirely.
Laser assisted deposition of graded overlay of stellite 6. Review hardfacing steel with nanostructured coatings of stellite 6 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. 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. Eutectic carbides in stellite alloys are replaced in this novel alloy with. Surface preparation badly cracked, deformed or work hardened surfaces should be removed by grinding, machining or carbonarc gouging. We are welding a 309ss butter layer and a stellite 6 overlay. 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 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. 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.
In stellite alloys this generally has the following effects. Impact wear resistance of stellite 6 hardfaced valve seats. Stellite definition of stellite by the free dictionary. 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. 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. If you need a bearing on a shaft, build it up with 308, and then turn down until you are about 0. This article is based on what that research team has discovered. Put two 5mm washers into the hole, now the bolt can be tightened without cracking the protective plastic overlay.
Dear friends we have one order from my client to supply onoff valve from size 4 up to 24 inch. Most crackings are perpendicular to the welding seam. The effect of dilution on haz liquation cracking in ptaw nibase superalloys overlay deposit byoung hyun yoon, yong soo ahn 1and chang hee lee. 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. Stellite 6 on super duplex welding processes in theory, the welding processes used can be manual. The wear test results showed that the weight stellite 6 coating, loss for the c friction and wear, nickel superalloy and mild steel. To see matwebs complete data sheet for this material including material property data, metal compositions, material suppliers, etc, please click the button below. 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. This article presents development of graded overlay of stellite 6 on aisi 304 stainless steel substrate using 2.
Further, the stellite coating on mild steel was laser cladding, significantly harder than that deposited on the superalloy. With ultimet alloy, cracking of the overlay is not a consideration, and multiple layers may be applied, with little or no preheat. A comparative study for wear resistant of stellite 6. Laser cladding, hvof, plasma spraying, stellite 6 coating, friction and wear, nickel alloy. Stellite 6 welds pretty clean unless it gets oxidized and then the puddle gets sluggish. Stellite 6 will also have a good resistance to impact and cavitation erosion. The workhorse hardfacing alloy in the valve industry is generically known as alloy 6, although it is often called stellite 6. Components are often hardfaced with stellite through a welding process. Stellite alloys chemical composition, mechanical properties.
There is an alternative to the costly practice of removal and replacement of failed pavement sections prior to an asphalt overlay. Erosion test curves of stellite alloys 7 51 figure 215. These results were similar to that obtained by tang and tunthawiroon 19, 20. Stellite 6 overlay on the disk contact surfaces of a dual plate check valve. This page displays only the text of a material data sheet. Slightly increased preheat, and tight stringer beads to deposit stellite 6 directly on top of low alloy steel. 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. Wear resistant cocrw cobalt 6b is a cobalt based chromium, tungsten alloy for wear environments where seizing, galling and abrasion are present. Unlike methods such as weld overlay, thermal sprays, and traditional cladding, the kennametal ultraflex treatment. Wear characteristic of stellite 6 alloy hardfacing layer. Stellite 21 can be supplied as steel plate sheet, round steel bar, steel tubepipe, steel stripe, steel billet, steel ingot, steel wire rods. Get your very own tkor official tshirt, only available for a short period of time. It may also contain tungsten or molybdenum and a small but important. A buttressed nonferritic grade austenitic base alloy with buttressed inconel layer.
If you try welding alloy 6 to something else, its probably going to crack. 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. Apart from economics, other factors that determine the weld process include access, weld position and the alloy applied. In addition to the above specifications we can offer manufacturing to customer individual requirements and specifications including toll melting and remelting. Tribocorrosion experiments were performed by using a pinondisc tribometer under controlled electrochemical conditions in liohh3bo3 solutions similar to coolant water. Longwear certified air melt ingots alloy cross reference index cobalt based alloys. Trim material 1 f6 cr % chromium % chromium % chromium x 2 304 188 crni type 304 stainless steel type 304 stainless steel type 304 stainless steel x, y, z e 2h d 304 hardfaced stellite 6 stellite 6 type 304 stainless steel x, y, z f type 304 stainless steel stellite 6 5 hardfaced co cra stellite 6 stellite 6 % chromium x, y. Microstructure evolution and failure behavior of stellite 6. Hardfacing steel with nanostructured coatings of stellite. Concrete rehabilitation products polyguard highway division. 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. Alternate stellite process material selection and properties. The laserclad layers, which consisted of refined solidification structures, were characterized by increased hardness and. Aug 15, 20 the carbides present in the cocrwbased stellite alloys are of chromiumrich m 7 c 3 type.
Developing the ductility and thermal fatigue cracking. On this project, the facility owner, who had planned removal and replacement of pavement sections, heard that he could save a significant amount on the project cost by applying polyguard nw75 underseal to all joints and cracks. This alloy also has higher hot hardness and resists galling like all stellite alloys when mated with another stellite alloy. Hardfacing stellite 6 on 309ss welding tips and tricks. Nace mr0175 certified user my reading 6 by charlie chong issuu. Due to the high cost of stellite when i got to the end of a rod id let the rod stay in the puddle then fuse my next rod onto the last and keep on trucking.
Plasma transferred arc welding of stellite 6 alloy on. Stellite 6b cobalt alloy steel cobaltchromium alloy. Check availability with our sales department by submitting your inquiry below to see if a metal source, llc can provide your stellite alloy metal requir. A cobaltbased alloy, stellite 6, was deposited on the seat face of control valves using a coaxial laser cladding process. Effect of welding variables on cracking in cobaltbased sma. Plastic overlay not shown in this video, but if you are here you know what you are. Hardfacing steel with nanostructured coatings of stellite6. But the alloy 21 bufferlayer hardness, which ranged from 39 to 70 rockwell c most readings were above 50, was well outside the range expected for this material. Delamination failures of stellite hardfacing in power. Instead of using stellite 6 overlay on smaller sizes 22cr duplex components e.
Longwear alloys ltd assumes no liability for errors or omissions. These types should not be used where cracking is undesirable, eg. What is the best gas to use when doing a stellite overlay on 316ss. When we finished the first stellite 6 layer, there is no cracking found. Stellite6, hardfacing, hardness, impact, volume fraction, tig, pta. Issues such as cracking along the weld line, hydrogeninduced cracking, and porosity, among others, have been reported. Many components require the application of additional layers to. 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. Chromium is added to form carbides and to provide strength to the cobalt. Hardfacing alloys and processes for advanced ultrasupercritical. It is easily deposited by a number of methods but you do have to be careful about contamination from sulphur or phosphorus. 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. It is a mixture of cobalt and other elements like nickel, chromium, tungsten, carbon and molybdenum.
Grade 91 and alloy 6 had hardness values within their expectedranges. Stellite 6 can be successfully welded when high levels of preheat are applied. The material is also resistant to erosion and most. How to avoid stellite 6 crackings american welding society. Application is highly sour h2s and co2 and water and also a little cl. Then let cool in insulation for a day and a half or so. 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. Kennametal, velan and carleton university formed a research team to evaluate new hardfacing alloys and application processes for advanced ultrasupercritical applications.
If thick deposits are needed, use the appropriate buildup materials before hardfacing. 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. Deloro stellite says the hardness of its stellite 21 typically is 27 hrc and can workharden up to 40 hrc. 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 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. Seawater applications are not suitable for stellite 6, as it is at high risk of cracking in that environment. Jan 04, 2016 cracking knuckles joints hey guys so today i will be doing a video on knuckle cracking and showing you how i crack my knuckles joints as well as a little bit of research about joint and or. Though stellite 6 exhibits an excellent oxidation resistance at high temperature, its initial cost is high and periodic repairs add signi.
Stellite is a registered trade mark of deloro stellite. Product forms ultimet alloy is available in most common wrought product forms. 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. In this chapter, the hardfacing of gate valves, and measurement of bead geometry and residual stresses induced are detailed.
Delamination failures of stellite hardfacing in power plants. Can any one suggest which is the best wheel to use. 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. Argon gas was used as the shielding gas as well as the medium for generation of plasma in pta process. 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. Stellite 6 coatings applied to the mild steel ms substrate. The microstructure of stellite 6 contains hard m 7 c.
Stellite 6 is a cobase wear resistant alloy containing 1% c, 27% cr, 4. Ep2780485a1 alloy for high temperature tooling applications. Its not cracking but just small little holes, looks like. Gandy2 in recent years, several incidents of cracking and failures have been observed in stellite. I have used stellite 6 quite a bit in the last few months.
Hard facing hf and corrosionresistancealloy cra with hot wire, materials. Came in next morning and as i continued to overlay next set of flats i heard some tings. Stellite 21 steel chemical composition, metal properties. Microstructure and wear behavior of stellite 6 cladding on 17. I preheat the parts spools 4 716 6 716 diameter 5 10 long to f and keep it inbetween 700 760f while welding. Metallurgical aspects of welding stellite 12 to type 316l. 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.
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