- Big 50
With the acquisition of UK-based Deloro Stellite, Kennametal´s newest business unit, Kennametal StelliteTM, brings industry-leading wear-resistant solutions in alloys-based science, cast and machined components, hardfacing materials, and coating services that excel in wear-resistance in extreme temperatures and applications.
A global manufacturer and provider of alloy-based critical-wear solutions for extreme environments involving high temperature, corrosion, and abrasion, Kennametal Stellite employs approximately 1,300 people across seven primary operating facilities globally, including locations in the U.S., Canada, Germany, Italy, India and China. It combines proprietary metal alloys and materials expertise with specialized engineering design and fabrication capabilities to deliver value-added, tailored wear solutions for customers in oil and natural gas, power generation, automotive, aerospace/defense, medical/dental, and process and general engineering segments.
"Deloro Stellite has a longstanding history of providing exceptional value to customers in demanding environments and we are pleased they have agreed to join the Kennametal team," commented Carlos Cardoso, Kennametal Chairman, President and CEO. "The addition of this world-class surface technology and materials science expertise will enhance the range of productivity solutions provided to our customers in extreme wear environments."
Stellite is recognized around the world as being synonymous with cobalt-based alloys. In 1907, Deloro Smelting and Refining Company was set up by Michael John O'Brien and Elwood Haynes in the small Canadian cobalt mining village of Deloro. When Haynes left in 1912 to focus on nickel-based components, O'Brien formed Deloro Stellite to produce cobalt-based Stellite alloys.
Stellite products include:
-StelliteTM: Cobalt-based alloys with the best ´all-round´ wear properties. They combine exceptional wear and heat resistance and are used across a wide range of applications.
-DeloroTM: Nickel-based alloys which cover a broad range of hardness'. They tend to have lower melting points which make well suited for powder welding or spray and fuse.
-TribaloyTM: Intermetallic-phase alloys which can be either nickel- or cobalt-based. They perform exceptionally well in metal-to-metal wear at high temperatures.
-NistelleTM: Nickel-based, corrosion-resistant, high-melting-point alloys. Developed for protection against aggressive chemicals or other corrosive media.
-StelcarTM: Nickel or cobalt-based alloys with carbide particles. Only available in powder form for coating applications.
-Jet KoteTM: Carbide and metal combination powders specifically designed for thermal spraying.
-DelcromeTM: Iron-based alloys designed for abrasive wear resistance at lower temperatures.
-DuraStellTM: High-performance metal claddings for use in critical applications where corrosion and wear limit part life and reliability. A metallurgical bond is formed with the substrate material, making the process of particular value where conventional alloys and application methods cause excessive part distortion or degradation of high-performance base metals.
Kennametal Stellite also provides such value-added services as rapid product development of cast components, final assembly of power generation steam valves, fully machined parts, and coating services. Parts are produced through different processes such as investment casting and finish machining, and are custom-engineered to meet individual customer needs. In addition, Kennametal Stellite offers its expertise and experience in coating services in the form of HVOF (High-Velocity Oxy Fuel) coatings and weld hardfacings.
Keeping Power Flowing
Recently, a major US-based power company experienced new challenges with their supercritical steam drain and vent lines in one of their plants. Kennametal Stellite was engaged by a large OEM of severe-service valves to resolve the issue. MSBVs (metal-seated ball valves) are being used on drain and vent lines to extract large quantity of condensate during plant startup in order to get dry superheated steam rapidly. MSBVs must remain steam-tight to prevent energy loss and maximize plant efficiency. This particular fossil-fuel power station runs continuously from May to October due to high power demand to run air-conditioning systems. For the balance of the year, the plant only runs when the demand called for more power during peak usage times. Every time the plant shuts down or starts up, MSBVs are operated and exposed to supercritical steam operating conditions.
The MSBVs in question were of a floating ball design with a fixed seat, manufactured from forged Inconel® 718 PH and coated with a HVOF 80% Cr3C2 + 20% NiCr coating. This coating failed after 1 year and less than 500 mechanical cycles in service on balls exposed to supercritical steam, with deterioration extending to regions where there is no contact between ball and seats. Visual examination of damaged components revealed minor frictional wear and typical stress/fatigue pattern.
Testing revealed the dominant failure mechanism to be coating embrittlement due to chrome carbide precipitation in-service across coating binder. Brand new samples were produced with three new Kennametal Stellite coatings. A battery of tests was performed to assess their behavior for this specific application.
Once the cause was known, further tests revealed a spray- and-fuse NiWCrBSi coating more suitable to support high bearing load when facing thermal shock. This coating is less sensitive to ageing at high temperatures and therefore more durable under these very specific conditions.
An enhanced HVOF coating, produced from a mixed (W,Cr)C and WC carbides in a nickel matrix, also emerged successful from the tests. While it showed similar ductility compared to the original HVOF Cr3C2-NiCr coating, it consistently provided longer in-service life in service under 540 ºC (1,000 ºF).
Armed with these new coating technologies, new valves were installed in the plant. They have worked flawlessly for the past year. As a result, the valve manufacturer´s MSBV line for the power industry now features two coatings: one designed for regular service - HVOF (W,Cr)C-Ni and one specially designed for applications involving severe thermal shocks - S&F NiWCrBSi.
For more information, visit http://stellite.com
Kennametal Inc. (NYSE: KMT) delivers productivity to customers seeking peak performance in demanding environments by providing innovative custom and standard wear-resistant solutions. This proven productivity is enabled through our advanced materials sciences and application knowledge. Our commitment to a sustainable environment provides additional value to our customers. Companies operating in everything from airframes to coal mining, from engines to oil wells and from turbochargers to construction recognize Kennametal for extraordinary contributions to their value chains. In fiscal year 2012, customers bought approximately $3 billion of Kennametal products and services - delivered by our approximately 13,000 talented employees doing business in more than 60 countries - with more than 50 percent of these revenues coming from outside North America. Visit us at www.kennametal.com