Hardfacing with Tungsten Carbide for Wear Resistance

Hardfacing is a welding process of build-up deposits of alloys to resist corrosion, abrasion, high temperature, or impact.  Hardfacing increases a part’s service life and can thus directly affect machinery efficiency and reduce the amount of equipment that is scrapped.  When addressing wear resistance needs, high-deposit hardness material does not always provide the best overall wear resistance.  Rather, when choosing a hardfacing alloy for wear resistance, the presence of carbides must be considered in addition to hardness properties.

Alloys that are typically used for hardfacing include iron-base alloys, cobalt-base alloys, nickel-base alloys, and tungsten carbides.  Tungsten carbide is one of the most superior metal-to-earth abrasion resistant hardfacing materials.  When compared to a chromium carbide overlay, a machine part hardfaced with tungsten carbide can experience a 3 to 5 time increase in service performance.

Polymet offers two tungsten carbide wires, POLYTUNG NiBWC, with a Ni-B-Si-matrix, and POLYTUNG NiCrBWC, with a Ni-Cr-B-Si-matrix.  The matrix is responsible for roughly 35-40% of the deposit alloy while the tungsten carbide consists of the remaining 60% of the deposit alloy.  Both of these alloys have a macro crystalline carbide structure.  Some of the applications that are hardfaced using Polymet’s POLYTUNG wires are dredge cutter heads & teeth, ID elbows & pipes, oil tool bits, and bucket teeth.  Hardfacing with tungsten carbide materials can be applied to industries such as mining, oil & gas, and construction.

Introducing PMET 906B BAR – Stellite 6b Equivalent – AMS 5894

Polymet Corporation continually strives to utilize it’s unique extrusion technology to introduce high quality cobalt based products to the market place for superior performance in harsh environments.  Over the past two years Polymet has worked to develop an equivalent to Stellite 6b bar to offer the industry.  We are now pleased to offer PMET 906B as a standard product.

PMET 906B is a cobalt based chromium, tungsten alloy suitable for extreme heat, wear and abrasion conditions.  PMET 906B is non-galling, has a low coefficient of friction, retains high hardness at high temperatures, recovers full hardness after 2000° F exposure and has excellent resistance to corrosion, oxidation, thermal shock and heat checking.  PMET 906B performs excellent in wear environments where seizing, galling, abrasion and corrosion are present either alone or in combination with each other, making  the alloy very versatile.  Unlike other cobalt based cast alloys, PMET 906B is hot forged resulting in a refined wrought grain structure that gives the alloy added strength and ductility, all while maintaining the wear and heat corrosion resistance inherent in cobalt based materials.

APPLICATIONS
Steam Turbine Erosion Shields	Turbine Engine Nozzle Fuel Injectors	Valve Stems
High Temperature Bearings	Chain Saw Guide Bars	Furnace Fan Blades
Needle Valves	Centrifuge Liners	Hot Extrusion Dies
Extruder Screws	Motor Shafts, Bushings, Sleeves, Stems	Tile Making Machine Bushings
Rock Crushing Roller 1/2 Bushings	Cement /Steel Mill Bushings, Sleeves	Petrochemical Components

*Stellite is a registered trade mark of Deloro Stellite.