HPA 6B

Chemistry*

Typical Inventory

Round Bar, Plate, Forge, Billet, Ingot

Applications

Applications for alloy 6B include half sleeves and half bushings in screw conveyors, tile making machines, rock crushing rollers, and cement and steel mill equipment. Alloy 6B is well suited for valve parts, pump plungers shafting, and sleeves.

Wrought alloy 6B offers the ductility, fatigue resistance, and toughness of a hot worked microstructure with the heat corrosion and wear resistance of a cobalt based alloy. Some common applications are steam turbine erosion shields, chain saw guide bars, high temperature bearings, furnace fan blades, valve stems, food processing equipment, needle valves, centrifuge liners, hot extrusion dies, forming dies, nozzles, extruder screws, and many other miscellaneous wear surfaces.

General Data

• Hot Worked, Aged, Air Cooled
• Density 0.303 lb/in³
• Specific Heat (@ 72 °F) 0.101 Btu/lb-°F
• Thermal Conductivity (32 to 212 °F)
  103 Btu-in./sq. ft.-hr.-°F
• Electrical Resistivity (68 °F)
  546 Ohms/ cir mil ft
• Melting Range 2310 to 2470 °F
• Electrical Conductivity compared to Copper 1.90%
• Reflecting Power 57 - 70%
• Mean Coefficient of Thermal Expansion
  32-212°F 7.7 microinches/in.°F

  32-932°F 8.3 microinches/in.°F

  32-1472°F 9.1 microinches/in.°F

  32-1832°F 9.7 microinches/in.°F

Mechanical Properties

The typical properties listed can usually be provided in rounds, sheet, strip, plate, & custom forgings. We have the equipment to produce small quantities in special sizes to meet our customers’ specific needs. The table below shows Stellite's minimum Mechanical Properties of Alloy 6B per AMS 5894. For most common forms and exceptions, check out the datasheet linked underneath the table.

UTS = Ultimate Tensile Strength, YS = Yield Strength

Common Specifications

Note that the specifications listed are common for this alloy but are for reference only and may be specific to a certain form. The specifications listed are not comprehensive nor indicative of any edition, revision, or similar such as an amendment. Please, reach out to our sales department to request the Material Test Report (MTR) or to confirm your required specifications.

Fusion Welding

Alloy 6B can be welded by gas tungsten-arc (TIG) with an argon flow of 25 CFH, gas metal-arc (MIG), shielded metal-arc (coated electrode), and oxy-acetylene in this order of preference. The oxy-acetylene method should be used with discretion and care in that alloy 6B will “boil” during welding which may cause porosity. Use a 3X reduction flame to minimize oxidation, penetration, and inter-alloying.

Alloy 6B should be preheated and maintained at 1000ºF minimum to prevent cracking during welding and then still air cooled. Fixturing which would chill the weld rapidly should not be used. Standard weld joints are recommended. Alloy No. 25 filler metal is recommended for joining alloy 6B to softer materials such as carbon steel or stainless steel, while the harder cobalt base filler metals such as No. 6 and No. 21 are recommended for joining alloy 6B to itself, especially if wear resistance is required in the weld areas. In the latter case, No. 25 may be used for the root passes and then be overlayed with the harder materials. Gas shielding of the root side of the gas tungsten-arc weldments is not mandatory but it is recommended in order to improve weld penetration.

Brazing

Alloy 6B is readily joined to other materials by brazing. All forms of surface dirt such as paint, ink, oil, chemical residues, etc., must be removed from the mating parts by etching, solvent scrubbing, degreasing, or other means. In addition, fluxing will be required during torch brazing operations when using silver brazing filler metal, to help clean the joint and allow the filler metal to flow more freely over the mating surfaces. Generously brush joining areas with brazing flux prior to heating. When torch or induction brazing, as soon as the brazing filler melts, the source of heat should be removed and the parts positioned. The assembly should then be pressed together to squeeze out the excess flux and still air-cooled. The parts should not be quenched.

Other brazing filler metals (i.e., gold, palladium, or nickel-base alloys) are satisfactory for joining alloy 6B. Brazing filler metal selection depends on the service conditions expected.

A close fit of the mating surfaces is recommended. The finished joints will have greater strength if the filler metal is very thin, generally 0.001- 0.005” thick.

Brazing, with high-temperature filler materials, is generally performed in a furnace. Induction and resistance heating with salt-bath and metal-bath dip brazing have limited application. Vacuum furnaces held at less than one micron pressure or controlled atmosphere furnaces, having adequate moisture control at brazing temperatures, produce the most satisfactory results. Controlled atmospheres such as hydrogen or cracked ammonia are suitable for brazing alloy 6B base materials.

Machining

Alloy 6BH is generally machined with tungsten carbide tooling, and will produce a finish of about 200-300 RMS. Carbide inserts are used with a 5° (0.9 rad.) negative tool holder and a 30° (0.52 rad.) or 45° (0.79 rad.) lead angle. Tools for facing or boring are essentially the same except for greater clearances where needed. For best results in drilling, the drill web should be kept thin. Screw machine length, carbide tipped drills should be used. In reaming, a 45° (0.79 rad.) cutting lead angle should be used. High speed taps are not recommended for Alloy 6BH but threads can be produced by EDM techniques. For better surface finish, this alloy should be ground.

6BH is ground to obtain close tolerances with excellent finish properties. Do not quench dry ground material as it may cause surface imperfections.

Terms and Conditions

References

Stellite® is a registered trademark of Kennametal Inc..

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