HPAlloys Cobalt 6BH * CoCrW * Uns
High
Performance Cobalt
Base Wear Alloy

HPAlloy Cobalt 6BH

March 2001 Volume 6, Issue 2
HPAlloys
Cobalt 6BH
Product
Description 		Cobalt 6BH CoCrW
UNS R30016
Surpasses 6K with better ductility with same good hardness Cobalt 6BH is the same composition of Cobalt 6B, except the material is hot rolled and then age hardened.
The direct age-hardening after hot rolling provides the maximum hardness and wear resistance. The advantages this creates are increased wear life, retained edge characteristics, and increased hardness. These properties are in addition to the galling and seizing resistance of the regular Cobalt 6B. Cobalt 6BH is known in the industry as a metal that retains its cutting edge. The economic advantages are in its long wear time, less down time, and fewer replacements.
Chemistry
Co Cr W Mo Ni Mn Fe C
Bal. 28-
32%		 3.5-
5.5%		 1.5%
Max		 3%
Max		 2%
Max		 3%
Max		 0.90-1.40%
Max
Mechanical Properties
Ultimate Yield Elongation Hardness
(KSI) (KSI) (%) (Rockwell)
195 121 4.5 C 42 - 49
General Data
HPA Cobalt 6BH Wear Resistant
UNS R30016 Co-Cr-W
Hot Worked, Aged, Air Cooled
Density 0.303 lb/in
Specific Heat (@ 72°F) 0.101 Btu/lb/Deg F
Thermal Conductivity (32 to 212°F) 103 Btu-in./sq. ft.-hr.-°F
Electrical Resistivity (68°F) 546 Ohms/ cir mil ft
High Performance Alloys for High Performance Service
Applications
  Applications for alloy 6BH include tile making machines, rock crushing rollers and cement and steel mill equipment. Alloy 6BH is well suited for valve parts, pump plungers, shafting and sleeves.
  Food preparation machinery that cuts, chops, slices, dices and shreds uses Cobalt 6BH for its wear life, and minimal metal loses. The F.D.A. has issued approval for food contact due to its minimal metal loss, and government approval of cobalt containing equipment.
  Cobalt 6BH is also use in non-food applications such as tire cord cutting, carpet cutting, trimming knives for ceramics, leather knives, surgical blades, and Kevlar. Other applications include saw blade tips, scrapper blades, chippers, shredders and other cutting edges.
  Wrought alloy 6BH offers the fatigue resistance and toughness of a hot worked microstructure, with the heat corrosion and wear resistance of cobalt based alloy. High Performance Alloys, Inc. inventories sheet, and plate. Bar can be produced 1/2" through 2-1/2" diameter. Bar can be supplied in random lengths or cut to order. Sheet and plate offered as whole plates, or can be abrasive cut, or processed further using waterjet services.
  Other applications are steam turbine erosion shields, chain saw guide bars, high temperature bearings, valve stems, food processing equipment, needle valves, centrifuge liners, hot extrusion dies, forming dies, nozzles, extruder screws, & many other miscellaneous wear surfaces.
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-degree (0.9 rad.) negative tool holder and a 30-degree (0.52 rad.) or 45-degree (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-degree (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 may cause surface imperfections.
HPAlloys Cobalt 6BH * CoCrW * UNS R30016
Brazing
Alloy 6BH 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. Brush joining areas generously 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 6BH 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-degree (0.9 rad.) negative tool holder and a 30-degree (0.52 rad.) or 45-degree (0.79 rad.) lead angle. Tools for facing or boring are essentially the same except for when greater clearances are 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-degree (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 this may cause surface imperfections.
High Performance Alloys for High Performance Service
Wear Data
Average Abrasive Wear Data
Alloy Condition Wear Factor Hardness
HPAlloys 6B Annealed 0.072 Rc 38
L605 Annealed 0.535 Rc 24
1090 Steel 1 hr. 1600 °F, WQ,
4 min. 900 °F		 0.368 Rc 55
316 SS Annealed 0.796 Rb 86
304 SS Annealed 0.914 Rb 92
Wear factor determined by dividing material wear rate by wear rate of 1020 hot rolled steel
Average Coefficients of Static Friction for Common Materials
Material Against HPAlloy 6B Cast Iron Bronze Aluminum Lead
HPAlloys 6B 0.119 0.123 0.125 0.138 0.119
Cast Iron 0.123 0.199 0.245 0.213 0.225
Bronze 0.125 0.245 0.231 0.257 0.249
Aluminum 0.138 0.213 0.257 0.213 0.328
Lead 0.119 0.225 0.249 0.328 0.290
Coefficient represents tangent of angle of repose. Test on dry surfaces having better than 120 grit finishes. All values based on averages and are to be used comparatively and not as absolute values.