Chemistry

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 Haynes’ Nominal Mechanical/Tensile Properties of Alloy 25 (L-605) Rod & Bars. For most common forms and exceptions, check out the datasheet linked underneath the table.

UTS = Ultimate Tensile Strength, YS = Yield Strength, OS = Offset, HR = Hot Rolled

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.

Physical Properties

Cold Red. = Cold Reduced

Metal-to-Metal Galling Resistance

Cobalt Alloy L605 exhibits excellent resistance to metal galling. Wear results shown below were generated for standard matching material room-temperature pin on disc tests. Wear depths are given as a function of applied load. The results indicate that alloy L605 is superior in galling resistance to many materials, and is surpassed only by Ultimet® alloy and Stellite® alloy 6B. Both of these materials were specifically designed to have excellent wear resistance.

High Temperature Hardness Properties

The following are results from standard vacuum furnace hot hardness tests. Values are given in originally measured DPC (Vickers) units and conversions to Rockwell C/B scale in parentheses.

Aqueous Corrosion Resistance

Haynes 25 (L605) was not designed for resistance to corrosive aqueous media. Representative average corrosion data are given for comparison. For applications requiring corrosion resistance in aqueous environments, Ultimet alloy and Hastelloy’s corrosion-resistant alloys should be considered.

Oxidation Resistance

Cobalt alloy L605 exhibits good resistance to both air and combustion gas oxidizing environments and can be used for long-term continuous exposure at temperatures up to 1800°F (980°C). For exposures of short duration, alloy L605 can be used at higher temperatures.

Oxidation Test Parameters

Burner rig oxidation tests were conducted by exposing samples 3/8 in. x 2.5 in. x thickness (9 mm x 64 mm x thickness), in a rotating holder, to products of combustion of No. 2 fuel oil burned at a ratio of air to fuel of about 50:1. (Gas velocity was about 0.3 mach). Samples were automatically removed from the gas stream every 30 minutes and fan-cooled to near ambient temperature and then reinserted into the flame tunnel.

Thermal Stability

When exposed for prolonged periods at intermediate temperatures, Cobalt alloy L605 exhibits a loss of room temperature ductility in much the same fashion as some other solid-solution-strengthened superalloys, such as Hastelloy® alloy X OR Inconel® ALLOY 625. This behavior occurs as a consequence of the precipitation of deleterious phases. In the case of alloy L605, the phase in question is CO₂ W laves phase. Haynes® alloy 188 is significantly better in this regard than alloy L605.

Machining

The alloys described here work harden rapidly during machining and require more power to cut than do the plain carbon steels. The metal is ‘gummy,’ with chips that tend to be stringy and tough. Machine tools should be rigid and used to no more than 75% of their rated capacity. Both work piece and tool should be held rigidly; tool overhang should be minimized. Rigidity is particularly important when machining titanium, as titanium has a much lower modulus of elasticity than either steel or nickel alloys. Slender work pieces of titanium tend to deflect under tool pressures causing chatter, tool rubbing, and tolerance problems. Make sure that tools are always sharp. Change to sharpened tools at regular intervals rather than out of necessity. Titanium chips in particular tend to gall and weld to the tool cutting edges, speeding up tool wear and failure. Remember- cutting edges, particularly throw-away inserts, are expendable. Don’t trade dollars in machine time for pennies in tool cost.

Feed rate should be high enough to ensure that the tool cutting edge is getting under the previous cut thus avoiding work-hardened zones. Slow speeds are generally required with heavy cuts. Sulfur chlorinated petroleum oil lubricants are suggested for all alloys but titanium. Such lubricants may be thinned with paraffin oil for finish cuts at higher speeds. The tool should not ride on the work piece as this will work harden the material and result in early tool dulling or breakage. Use an air jet directed on the tool when dry cutting to significantly increase tool life.

Lubricants or cutting fluids for titanium should be carefully selected. Do not use fluids containing chlorine or other halogens (fluorine, bromine or iodine), in order to avoid risk of corrosion problems. The following speeds are for single point turning operations using high speed steel tools. This information is provided as a guide to relative machinability, higher speeds are used with carbide tooling.