The welding rods and powders covered by this specification are intended for applications for resisting wear and impact, covering a range of conditions where corrosion, erosion, and abrasion are considered factors in choosing the proper rod or powder. The interchangeable use of basic types should not be done without the approval of the command or agency concerned.

Rod types MIL-RCoCr-A-1 and -2 are intended for deposition by the oxyacetylene process. Carbon pickup from the oxyacetylene flame, which is characteristic of this process, is usually necessary to obtain desirable hardness levels in the hardsurfaced deposit.

Rod type MIL-RCoCr-A-3 is intended for deposition by the tungsten-inert gas (TIG) process and contains sufficient carbon to attain desirable hardness levels in the hardsurfaced deposit. Deposition by the oxyacetylene process will increase the carbon content and hardness of the deposit and may result in excessively hard and brittle deposits. Therefore, this type of rod should not be used with the oxyacetylene process.

This alloy is more resistant to abrasion than type MIL-RCoCr-A and will attain a minimum hardness of 50 Rockwell C. It is more brittle, of higher strength, and considerably less resistant to thermal shock.

This alloy is similar to types MIL-RFeCrCo, MIL-RNiCr-C, and MIL-RNiCr-D in respect to hardness and resistance to certain types of abrasion.

This alloy is similar to type MIL-RCoCr-C in respect to hardness and resistance to certain types of abrasion and intended for use with tank sprockets.

This alloy is similar to types MIL-RFeCrCo, MIL-RNiCr-B, and MIL-RNiCr-C in respect to hardness and resistance to certain types of abrasion.

This alloy is intended for use with tank treads, pins, and bearings.

This alloy is similar in hardness and resistance to certain types of abrasion, to type MIL-RCoCr-A. For some purposes it is an alternate and may be used interchangeably.

This alloy may be expected to attain a minimum hardness of 43 Rockwell C. It has intermediate properties between type MIL-RCoCr-A and MIL-RCoCr-C.

This alloy is more resistant to abrasion than MIL-PCoCr-E-1. It is somewhat less resistant to thermal shock.

For purposes of specifying a process to make the useability test, rods are commonly deposited by oxyacetylene gas welding or by inert gas tungsten arc welding while it is recommended that powders be deposited by the plasma transferred arc process.