May, 1999 - Micro-Melt® Maxamet™alloy, a premium high speed steel made by powder metallurgy, is the first in a new series of PM steels from Carpenter Technology Corp., Reading, PA, designed to bridge the hardness gap between high speed steel and cemented carbide.

The new alloy offers higher wear resistance and hot hardness than current high speed steels, along with substantially greater toughness and better machinability than carbide.

According to Carpenter, its new Micro-Melt Maxamet alloy has consistently attained a room temperature hardness of HRC 70 minimum. This is distinctly above the maximum hardness achieved by conventional high speed steels, and approaches carbide hardness of HRC 75 and above, as converted from the HRA scale.

With its improved hardness, Maxamet alloy may be considered by shops that need to produce parts faster in order to stay competitive. It has been specially formulated to approximate the performance of carbide, but at lower cost.

The alloy, a product of Carpenter research and development, is a candidate for applications such as hobbing tools, form tools, broaches, shave cutters, end mills, drills and a variety of wear components that are currently made from either conventional high speed steel or cemented carbide.

In field tests, machines with Micro-Melt Maxamet alloy tooling were run at speeds higher than those possible with traditional PM high speed steels, and at speeds nearing those used with carbide tooling.

Maxamet alloy is considered by Carpenter as a candidate material for dry machining (as compared with the use of cutting fluids) applications because of its resistance to the higher temperatures generated by this increasingly popular metalworking practice. At a temperature of 538°C (1,000°F), the new PM grade has a hardness of HRC 60.

This higher hardness tooling material is also considered advantageous to back up the high-hardness PVD and CVD coatings commonly used to extend the service life of premium cutting tools. Some of these coatings exceed a hardness of HRC 70.

Micro-Melt Maxamet alloy is designed to offset the drawbacks found with carbide tooling. First, the initial carbide blanks used to make the tooling are expensive, and so is the fabrication of tooling from those blanks. Second, carbide tooling has very low toughness; therefore, extreme care must be taken to prevent fracture during service. Third, a large percentage of existing machines are not rigid enough to run carbide tooling.

Typical analysis of Micro-Melt Maxamet alloy is: carbon 2.15%, chromium 5.0%, cobalt 9.0%, tungsten 13.0%, vanadium 6.0%, balance iron.

For a technical data sheet or sample material, call Robert E. Carnes at (610) 208-2579.