Thermallife Benefit - More wear resistance

Increases Wear Resistance

ThermaLLife is a chemical diffusion process whereby the tool steel is heated to a subcritical temperature and gases are introduced into the environment. The gases have both a carbon and nitrogen element.

With added atmospheric pressure, the Nitrogen and Carbon gas atoms are diffused into the surface of the tooling. With this a small sustained value of beneficial compressive stress is added along with a compound and diffused zone.

The diffusion layer for die casting dies is about .004”-.006” in depth with a compound layer of .0003” to .0005”. The compound layer is the function aspect of the process that prevents soldering in most die casting applications. This layer forms a barrier between the aluminum and iron that prevents the covalent electron bonding of the two elements, leading to a soldered condition. The increased fatigue strength comes from the created compression curve. The nitrogen and carbon atoms, that are diffused into the steel, stretch the surface and create the opposing layer of compression.

The hardness is measured in Vickers (1200-1500) since normal Rockwell readings penetrate through the thin diffusion zone. This Vickers reading, if approximated to HRc would be about 65-75. The compound layer hardness is usually in the range of 1000 Knoop (10g). The photo at the right shows diamond marks. These are micro hardness readings of the diffusion zone. The smaller the diamonds, the harder the material.

This combined hardness makes the FNC material more resistant to wear, erosion, and scuffing. Both the diffusion and compound layer are effective combinations to ward off corrosion, oxidation, and soldering.