Martensitic Stainless Steel
Expanite surface hardening can be applied to a variety of alloy materials and all main categories of stainless steel including martensitic
UNS S42010 / AISI 420 / 1.4021
UNS S44002 / AISI 440A / 1.4040
Properties of Martensitic stainless steels:
Martensitic can be hardened through heat treatment, typically achieved by either quenching and stress relieving or quenching and tempering processes. The specific composition of the alloy, combined with the rapid cooling during quenching, facilitates the formation of martensite. Un-tempered martensite, however, tends to be low in toughness and consequently brittle. On the other hand, tempered martensite provides steel with a desirable balance of hardness and toughness, which is particularly advantageous in applications such as medical tools (including scalpels, razors, and internal clamps).
The purpose of this process is to dissolve nitrogen in the surface of stainless steel to a depth in the range of 0.2-2 mm. Peak hardness ranges from 280HV on austenitic grades to 950HV on martensitic/ferritic grades.
The purpose of this process is to dissolve nitrogen and carbon in the surface of stainless steel to a depth in the range of 5 - 30µm. Peak hardness ranges from 1100-1300HV.
The purpose of this process is to combine ExpaniteHigh-T and ExpaniteLow-T processes to achieve higher load bearing and corrosion properties. Firstly, the ExpaniteHigh-T process is applied to create a deep case depth with moderate nitrogen content. Secondly, the ExpaniteLow-T process is applied to create a high-hardness surface on top of the ExpaniteHigh-T zone. The Expanite process does not result in a coating, but a diffusion zone with an increased carbon and nitrogen content. We call this zone expanded austenite, expanded martensite or simply: Expanite.