Austenitic Stainless Steel
Expanite surface hardening can be applied to a variety of alloy materials and all main categories of stainless steel including austenitic.
UNS S30400 / S30403 / AISI 304 / 1.4301 / 1.4307
UNS S31600 / S31603 / AISI 316 / 316L / 1.4404 / 1.4435
UNS S30300 / AISI 303 / 1.4305
Properties of Austenitic stainless steels
Heat-resistant grades are designed for applications at elevated temperatures, typically exceeding 600°C (1,100°F).
The purpose of the process
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.