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

AISI 420 is martensitic stainless steel specially designed for applications requiring high mechanical properties combined with improved corrosion resistance relative to traditional martensitic steels. Ideal for applications requiring high strength, high hardness, and corrosion resistance similar to AISI 304/ 1.4301 stainless.

UNS S44002 / AISI 440A / 1.4040

AISI 440A is a high-carbon high-chromium martensitic stainless steel designed to provide stainless properties with excellent hardness. The alloy has an excellent combination of strength, ductility, toughness, corrosion resistance, and workability. It attains a hardness of 56 HRC and maximum toughness when heat treated and has good toughness at cryogenic temperatures and relatively high tensile and yield strengths at moderately high elevated temperatures. These properties further increase.

 

The purpose of the process:

ExpaniteHigh-T

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.

ExpaniteLow-T

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. 

SuperExpanite

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.

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