Unique Wear Reduction by Using ExpaniteHigh-T Hardening on Martensitic Stainless Steel!

Martensitic Wear Test G133.

Wear is a pervasive problem for stainless steel, - also on martensitic stainless steels and even after vacuum hardening. Based on a standard ASTM G133 test for wear resistance of materials, the reduction in wear for martensitic stainless steel with the ExpaniteHigh-T surface hardening process is truly remarkable and shows that Expanite® is the leading solution to drastically improve the lifetime of your parts and products!

Ball-on-flat Sliding Wear Test (ASTM G133).

The ASTM G133 test geometry involves a pin with a ball shaped tip, sliding in a reciprocating motion with a constant force of 25N, doing 5400 strokes with an amplitude of 10 mm. After the test has been completed, the resulting wear track is both visually inspected and measured with a profilometer. From this data, values for the depth and volume of the wear track can be gathered. In this case, two solutions with martensitic stainless steel were tested, one with standard vacuum hardening and one with ExpaniteHigh-T hardening.

Data and graphs wear                           Data and graphs wear


Improve your parts with ExpaniteHigh-T.

Expanite’s solution heat treatment process for martensitic stainless steels such as EN 1.4021 or American standard AISI 420A used in this study, consists of three distinct steps. First is high temperature solution nitriding of around 1mm depth, providing increased surface hardness (even 100 HV above core) and improved pitting resistance, owing to up to 1.0 wt% of diffused nitrogen. Second step is a sub-zero deep cooling treatment, ensuring homogenous martensitic structure throughout the part. Lastly, low temperature tempering is conducted to improve core toughness. Such treatment provides excellent results in trials conducted under laboratory
conditions such as ASTM G133 test, and can be readily applied to martensitic stainless steel parts to vastly improve their livetime.

ASTM G133 Wear

Over 300 Times Lower Wear Rate.

Cross-sections of wear tracks can be seen in profiles shown on the graph in Figure 1. The results obtained from testing ExpaniteHigh-T treatment applied on martensitic 1.4021 alloy show approximately 320 times shallower wear mark, as compared to a standard vacuum hardening. This in turn means that the overall wear rate was reduced over 300 times (see Table 1)! The photos in Figure 2 further demonstrate the superior wear properties of the ExpaniteHigh-T treatment on a 1.4021 alloy. The visible markings on the left-hand side image, showing the ExpaniteHigh-T treated surface, is only partially prescribed to an actual wear. The visible track is predominantly a polishing of the surface. The right-hand side photo shows vacuum hardened test samples, and demonstrates severe wear, both on the plate and the counterpart.


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