Also named martensitic or quench hardening, neutral hardening is a heat treatment used to achieve high hardness/strength on steel. It consists of austenitising, quenching and tempering, in order to retain a tempered martensite or bainite structure.
There are several benefits of neutral hardening, depending on the steel type:
Heavy loaded parts can be given an optimal combination of high strength, toughness and, if applicable, temperature resistance
Such parts can be made lighter and more stiff, due to higher strength
Tools and dies get the required high wear and/or heat resistance while maintaining toughness
Parts that need grinding to low roughness, acquire the required machinability
For all these purposes, if the parts are made of martensitic stainless steels, the corrosion resistance is only available after the heat treatment
Tool steels: the desired properties of high hardness, wear resistance, heat resistance and machinability can only be given by hardening.
Martensitic stainless steels: these steels only get their maximum corrosion resistance by hardening.
For all steel types: during the shaping of the parts, (takes place before the heat treatment), the material is relatively soft and therefore easy to machine.
Application & materials
Highly loaded parts, such as drive shafts, carrier bars, frames, fork lift forks, nuts and bolts, lifting eyes etc.
Similar parts, intended for elevated temperatures
Springs of any kind, and any dimension
Tools: cutting, hammering, rolling i.e. any kind of tooling for cold, as well as for hot working