Yes – EN42 grades are generally considered nitriding steels. That is probably why the searches state 'consult your HT specialist' as there are several techniques for nitriding and not all HT specialists can handle these processes. For instance, there is the oldest but rarer nowadays treatment which employs ammonia atmosphere system where the component is placed in an ammonia atmosphere at around 800C for between 24 and 36 hours to absorb the Nitrogen, there is a process which uses a Carbon/Nitrogen rich soak, and various other variants such as TCN. Due to the energy costs this is not a cheap process or a home workshop capability. It will probably carbon harden or oil quench but not as favourable as other steel grades.

The steel is used in crankshafts and gears where extreme hardness is required – nitriding will impart a surface hardness of typically 900 VHN yet allow a core toughness which gives components immense fatigue resistance.

Edited with additional points and spelling mistkaes!

Edited By Oily Rag on 25/06/2020 08:49:34

Edited By Oily Rag on 25/06/2020 08:51:29

Robin, I have no experience of EN42 but use EN45 & 47 regularly for springs and the carbon content in EN42 is sufficient for “normal” hardening, I would suggest heat to 850 C and quench in oil then temper to desired hardness, for knives I would suggest 280 C but you may have to experiment. This would be far too hard for a spring ! You need to temper to 340/350 C for Springs

Look at **LINK** for some info

There a couple of knife makers close to me, one uses files to produce unique products the other uses tool steel, aka gauge plate. Lots of info on the web if you dig around

John

Edit spelling & typo errors 

Edited By JohnF on 25/06/2020 10:03:55

I guess it depends on the type of knife and what you want it to do and look like.

I make blades and back springs from 01 tool steel, it polishes up beautifully but obviously rust is a problem if you want to use the knife wet. I have bead blasted some blades and got a slightly more resilient finish for a work knife.

Hardening has always seemed a dark art for anything more exotic than tool steel and beyond my home made knife skills.

I believe that most of our Bowie blades were made of EN 42 and were hardened by a specialist heat treatment firm in Sheffield. Again not stainless but just as good looking as long as they are cared for properly.

Mick

Robin I have sent you a message on this site at top of page.

David