Uddeholm Elmax® Superclean Stainless Steel

Description

HEAT TREATMENT of Uddeholm Elmax:

SOFT ANNEALING:
Protect the steel and heat through to 980°C, holding time 2h. Then cool in furnace 20°C/h to 850°C. Holding
time 10h. Cool slowly to 750°C. Then freely in air.

STRESS-RELIEVING:
The steel should be heated through to 650°C, holding time 2 hours. Cool slowly to 500°C, then freely in air.

HARDENING:
Preheating temperature: 600–850°C.
Austenitising temperature: 1050–1100°C, normally 1080°C.
Protect the part against decarburization and oxidation during hardening by using heat treatment foil.

TEMPERING:
Choose the tempering temperature according to the hardness required by reference to the tempering graph. Temper twice with intermediate cooling to room temperature, the preferred tempering temperature is 180°C – 220°C.
Holding time at tempering temperature minimum 2 hours.

QUENCHING MEDIA:
Forced air/plate quench between 2 thick aluminium plates. Or, Quench in PQ20 Medium Quench Oil.
Note: In order to obtain optimum properties, the cooling rate should be as fast as is concomitant with acceptable distortion.

SUB-ZERO TREATMENT: (if preferred)
Sub-zero treatment falls into the broad categories of cold treatment and cryogenic treatment.
Parts requiring high dimensional stability should be sub-zero treated, otherwise volume changes may arise.
Uddeholm Elmax SuperClean is commonly sub-zero treated between -150°C and -196°C (cryo treatment), although occasionally -40°C to -80°C.

The first sub-zero treatment should be carried out directly after hardening and before any tempering without delay. When maximum dimensional stability is required further sub-zero treatments may be necessary between the tempering operations. In this case it is important to always end with a tempering, as the last operation. 1–3 hours treatment results in an increased hardness of about 1–3 HRC.
Note: Avoid intricate shapes as there is a risk of cracking.

For further reading: https://www.uddeholm.com/app/uploads/sites/10/2023/08/productdb/api/tech_uddeholm-elmax_en.pdf

DISCLAIMER:

All info above is from my readings of research papers, forum posts, and discussions with people. I am not a metallurgist and the above is presented here for the benefit of all knifemakers. You do not have to follow them and I’ll not be held responsible for any loss or damage you may experience.