heat treat stainless steel

My name is Bruno, I live in Italy. I've recently discovered this forum and I find it very intresting for a beginner like me and now I've a question to ask. I've recently purchased an electrico oven (it reach 1100 ?C) to heat treat my blade; I use stainless steel named MA5M (is similar to the AISI 440 A) and I would like to have some information about how to heat treat stainless steel, for example I would like to know if is possible put the blade in the oven without problem (someone told me that the blade must be wrapped in a steel foil to prevent loss of hardness on the surface of the blade) and in this case is better to begin to grind a little bit the blade before heat treat and continue to grind after heat treat?
I'm sorry for my English, I hope you understand what I mean and I hope that someone will help me.
Best regards, Bruno.

Bruno,

Welcome to our forum! Don't worry about your English, it's fine.

It is necessary to protect the blade when hardening stainless. If you don't, a lot of very hard scale will form and you will lose a lot of carbon from the surface of the steel. There will usually be excessive pitting as well.. So, for a many reasons, the blade must be wrapped in Inconel foil or the oven must be filled with Argon gas, or the blade can be painted with a high temperature air tight compund. The idea is to keep oxygen away from the blade at these extremely high temperatures. Even with this protection you will probably get better results if you do not finish grinding until after the heat treat....

Thank you Ray for you answer.
I think that the best way for me is to wrap the blade because, I think that is not possible fill my oven with Argon (probably the oven must be made for work with Argon inside). In wich way I must quench the blade wrapped to prevent that the blade twist?
Taking advantage of your availability can you explain me something more about the third method you have written above (paint the blade with a high temperature air tight compund)? Wich kind of compound I must use?

Thank you again
Bruno

Most any oven can be fitted for an argon tap. All they really do is drill a small hole through the back of the oven, all the way through the fire brick. Then they attach what ever fittings they need to the outside wall so that when the gas is released it just feeds through the hole and into the oven. It can be more sophisticated that this but that's the minimum system.

When you are using the foil and it is time to quench the blade, the foil must be removed. I think most people use a pair of shears or tin snips to quickly cut the foil off.

I don't remember the name of the compound for coating the blades. It was Neil Charity that told me about it (he uses it) and you can find him in the Folder Forum.

Good luck...