Jump to content
I Forge Iron

stainless steel fire scale


Recommended Posts

Hello guys,

wasn't there for a very looong time (years!, sorry for that) but if one has a blacksmithing related question this forum is the way to go!

I'm doing a lot of work in stainless at the moment because my customers like the 'bare' steel finish without rust. So the fire scale it develops during forging is a necessary feature in my work as it looks as "normal" mild steel.

What I don't really understand is how and when the scale develops (and if not, why!!). After doing welds (sometimes) or after working with the grinder I often have the problem to get the scale back on the ground spots which looks really ugly (I have really problems to explain it as English is not my mother tongue, but if you work with SS you should know what I'm talking about)

 

Greetings from South Africa

Frank

Link to comment
Share on other sites

Thanks for the answers guys.

Sometimes there is no other possibility than using the grinder even if I try to avoid it. Ok, in any case you can start from scratch and make a completely new part :rolleyes:, but that's not really economical...

I realized there are many factors which affects the development of fire scale. surface texture, smoothness and - of course - time. The funny thing is whenever I put the part under the (power) hammer the scale develops much easier even if the part is not that hot and was in the forge for a short time only... something I don't have an explanation for and that was the reason for my confusion...

hinge2.thumb.jpg.608fb054a2b26af669571ea0bea8e3af.jpg

hinge1.jpg

Link to comment
Share on other sites

First a disclaimer, I have limited experience and my comments may need correcting by those who know more. My understanding is that nickle passivates easily and forms an oxide layer which contributes to its stainless nature. When you work with the power hammer you are working hot and drawing out and so breaking the surface layer which exposes the fresh hot surface to oxygen. When grinding, you are working cold. The passivated layer can reform and interfere with regaining the finish you are looking for. I hope those who are more knowledgeable will either validate or refute this. 

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...