Blake D

New to metal, having issues with Heating

Recommended Posts

HI, I am completely new to working with metal but am a pretty experienced woodworker. That being said im not an idiot but im also not sure on what I am doing most of the time. My biggest issue is when i make a knife, with material removal not forging, I heat the steel to a non magnetic state, pull it out and brush it and then put back in for a few mins and then pull out to normalize. I do this 3 times and on the final stage I dip in warm canola oil. When I pull it out of the oil I noticed large black spots everywhere and when I take it to the grinder I realized that the divots went so deep into the steel that the knife was ruined. It looked like it had rusted for 30 years and had extreme pitting. I have searched and searched and can not find anything on this issue. Im not sure if im using the proper terminology which could be the reason I cant find what I need. If this is the wrong spot to post please let me know and I will move. This is the first time on this forum, thanks for any help, tips, advice.

Share this post


Link to post
Share on other sites

What alloy are you using and how are you heating it.

Also how thick is it at the edge when you quench it?

Mechanick Exercises; published in 1703 mentions "He that will a good edge win,  Must forge thick and grind thin."

It is possible that you are not leaving enough meat to remove the hardening oxidation.  A picture would help.

Also it really helps to go through it with someone who knows the ropes. Not knowing even what country of the 100+ that participate here I can't make a suggestion where to find such a smith.

Share this post


Link to post
Share on other sites

Sounds like scale to me as well.  During your normalization cycles (which, btw, should be one in the full austentizing range, one just barely above non-magnetic and one at a dull red with cooling down to fully magnetic in between each cycle), don't keep it at elevated temperatures any more than necessary, and try to keep in a reducing atmosphere to reduce scale.  Also, when you go to harden (with the quench) you need to heat to full austentizing, like the first normalizing pass, and get into the heated canola as quickly as possible.  Then clean off the oil and temper the steel.  

I find it isn't worth going past around 120 grit before heat treatment as some scaling is pretty inevitable (unless you use an anti-scale coating, wrap in stainless foil, heat in an electric heat treatment oven with an inert gas purge, or go with salt baths, but none of these sounds practical with your current smithing status or experience).  What are you using to heat treat and what for grinding?

Share this post


Link to post
Share on other sites

Welcome to IFI! If you haven't yet, please READ THIS FIRST!!!

And especial greetings as one woodworker (former, in my case) to another!

Share this post


Link to post
Share on other sites

I read that JHCC thanks for the link, I will post pictures as soon as I am able. I was always under the impression that the scale was removed with the brush. It’s 1080 1/8” steel and I most definitely over heated it based on the above reply’s. I will try it one that and just move to a 1/4” 1080-1095 maybe. I know now that this was way to hot and I do know that the fire is way to large but I can’t really do much else with a shop vac, I am running a store bought charcoal mixed with charcoal I made out of some maple and cherry scraps I had laying around

Share this post


Link to post
Share on other sites

Is your store bought charcoal briquettes or lump charcoal? There are a lot of ways to use less air from a shop vac, most of them dead simple: example: have the tue pipe and vac hose non-concentric.  Put in 1 or more Tees with open branches.  If your forge has an ash dump prop it open....

Share this post


Link to post
Share on other sites

Store bought can be lump; or it can be briquettes. Stores sell both; at least most places I have checked here in the USA. (Like Wally World)

I assume you are trying to say store bought briquettes, which can cause problems as they have more trouble getting a reducing atmosphere especially with too much air flow.

So have you tried running it with the ash dump open to reduce air into the forge?

Share this post


Link to post
Share on other sites

Thomas I’m sorry I did mean briquettes by store bought. I have not tried that, my biggest issue was the pitting which I’ve gathered is just an excess of scale, it’s crazy to me that it could be that much but that seems the most probable cause. I have only run the forge once last night and will try again this weekend with all lump, ash dumb open and probably put a ball valve on the end of the shop vac to reduce the air flow. I really wanted coal, I just can’t get past the idea but it’s impossible to find from the area of Kentucky we visit on down here to Mississippi and I’m not paying online prices. It gets plenty hot though, I was able to play around with some crappy rebar I had laying around and flatten it out nicely. 

Share this post


Link to post
Share on other sites

Hot and extremely oxidizing can go hand in hand and destroy your work.. Give you a hint: Rehder in "The Mastery and Uses of Fire in Antiquity" states that the reducing area of a bloomery starts around 13 TIMES the mean size of the fuel used.  A forge differs from a smelter; but think of heaping the fire more than 13 briquettes high!   Ask a cook if hotter is always better.

What did the local ABANA Affiliate suggest when you asked them where to get coal?  I used to be a member of SOFA and bought all my coal from them; great coal reasonable rates as they would buy it by the train car load and parcel it out.

Share this post


Link to post
Share on other sites

Thomas I hadn’t heard of the ABANA before but I didn’t do a quick check and pulled up their page. I’m not seeing much for Mississippi but I will give em a shout and see what they say. Thanks 

Share this post


Link to post
Share on other sites

Your fire is not large enough or deep enough in my opinion.  Make a 4-6 inch tall piece of light metal 22 ga to 11 ga and add it to the top of the forge in the shape of a (  ). This will add depth to the fire and allow you to pass metal through and across the fire. You want a fire ball about the size of a melon or larger, with more fuel on top of that being coked up. The metal should go in about 1/2 to 2/3 of the way up the fireball.

Fuel does not make the fire hot, air makes the fire hot. Use only the amount of air you need to get the heat you want.

image.png

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now