Imperfections Left On Blade After Quenching

W

wiggles18

Joined
Oct 15, 2010
Messages
6
I am new to blade smithing and half a question.

Why, after quenching, do my blades have these strange random pits left on them? The pits only appear on the area of the blades that have touched the water and brine. I'll list all the information of how I went about making the blade(s).

Forged a tomahawk out of a medium carbon railroad spike, heated it slightly above non-magnetic(didn't let it sit for a set amount of time at the color, just heated it and took it out) and let it cool down. Then I cleaned and profiled the hawk by file and then hand sanded it to 400 grit. Then I heated it above non-magnetic again, let it cool, put it back in the forge till it was bright cherry red, edge quenched it in brine. Then I hand sanded the scale off, saw the pits, tried to sand them out, but they wouldn't come out. All of the heating was done with a coke forge.

This has happened to all of my blades so far that I have made. I've tried a bunch of different things, torch for heat treating, brine quench, water quench, sanding to 400 before heat treating, sanding to 800 before treating, 1500 etc( I like a mirror to near mirror finish), but nothing made a difference.

Does it matter what water you use to quench in; can it be tap water? Etc.

I really need help with this and I appreciate any information anyone can give.
 
When you say ,"Bright Cherry Red", do you mean you took the blade much hotter than non-magnetic? If so you may have grown huge grains that are being pulled out in the finishing, and leaving behind the pits.

Another possibility is that the pits are also in the softer steel, too, but they are burnished over and closed up in the finishing.

Also, since the hawk was forged from a RR spike there was a lot of metal being moved about. The edge area is where the movement and stretching was the most. Any scale or cinders formed in the fire, or left on the anvil face, will be hammered into the blade.....and with much more hammering done on the edge area, more inclusions could be hammered into those areas. This often isn't obvious before HT,but it gets exposed in more detail by the hardening process.

Final question/observation - how much material are you removing from the surface to try and get rid of the pits? A certain amount will need to come off after HT to expose the hardened steel.
 
Someone told me to get it to the point where it is just about to change to orange, is this wrong? I would say I get it to the point of orange-red. Please correct me as to what temperature or color I should get it to before quenching, preferably by edge quenching the items and letting the heat from the spine/ cheek of the hawk draw out to temper.

I have also got these pits(much more actually) on a blade after heat treatment that I did stock removal on(can these inclusions be put into the blade using a hand file for stock removal?).

I try to just remove the scale after HT by sanding with the same grit I did before, sometimes I go a few grits back to speed up things, then progress back up. With the pits I tried sanding with 80 grit by hand for an extensive amount of time, I even tried using an orbital grinder( don't really have a selection of power tools to work with, which is why I mainly stick to working entirely by hand) and I couldn't get the pits out.

I didn't know I was supposed to try and remove any of the steel after HT; I thought the scale was the target. How much should I take off, and how should I go about taking it off using only the tools I have at hand: files, sandpaper?

Thanks.
 
Sounds like you are giving it a good go, but using old myths rather than proven methods.

Temp by color? In what light. It will change with the light in the room or where ever your are heating the steel.

Partial quench?Another old but bad method. If only using a partial quench, you are never changing all of the steel from a coarse to fine grain structure. It can cause bending, or worse, a crack at the wrong time.

Rather than spend an hour touting would suggest a few books.

The 50 dollar knife shop by Wayne Goddard. How to make Knives by Loveless And Barney. Or study heat treating. Use your computer! There are many sources out there.

Hint= finishing is done after heat treating. That is why they call it finishing. If it was done before, it would be called beginning!

Just saying.

When you get finished heat treating, your work if just starting.
Also you didn't mention tempering. The quenching isn't the end of the heat treat process, but once again, the beginning.

Mike
Maker
The Loveless Connection Knives
 
With little experience and no controlled oven, a smith has to use something that tells him the steel temperature in HT. The eye is about the least accurate thing he can use. Even experienced makers are usually off quite a bit when judging by color. What looks red-orange in daylight could be 1800F or more.

Get a cheap extension magnet from HF.They cost around $1. While heating the blade, regularly remove it and check with the magnet. When the steel reaches the Currie Point ,at around 1400F, the magnet will stop sticking. This is the point we call non-magnetic. Observe the color and heat up just a tad redder. You want the steel about 100F hotter than non-magnetic.

Read the stickys at the top of this forum. There is a good one by Kevin Cashen on "working with three steels", and another on "The Process of Quenching". It has a lot of info about HT.

Filling out your profile would help,too.
 
Last edited:
Have you seen this ?

The Standard Reply to Newbies v8

The answer to a 13 year old student is different than to a 40 year old engineer, and you may have a helpful neighbour.
We can often recommend a local supplier, but that depends on where you are.
Fill out your profile with your location (Country and State at least), age, education, employment.

Look at the stickies at the top, many are expired, but not all.

The basic process in the simplest terms

Absolute Cheapskate Way to Start Making Knives-Printable PDF
Absolute Cheapskate Way to Start Making Knives-Website

This is a very detailed set of instructions by Stacy E.Apelt.
http://www.bladeforums.com/forums/showthread.php?t=694673


Books

A list of books and videos on the KnifeDogs Forum
http://www.knifedogs.com/showthread.php?t=5285

BladeForums - E-books or book previews Google books
http://www.bladeforums.com/forums/showthread.php?t=603203

I like:
David Boye-Step by Step Knifemaking
Tim McCreight-Custom Knifemaking: 10 Projects from a Master Craftsman
These are clear, well organized, widely available and inexpensive too.

Knife Design:
On the Google books thread, you can find
Lloyd Harding drawings
and
the Loveless book with large variety of proven classic styles.

Forging Books:
Lorelei Sims-The Backyard Blacksmith
A modern book with great photos for forging in general - no knifemaking.

Jim Hrisoulas- has 3 books on forging knives. Check for the cheaper paperback editions.
The Complete Bladesmith: Forging Your Way To Perfection
The Pattern-Welded Blade: Artistry in Iron
The Master Bladesmith: Advanced Studies in Steel


The $50 knife shop
It is popular, but it confused me for a long time.
Forging is NOT necessary, you can just file and grind everything away to create a knife (stock removal)

The goop quench is total Bull, commercially made quench oils are cheap and easily available, even grocery store canola oil works much better.

Junkyard steels require the skills of an experienced smith to identify the steel and heat treat it properly.
You can buy proper steel like 1084 very cheaply.
(Mentioned in the new edition)

I like cable damascus, but that is an advanced project for an experienced smith and has no place in a beginners book.

The home built grinders are the best thing about the book, but there is now a huge amount of info on home built 2x72 belt grinders on the web.
The revised edition of this book should have included this.


Videos

Heat Treating Basics Video-downloadable
http://www.archive.org/download/gov.ntis.ava08799vnb1/ava08799vnb1_512kb.mp4

Many specific how to knifemaking videos are available.
Some are better than others, but all better than nothing.

The best overall Knifemaking video I have seen is
“Steve Johnson-Making a Sub-Hilt Fighter”

The best video on leather sheath making I have seen is
“Custom Knife Sheaths -Chuck Burrows - Wild Rose”

You can see a list of some older videos and their reviews at this rental company.
They are not the quickest on getting new titles, but some videos are worth buying, some are worth renting…
Rental wait times are measured in months, buying is MUCH faster, but more costly.
http://smartflix.com/store/category/9/Knifemaking

Green Pete's Free Video
Making a Mora bushcraft knife, -stock removal, hand tools, and neo tribal / unplugged heat treat.
"Green Pete" posted it free for those who can use torrent files.

http://thepiratebay.org/torrent/4995247/Greenpete_s__Knifemaking_Basics_-_Make_a_Mora_Bushcraft_Knife
You can also find it on YouTube broken into 4 parts.


Steel
The “welding steel” at Home Depot/Lowes… is useless for knives.
If you want to ship out for heat treating, you can use ATS34, 440C, plus many others.

If you want to heat treat yourself, find some 1070, 1080, 1084,
1084 FG sold by Aldo Bruno is formulated just for knifemaking.

You can find lists of suppliers here
http://www.bladeforums.com/forums/showthread.php?t=699736

Aldo’s website inventory is unreliable, call instead.
http://njsteelbaron.com/


Heat Treating
You do not have to buy a lot of equipment to start with.
You can send out for heat treating, 10 or 15 $ per blade

This is a PDF brochure which gives good general info
http://www.buckknives.com/resources/pdf/Paul_Bos_Brochure.pdf

http://www.petersheattreat.com/
http://www.texasknife.com/vcom/about_us.php
http://www.knifemaker.ca/ (Canadian)
and others


Grinder / Tools

Hand Tools
You can do it all by hand with files and abrasive paper.
The Green Pete video does it this way.

Photo of a nice bevel filing jig .
http://www.flemingknives.com/imagesPrime/FileStation/KPicB007.jpg

Entry Level Grinders
Many makers start with the Sears Craftsman 2x42 belt grinder.


Commercial Production 2 x 72” Belt Grinders
http://www.prometheanknives.com/shop-techniques-3/grinders

Mapp arm
http://www.bladeforums.com/forums/showthread.php?t=466024


DIY 2 x 72” Belt Grinders

KMG Clone
Free Plans
http://www.dfoggknives.com/PDF/GrinderPlans.pdf

NWG No Weld Grinder
http://www.usaknifemaker.com/plans-for-the-no-weld-grinder-sander-nearly-50-pages-p-723.html

EERF Grinder (EERF =“Free” backwards)
Free plans
http://wilmontgrinders.com/EERFGrinder.aspx
http://blindhogg.com/blueprints.html

Buy the kit
http://polarbearforge.com/grinder_kit.html
 
Thanks for the help. I'll do the magnet thing at the moment, then head over to the library to pick up some books.
 
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