Cracking

[Vandle]

I've made a few nice blades from O1 steel, but this week thought I'd make some from recycled metal.  First off an old file that went well until I noticed a crack in the tang.  I heated it again and the tang just fell off.  After I cooled the blade and cleaned it up, realised (sorry - UK spelling) a massive crack across the tip was also a problem.  Started afresh with a length of coil spring and the same thing happened - small cracks appearing as the blade edge was being formed.  Tried a third time to make a letter opener from a small file, and the same thing again.

So, I understand the coil spring could have deformities in it already, but three on the trot makes me thing I'm forging incorrectly.

Any thoughts?

[ThomasPowers]

looks overheated to me.

[Vandle]

Really?  I've tried forge welding and can't get it hot enough - thought I'd need a second burner.  It's usually very bright red.

I'll try lower temperatures. Thanks.

 

[Jclonts82]

it LOOKS overheated, but that pitted/bubbly texture may be from too oxidizing of a flame and just excess scale being formed, are you hammering it too cold/when there is no color left in the steel?

[Vandle]

Sometimes I'm hammering lightly to take out any bending in the steel before returning to heat, but I thought you could tidy up metal when dark?

I do have the steel directly under the flare, should it be to one side in the gas forge?

 

[Frosty]

If you're only heating to bright red and it's blistering the surface like that the flame is oxidizing. The excess oxygen in the forge could be burning your steel. The higher the carbon content the lower the melting and burning temperature.

Bright red is close to putting it back in the forge temperature, I'm thinking the cracks are from forging cold.

We're discussing forge burners in the "Burners 101" thread, if you post pics of your burner in operation we might be able to help you out. A pic in the forge when you light it, one when it's as hot as it'll get. and one across the opening with a dark background so we can get a look at the exhaust. Oh, and a picture of the whole burner so we know what you're working with.

Frosty The Lucky.

[Vandle]

OK , will do tomorrow.  If you're THE Frosty, then it's one of your T-burners!

It's a 1" 3/4" 1" T with no control over air inlet.

[ThomasPowers]

OK lots to dig through here: 

You do realize that different alloys require different forging temps; what may be great for one can result in total destruction of another? (Ask me about the first time I was forging H13 and "cottage cheesed" it...)

Do you set your forge up to have a reducing atmosphere when forging knives? (and beware of extra CO when using it!)

In general DON'T HIT KNIFE GRADE ALLOYS WHEN THEY ARE NOT GLOWING!

Are you not leaving the blade in the forge for long times?  Working it as fast and in as few heats as possible? (Helps with grain growth, scaling and decarburization.)

Break that blade and examine the grain size; large grain indicates too hot for too long. Please show it to us if possible.

(yes he's *that* Frosty...)

[Vandle]

OK. I have no idea as to how I have the forge set up regarding CO.  Doors are always open and I have a CO detector close by. Now you are talking to a real new boy here, despite his 64 years, so a lot to learn.

Point me in the direction where I can understand what a reducing atmosphere, and what I need to do to control it is please.

I do leave it in the forge for quite a while as the metal cools so quickly.  From video's I've watched, blacksmiths seem to be working metal for longer than I do.  Less than a minute each time.

I'll check grain size tomorrow.

 

[Jclonts82]

like Frosty said, burner topic, has lots of pictures and examples... grab a comfy chair, LOTS of valuable info in there. I read it, ALL OF IT, and the corresponding forges 101... twice... before I built my current setup

 

[Vandle]

I guess I'm a typical amateur - threw it all together and hoped for the best. 

Many thanks guys for all of this.  I'll spend some serious time on this to get to grips with it. 

John

[ThomasPowers]

You do have a good through background in blacksmithing before moving to knifemaking?

Atmospheres can be Oxidizing, Neutral or Reducing:

Oxidizing means there is excess Oxygen left over after the burning and hot oxygen loves to combine with hot steel forming scale. (Or with carbon in the metal forming CO and CO2)

Neutral means that the burn is neutral---neither excess fuel or excess oxygen is left over

Reducing means you have excess fuel and so more CO is possible but it won't scale or decarb your workpiece---it can in fact add carbon to your workpiece!.

Adjusting your burner to create a particular atmosphere is best left to the burner boffins...of which there are a gracious plenty here.

Forge doors or smithy doors?

Forge efficiency usually goes way up if you can close it up as much as possible, even firebricks stacked on the ends will help a lot.  NA burners do require exhaust space to work however.

Doors to the smithy being open are a great thing and the CO detector even more so!

The faster and harder you hit it the longer the metal will stay warm as hitting it puts energy into the metal.  Preheating your anvil and tools can help.  I have a friend that uses an electric clothes iron to preheat his anvil---especially in winter. I heat up a slab of steel and lay it on the face of the anvil  and may put the face of the hammer on top of the slab too.

A lot of issues with going directly to bladesmithing get worked out by learning basic smithing: hammer control, heat and beat times and timing, etc.  Not a necessity; but it cures a lot of frustrations!  Some of my students want to jump ahead and if they are obnoxious enough I'll let them!  Only takes a blade or two before they realize that what I was teaching them about hammer control and forging temps are critically important when you get to bladesmithing.  (One filed for 6 hours trying to smooth out his blade from bad hammering and then realized it was too thin to use as a knife...)

Suggestion for jumping in:  Get a automotive coil spring (with as few miles on it as possible),  Cut down a diameter giving you a dozen to a score of "(" pieces  I use an angle grinder, or a tourch, or a hotcut, or an X-Ray laser, or... Now you have a lot of the same alloy and you can experiment and learn what it requires for forging and heat treating---especially for heat treating you will want to break a lot of blades and *SEE* what's happening.  Keep notes. Don't try to jump from one alloy to another until you learn what works and then try adjusting it for a different alloy.

I'm only 61 right now but have been smithing for 37 years; don't worry I knew a professional smith who was working into his 80's and a fellow who would still smith from time to time in his 90's...

[Vandle]

Started with rebar and made a few tongs until I was fairly comfortable with some very basic techniques.  Made a few church candle holders no problem ( I keep bees so plenty of wax). Forge is squeezed in to my garage entrance, so very wide doors right where the forge is.  I had a TIA 6 weeks ago (unrelated to blacksmithing) and spent a night in hospital, so very conscious of lack of oxygen to the brain. 

I've been practicing thinning and extending metal, but my German anvil has sharp edges so have been using the horn to extend metal.  It seems working mild steel is straightforward - moving to another steel caused the problem.  Maybe I should stick to blacksmithing for a little longer.  I'll try heating the anvil - It hasn't been much above 8 degrees so far this year (centigrade). Doesn't that need a massive heat capacity?

I need to make some hardy tools anyway.

 

[ThomasPowers]

Just warm to the touch helps a lot; there are a bunch of tricks to working in cold temps---like not resting the workpiece on the anvil, instead holding it just over and letting the hammer blow put them in contact---but that's a lot trickier than just warm it up enough it's pleasant to the touch. (We used to fight over who got to sit on the anvil between heats in cold weather...)

Year before last I had 4 syncopes, two resulted in concussions due to my head not being harder than a concrete floor.  I think you will find that a number of folks on this site understand such issues very personally!

My friend with the iron said he would turn it on the hot setting and place it on the anvil face when he walked into the shop and then would go do the set up work for the day's forging and by the time he was ready to put hot iron on the anvil it was warm to the touch.

[Vandle]

Yes - I tried holding wok off the anvil and when it works it's a great satisfaction bouncing the work, but a technique that will take a while to learn consistently. I'll give the hot anvil a go.

[Frosty]

I'm a TBI survivor, I was felling a birch tree for firewood and it kicked back. I became aware again about 3 weeks later in intensive care and got to go home almost 3 months later. 

We'll get you up to speed with this stuff. It's just a little knowledge and a lot of practice. 

Oh, yeah, I put the T burner together so folk wouldn't need a lot of shop equipment or skills to have a working propane burner. 

Frosty The Lucky.

[Vandle]

Forge set up with door closed.  6 ceramic kiln bricks top and bottom, two each side, inner lining of ceramic wool and cut down ceramic bricks as inner replaceable liners.

Garage doors kept shut to keep things darker. 

Front entrance when just lit.

VID_20180414_105139.mp4

[Vandle]

After 5 - 10 minutes with an old oily file.

Temperature that I start to work at. When the tip dulls to black and the centre is still cherry red I return it.  Sometimes I'll lightly work it black to smooth out any large deformities.

Normally, after 30 minutes with the front door down, the exhaust is blue.

One final question, i tried welding metal unsuccessfully and found that the Borax turns the ceramic brick into toffee.  The manufacture recommended a Zirconium paint, but they only sold it in quantities large enough to do 50 of these forges at least - and at $70 a time.  Any other way of protecting the lining from Borax? 

[ThomasPowers]

Tray of cheap clay based cat litter,

As cameras and eyes are not calibrated the same---not to mention monitors and picture software it's very hard to make good estimates on the internet; but you may be overheating for a file alloy; I'd go pie cherry orange and NOT yellow.  For true mild steel I love a good yellow and for wrought iron yellow to white usually works well.

[Vandle]

Many thanks Thomas. I'll try the cat litter.  The camera does show the metal as slightly yellower than it is, and we all see things differently anyway, so the reason I've been starting at this temperature I guess is that I see so much general smithing done at this sort of temperature. I have tried hammering a leaf spring and get absolutely nowhere unless I get the temperature as high as I can.  Big muscles I never had - so that's a bit of a disadvantage.

Sounds like a few of us are getting head related problems for one reason or another - and there's me worrying that blacksmiths end up getting burned. None so far!

[Frosty]

The "dragon's breath" flames coming out the forge opening say it's burning slightly rich. It's unburned fuel burning to make dragon's breath. It's probably close enough for now but use it with the garage door open the orange flame says CO is being generated at a high rate. 

Modern blacksmiths are all head cases, some of us just have a medical excuse.   Truth is I had no idea how common head injuries are till I joined the ranks. 

Frosty The Lucky.

[Vandle]

Many thanks Frosty - I kept the door shut for the camera.  I'll give the 101 thread a good study.

John

[ThomasPowers]

A lot of general forging habits are guaranteed problems when forging higher carbon/higher alloys steels and yes they do tend to be a lot stiffer under the hammer which is why the larger hammers and POWERHAMMERS come into play. 

[Vandle]

Would love to use a power press or hammer, but I have no room and limited budget. This is a hobby rather than a business, and regulations won't let me build any additional buildings as I live in a listed 17th century thatched cottage - not allowed to do any changes to the building or anything in the property boundaries. 

[ThomasPowers]

Go with the "listed era" methods---get strikers!