Casting a forging-ready sword base

[Kiel366]

Hi!
I buy my materials at a scap yard. Recently I bought some aluminium and some brass. My ultiate goal is to forge a sword. In order to do this I have to melt down the scrap and cast a simple sword base, which I'm gonna forge later.

 

I tried Al first. I poured the metal into my fossil shell flour mould and let it cool down (without adding any water). Then I heated it up a bit (200-300 deg.) and started hammering. Everything was all right until after one hit it just craced. More hammering caused more cracks. I use a stone as my anvil.

 

I'm concerned that sth is wrong with my casts as both Al and brass look 'grainy' when they break apart.

What a I missing? What am I doing wrong? Maybe I heat and forge it incorrectly?

 

I'm attaching a photo of the broken sword pieces.

 

Someone with ore experience please help me.

Thanks.

[ThomasPowers]

The reason you do not generally cast sword blades is that casting produces large grained weak ingots. Forging the ingot can result in grain refinement; However are you using an alloy that is suitable for casting and forging? You also need to lean how much deformation at what temperature your alloy can withstand without cracking and what heat treatment may be required between forging runs.

Generally it is faster and cheaper to buy a plate of a known alloy and do stock removal and then any age (precipitate) hardening.

You still end up with an Al sword that a cheap properly made steel sword will cut chunks out of. It will also be the wrong weight for a sword blade of the size/shape you make it. (The mechanics of sword blades are important to their usability)

If you don't plan to use it as more than a wall hanging decoration , cast to size/shape and be done with it.

[Kiel366]

So how do you get rid of the grains?

 

The reason why I use aluminium is its low melting point. I read Al it's very forgable and rather soft,so I wanted to start with it. I also want to stick to traditional (old, historical) metalworking methods. So the metal ust be somehow smelted and cast before it's worked. How to prepare my material to forging? Maybe it would just be easier if I used bronze or copper?

[Steve Shimanek]

Aluminum is only forgeable within a narrow heat range; too hot and it disintegrates, too cold and it cracks. Try experimenting with scrap pieces first.

[george m.]

Aluminum and brass are not traditional forging materials.  I have never tried to forge Al but brass is pretty much not amenable to forging.  This is because most brass alloys contain some lead to make it softer for cold working or machining.  When heated the lead liquefies and causes the metal to crumble when hit.

 

Bronze usually is forgeable but stay away from beryllium bronze because it can generate heavy metal fumes.

 

Grain size in casting is generally a function of how fast the molten metal cools.

 

My experience is that many young men want to learn blacksmithing so that they can make a sword.  Unfortunately, it isn't that simple.  Forging a steel sword takes some experience but hardening and tempering takes a lot more.  A sword is not a beginner's project, at least a usable one.  Also, the forging and heat treating is only part of the project.  Expect a LOT of bench work filing, grinding, polishing and making the hilt parts.

 

I think that you are better for any blade to use commercial stock rather than melting random scrap which may have any number of weird alloy elements in it.

[ThomasPowers]

If you want to use the methods you need to use the materials. Al has a fairly short history as a "common" material; trying to work it with methods over 1000 years old can cause trouble.

When I forge Al I usually work it pretty cold, even at room temp and I will do a hammering pass and then anneal it, repeat forever. Hammer too much and it will crack, hammer too hot and it will crumble

Most brass alloys are not hot forgable; those that do are forged at around just barely glowing in a DARK room---no lights. Bronze alloys range from being great---like silicon bronze to completely unforgable even the forgable ones need tight temperature control.

However: leaf springs from cars are actually generally a good alloy for swords and usually cheaply and easily found, (try to get newer ones as old heavily used car springs can have fatigue cracks in them)

And "The fastest way to learn to make swords is to learn to forge first and then learn to forge knives and then learn to forge swords" this will let you succeed at things as you go along rather than fail many times as you need to learn the basics to be able to learned the advanced skills!

[Charles R. Stevens]

Unless your looking for a bronze age sword, then copper alloys are aproriate, as is your cast and forge technich. But that is bronze smithing, not blacksmithing, lol in any event brass is not a good material for that and your going to have to talk to the archilogial metalergests as to what alloys were used

[Kiel366]

Is there a way to get rid of the grains? Will instant cooling with water help?

[Charles R. Stevens]

Personaly I dont know, but I Imagine not. Heating to welding temp (if its a forgable alloy) and consolidating may help. Extruded aluminum is a forgable aloy, cast not particularly. Aluminum bar is usualy extruded wile pistons and bearcans not so much.
Welding temp for aluminum Dosnt even glow, just gets sticky

[Frosty]

Is there a way to get rid of the grains? Will instant cooling with water help?

 

I"m afraid you are missing the point of the advice so far. Aluminum is NOT suitable for forging a sword from so getting rid of the grain growth doesn't make a difference. Frankly if you allow grain growth in Aluminum you aren't going to get rid of it short of throwing it away.

 

Another bit of myth you're trying to work with is the whole casting then forging technique. That only works for bronze blades. Trying to salvage bronze scrap has a long list of problems first and foremost being you aren't going to have any idea if it is even bronze. There are many alloys that are "bronze" color but are something else, some alloys are VERY dangerous, beryllium copper being top of the list and it looks just like bronze but the fumes generated by heat or the dust are VERY toxic.

 

Then there's the "traditional" mythos so many folk believe in. If you were actually to learn sword making under the historical period limitations of the bronze age there is NO, ZERO chance you'd start learning metal working by making a sword. You'd start out as a young child in the 5-6 year old range by cleaning, fetching and carrying and generally keeping out of the way. As the YEARS passed you'd progress to standing at the master's side while he worked and listen to what he said eventually you might be allowed to break out molds or maybe forge some simple projects NOT blades. Probably by age 16-17 if you had the talent and worked hard enough you might begin forging basic blades, think dinner wear and decorative elements.

 

And NO there isn't an "aluminum age" where armies were fighting with aluminum weapons. Okay we were fighting with aluminum weapons during WWII but fighter planes aren't quite the same thing as swords.

 

Frosty The Lucky.

[Steve Sells]

until fairly recent time's.... aluminum was more valuable, and much more rare than gold, so I dont know where you got your informamtion, but you are very mistaken.

[Jack-O-Lantern]

1. Aluminum and iron and probably many other metals have a sandy or grainy look when cast then broke. There's nothing you can do.
2. Be very careful with brass. Heating it up and breathing its fumes could kill you.
3. 200-300 degrees is a good temp for breaking what your working on. Even at room temp aluminum will break when you hit it with a hammer. Even steel breaks when red heat fades away and you still beat on it.
4. Work with steel and get it bright orange. Then hit it. Use aluminum for casting a fancy pommel or something.
5. If you don't have an anvil or a big heavy hunk of metal, then buy a sledge hammer and ditch the stone.
6. If you already cast a good looking blade, don't hit it. Either way aluminum won't do anything but look cool.
7. If long complex explanations from vets are boring to you; LEARN WHAT'S DANGEROUS AND AVOID IT. Then find STEEL OR IRON, heat to orange and start hitting. You'll learn what do.

[Jack-O-Lantern]

Oh yeah!!! DON'T INSTANT COOL WHAT YOU CAST!!!!!!!! It will explode in your face!!! Avoid at all costs!!!

[Nobody Special]

Butter melts at low temperatures and is incredibly soft too. It even has the advantage over aluminum that it won't crack. Sadly, it makes for lousy edged tools.

 

Aluminum knives have only really seen limited use, usually as experimental blades that could be exposed to salt water safely (and didn't keep an edge well). It's like trying to build dinner tables out of balsa wood. You might manage it, but way, way more difficult than necessary, and the end product's not worth it.

 

If you're gonna mess around with casting one, maybe bronze at least? Closer to the right weight, and much more castable. Don't quench your casting. Yikes.

 

There really aren't any "historical" aluminum working techniques. To expand on Steve's statement, when they built the Washington monument, they capped it in natural aluminum. 3 ft tall, and around  75 lbs, it represented half of the known aluminum in the world, and was displayed for about a yr in the window at Tiffany's. Most of what was around was used for jewelry making.

[Kiel366]

Hi!

I just wanted to get an answer about Al, because I actually managed to forge 2 blades (the smaller one in the attached picture) without Al breaking (hammering 10h each to form a bar into it). I don't know how to replicate the conditions under I first done it.

 

Today I tried to work with the broken pieces I casted yesterday and to my surprise they were quite hard. They broke, but after like an hour of hammering. The bar I've made my blade of was lying for a couple of weeks. Is it possible that Al hardens by itself after some time? How to make it not break at all during hammering?

 

Now I know about annealing and that I have to use a crucible. Thanks for that. Any other important point I may be missing? How much iron is dissolving into my Al while it melts?

 

BTW: After my ingots broke today while hammering, I got so annoyed that I decided to cast a flat Al plane and cut spear heads out of it. They look terrible but they are.

[Dodge]

Hi!

I just wanted to get an answer about Al, because I actually managed to forge 2 blades (the smaller one in the attached picture) without Al breaking (hammering 10h each to form a bar into it). I don't know how to replicate the conditions under I first done it.

 

Today I tried to work with the broken pieces I casted yesterday and to my surprise they were quite hard. They broke, but after like an hour of hammering. The bar I've made my blade of was lying for a couple of weeks. Is it possible that Al hardens by itself after some time? How to make it not break at all during hammering?

 

Now I know about annealing and that I have to use a crucible. Thanks for that. Any other important point I may be missing? How much iron is dissolving into my Al while it melts?

 

BTW: After my ingots broke today while hammering, I got so annoyed that I decided to cast a flat Al plane and cut spear heads out of it. They look terrible but they are.

 

Where would the iron be coming from?? I am intrigued by this. I wasn't aware aluminum could be mixed with ferrous metal successfully.

[the iron dwarf]

in the local scrapyard they get lots of large steel ladles, big ones that hold maybe a UK gallon each ( 5L about ) normally with a big rough hole eroded in the bottom, they come from a place nearby that casts Al, they are coated in Al

[ThomasPowers]

Hammering work hardens metal. Al is also subject to precipitate hardening; but I'd bet on work hardening.

Did you anneal them after hammering? If you have recast the Al it could be picking up even more impurities from your system and so the more recent ones might have more problems.

Have you visited backyardmetalcasting.com yet? It's a place dedicated to casting and has a lot of good info on casting aluminium

[Steve Sells]

I am moving this to casting, since it really is not about swords, but aluminum casts.

[Dodge]

Did you read post #15 ???

 Mystery solved