Steel and Steel Forging. The Flower Pot Furnace
For anyone interested in doing a little bit of home metal forging and whats to find a cheap and easy way to do it then look no further. Steel is a very useful metal and is used for almost everything around you. High temperatures are needed to melt steel and also safety is very important as you can be left injured for life if you go wrong.
The Flower Pot Furnace, as suggested by the name, is a home furnace you can make out of a large clay flower pot and a few other items you can easily and cheaply aquire. However it would be irresponcible to tell you how without first taking you through proper safety procedures and equipment and also teaching you a little about metal, in particular Steel.
Steel is a metal alloy made out of mainly Iron (fe) and Carbon (C), the carbon content is only ever between 0.2 and 2% and brings different properties to the steel giving it different uses. Carbon acts as a hardening agent in the Iron and the more you add the stronger the metal becomes and decresses the melting point by about 100 C. Steel high in carbon is stronger and stainless steel is always high content. However adding to high amount of Carbon can make the Steel brittle and less ductile. The Japanese sword smiths were the first to discover that making a sword sharp, strong and hard required different types of steel in one blade.
Low carbon steel is alot better at holding its sharp edge without dulling quickly, but was to weak to make a whole sword out of. So by wrapping high carbon in a low carbon shell, sword smiths were able to develope a technique for tempering steel which has never been improved apon.
When 0.7% steel is heated beyond its critical temperature, 750 C, it enters its Austenite phase. This is when the Irons structure ‘opens’ and allows the carbon and iron form together into steel molecules. Then rapid cooling or quenching, changes the form of the steel one more time where it ‘locks’ back together into its final structure. This is know as Martensite.
At around 0.8% the steel starts to become more brittle and noticably so, but its stronger structure still allows for it to be useful and was used as the edge of blades.
Properties of Steels.
Stainless 440 - Cr+ni+mn+C Melts at 1363 C
High Carbon 0.8%+ Melts at 1356 C
Medium Steel Melts at 1427 C
Low Steel Melts at 1464 C
Steel is about in the middle on the charts of melting points for steel. Lower melting point metals include
Aluminium (Al) 659 C
Gold (Au) 1063 C
Lead (Pb) 327 C
Magnesium (Mg) 670 C
Titanium (Ti) 1795 C
Tungsten (W) 3000 C
So steel is a cheap and effective mix and becomes manageable at reasonable to achieve temperature. If you want to use a different metal the i would recomend you look at a complete list of melting points. Keep in mind what you are making however because if you went for the convenient tempertures of Aluminium then remember its a weaker, lighter metal and has a soft feel to it. However remember to stay away from lead as it is expensive, dence and of cause extremely poisonous and should not be attempted. Lead is used in roof lining and sadly was also used to seal food can in america until 1980‘s. It was also used in pertol and has caused masses of damage to the planet and is the causes of over 10 million cancer cases. Lets stick with our friendly steel outside of real factories. Also lead is horrible to work with and soft and wont keep features impressed onto it.
That was a pretty basic explaination of steel and how its processed and there is alot more to know. Metallurgy is a fascinating subject and a fine science to learn so if you liked this and want to be better at what ever it is you do with metal then please educate yourself with books.
