km69stang Posted May 2, 2011 Share Posted May 2, 2011 Ok, so I decided to see what my new forge can do, and I decided to create a temporary crucible from 3 inch Schedule 40 Steel tube and a 1/4 in thick plate steel, with a few washers welded to it for manipulation. I decided to melt brass that I have laying around and cast it into ingots. I figured this was safer than attempting to weld after just getting the forge built, and not exactly knowing what to do in forging. I just wanted to see the potential heat that I can achieve. I was able to melt the brass with some ease, as stated in another post, but I encountered the oxidizing of the steel as stated in other postings. I scoured this specific forum and even searched for the work 'oxidize' and 'oxidization' and read everything, and am still not sure of the right method. I did this before asking as to not be bombarded by, 'you should have read the other posts on this subject.' Now, my question is, what should the atmosphere be like, as best that can be described, to prevent oxidation of the steel? Should there be more of the 'Dragons Breath' bellowing out of the forge, as in more gas in the mix than in optimum burn mixture? I don't want to create more rust than a finished project when i am trying to forge. I am trying to make sure that I am clear on what I am asking, and I know that this is a NOOB question! Thanks much. Kyle Quote Link to comment Share on other sites More sharing options...
Glenn Posted May 2, 2011 Share Posted May 2, 2011 Safety First Brass is a yellowish alloy of copper and zinc, sometimes including small amounts of other metals, but usually 67 percent copper and 33 percent zinc. Alloy of copper and zinc, important for its hardness and workability. Brass was first used c. 1200 BC in the Near East, then extensively in China after 220 BC, and soon thereafter by the Romans. In ancient documents, including the Bible, the term brass is often used to denote bronze (copper/tin alloy). The malleability of brass depends on its zinc content; brasses with more than 45% zinc are not workable. Alpha brasses contain less than 40% zinc; beta brasses (40 – 45% zinc) are less ductile than alpha brasses but stronger. A third group includes brasses with additional elements. Among these are lead brasses, which are more easily machined; naval and admiralty brasses, in which a small amount of tin improves resistance to corrosion by seawater; and aluminum brasses, which provide strength and corrosion resistance where the naval brasses may fail. Safety First The zinc can separate from brass welding rod when it got too hot during welding. Please read up on the problems of zinc, fume fever, heavy metal poisoning, etc There are certain mixtures of brass that you do not want to mess with due to the content. Quote Link to comment Share on other sites More sharing options...
Fosterob Posted May 2, 2011 Share Posted May 2, 2011 I am not an expert here but I understand that if there is dragonsbreath (flame) coming out the door there is no oxygen in the forge to oxidize anything in it. If there is no flame out the door then there is more oxygen in the forge than gas to burn it up. Adjust your mixture to be more rich and you should be OK. With melting brass just don't get it above the boiling point of zinc and generally you should be OK. Rob Quote Link to comment Share on other sites More sharing options...
km69stang Posted May 2, 2011 Author Share Posted May 2, 2011 Glen, with the melting of the brass, it was the only metal that I had in abundance that I would be able to melt and be able to cast. I was and am aware of the zinc fumes, and so I had 2 box fans running, one forcing air in through a window, and the other pushing it out the door, plus an exhaust fan I installed at the to of the garage. As i said, this was just to test what temperatures I could get, and since brass melts at about 1650 to 1700 F. I decided that it would be a good indicator of what it is possible to achieve. Not necessarily the BEST way, but I have no access to a digital thermometer of that kind of range. I want to be able to weld in this, or at least, draw enough first hand knowledge to be able to build another capable of doing so. I have read enough material to know that VAPORIZED ZINC IS BAD JUJU. I am in the works of a design of a 'fresh air helmet' that is connected to a regulated air line from an air compressor. I believe that this can serve several purposes: keeping toxic fumes from entering my body, acting as a face shield by keeping welding and molten metal spatter from spraying on my face, keeping my welding helmet from fogging up because I breath heavy (fat guys do that), and keeping my head cool in the summer heat and preventing all that sweat from getting into my eyes! It may look weird, but, safety and comfort is my main concern behind this. I worked in a factory that had a air-fed face shield in the grinding booth, that covered the head and neck with thick denim to keep the flying metal shards out. It was nice not having sharp metal in my hair when I went to take showers. No metal splinters!!! Quote Link to comment Share on other sites More sharing options...
Glenn Posted May 2, 2011 Share Posted May 2, 2011 I am in the works of a design of a 'fresh air helmet' that is connected to a regulated air line from an air compressor. You may want to research this before putting it into practice. You will be breathing oil, dirt, dust, and a whole mess of other things from the compressed air. As I recall, there are special precautions and filters used in fresh air helmets. Just trying to keep you safe. Quote Link to comment Share on other sites More sharing options...
km69stang Posted May 2, 2011 Author Share Posted May 2, 2011 Thank you for the heads up, Glen! I did not know that. I will do more research on that. Quote Link to comment Share on other sites More sharing options...
ThomasPowers Posted May 2, 2011 Share Posted May 2, 2011 Fosterob, The melting point of brass is smack dab at the boiling point for Zinc, add in the necessary superheat to be able to pour it and you are over the boiling point for zinc. Zinc "burn off" is a given when casting brass and you need to take care both to remove the fumes *and* to replace the zinc as it helps the pourability of the alloy. (for small amounts new pennies make a nice zinc add.) What is stranger is that the smelting temp for zinc is over it's boiling point/recombination temp make it a difficult metal to smelt in earlier times. One methodology used in medieval India was to smelt it in an alembic where the gaseous zinc metal was "piped" to an oxygen poor area to cool and solidify as a very fine zinc powder that could then be melted into zinc ingots at far lower temps. In Europe zinc was mainly used in it's ore state and Biringuccio in his Pirotechnia talks at length of "colouring copper" by heating it in the presence of zinc ore. As for positive pressure face masks a compressor is terrible to use. All you need is a good fan located in a "Clean air location" Usually outside the shop . SCREEN it to keep the odd wasp from being delivered in a foul mood into your helmet. Why put hours wearing out an expensive piece of machinery when a cheap one will work better? A lot of knifemakers have set these up to use when grinding and you might find some examples on knifemaking forums. Quote Link to comment Share on other sites More sharing options...
Fosterob Posted May 3, 2011 Share Posted May 3, 2011 Fosterob, The melting point of brass is smack dab at the boiling point for Zinc, add in the necessary superheat to be able to pour it and you are over the boiling point for zinc. I knew they were close but wasn't sure how close. Thanks for the heads up. The fresh air systems I have used have an oiless compressor to provide the air. Seems a good forge blower would also provide the needed pressure to get to the mask. Rob Quote Link to comment Share on other sites More sharing options...
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