Scrap Steel Pour 5/5/11
David Fields (Artist), Allen Peterson (Professor), Stephen Bodner (Shop Manager)
Written by David Fields
This is a real ”scrap metal” melting. The scrap metal parts and pieces are from the collection of David Fields. All the parts and pieces have been collected over a 10-year period. All parts and pieces have been photo documented and categorized before being melted.
There were many, many things learned on this day. The first thing being that I was not prepared for the amount of time that this part of my project would take. Nor was I aware of the lack of information available on small-scale steel melting and casting. All the info that I could find was on what the steel industry considers small, 1 ton. I would be using a crucible that would hold 50 pounds of steel. A metallurgist told us that small scale melting was not easily possible. He said that the steel oxidizes when it heats up to melting temperatures and then turns to slag not letting any steel become molten. So in hearing this I thought that the whole Idea of this project might fall through. He suggested and I saw from a couple of large scale melting furnace diagrams that a line of shielding gas be used. Argon is used for shielding gas in mig and tig welding also, makes sense. While researching I also saw a series of steel melting experiments done by melting steel rods by dipping them into a molten steel bath. These experiments will help later in my own project. In my project I wanted to melt scrap metal in three different batch types American, Chinese, and Miscellaneous.
We started the melting process with the Chinese metal and added an argon blast from a hose positioned to the side and blowing into the furnace. I had a whole lot of Chinese angle from ATV and motorcycle crates from china to melt down. I made bonded sand molds to cast ingots out of the steel. We filled the induction furnace with scrap angle and flat steel for the first batch. In this induction furnace the heat/temperature is set by the percentage of wattage used, stainless steel melts at around 30%. In 45 minutes we had moved it all the way up to 70% and the Chinese steel had not started to melt. It was cherry red but that was as far as it would go. I asked the shop manager if we should put one of my thicker chunks of metal (American) in the bottom to maybe make a puddle in the bottom, then the thin stuff might melt better under the other molten metal like in the experiments I had seen. He said its worth a try so we pulled out some of the angle and pushed some 5/8” plate (American) into the bottom.
Watching the plate it almost immediately turned cherry red, then bright yellow, But it was not melting. So I asked, should we put an even thicker piece in because the plate seems to be getting much hotter than the angle? Sounds good to me he said. So I got some really big American pieces that I had cut off of a trailer hitch that were about an inch thick and 6” long and my professor Allan Peterson put those in. Within 5 minutes it was melting so we pulled all of the angle out and started putting in thick American metal parts. It started melting so fast after that that it was burning the metal and shooting sparks everywhere. Stephen the shop manager started turning the furnace down and by the time we poured it was at 20%. When we measured the temp with a pyrometer it was 2850 degrees Fahrenheit. One of the last pieces in was a lawn mower blade whole; it just sank right down into the furnace.
The pour was not as successful as the melt though. There was no slag pulled off of this molten metal. As we begun to pour the liquid metal ran over the side of the pour cup and the metal made contact with the bailing wire straps holding the mold tightly secure. The wire snapped releasing the pressure holding the mold together and the molten metal blew out the back of the 2nd tier of the mold. There was loud popping and hissing then fire and smoke. The molten metal hitting the concrete was popping and it was also melting the hydraulic lines under the furnace. There was lots of smoke and nerves on end. When everything was secure, I broke apart the mold to see what we had accomplished. There were 8 incomplete ingots and 4 good ingots. 4 Good Ingots!!! Not a whole lot of product but massive learning at pouring ingots. I hope to try again in the near future.
I have to convince my professor and shop manager that we can do it safer and quicker with more product as a result. Better binding on the molds and starting off with thicker metal. I don’t have thicker Chinese metal so I propose to forge or weld the thin metal into bigger chunks to load the furnace with.
MORE TO COME!
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