Metal cutting blades run much slower than wood cutting blades. If you are running a constant speed saw that runs around 3000 ft/min blade speed it is hard on the blade and generates more heat than the blade can handle. You need to run at about 200 ft/min or less speed to be effective and then keep the metal fairly thin, 1/6 in. A true metal cutting band saw usually has a coolant that is sprayed on the blade to keep it cool so it doesn't lose its temper.
You might check for a company in your area that makes band saw blades to order.
I found one that made one for my saw and it cuts through steel, aluminum plate. I've cut up to 1/2" steel.
You have to remember that some saws aren't made for heavy metal cutting and you have to feed the metal accordingly. Also the metal cuttings can get into the saw and must be kept cleaned up.
The blades they made for me have lasted for 4 years and I use them on wood also.
I had a blade for a year and put in a bind and snapped the blade at the weld. I went back and they re-weld the blade free. I'm still using it.