316 Stainless steel property question

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My company produces explosion proof boxes for hazardous areas. Recently, a customer asked for 4 boxes to be casted in 316 stainless steel. We just received them today but the boxes are attracted to magnet and seems to be a bit rusty too. My question is whether this is normal? I’ve always thought that 316 SS cannot be magnetized and wouldn’t rust. If I use a magnet on 316 SS rods, they will not be attracted. Why?

Thanks for your time


316 Castings are chemically formulated to provide a mixed microstructure of ferrite (ferromagnetic) and austenite (non ferromagnetic) to preclude hot cracking and enhance “castability”, while wrought 316 SS products are generally formulated to be 100% austenite. Ferrite content of 316 castings are often in the range of 10% to 15%, which is permanent in the casting. General corrosion resistance of the casting will not be equivalent to that of properly solution treated wrought 316 SS product. It is assumed that your castings have been solution treated.