We recently had a customer of one of our dealers who did not want to buy a stainless steel sink because he believe true stainless steel was not magnetic. He is right… and wrong.
Here is part of an article from Scientific American on the magnetic properties of Stainless Steel:
“The most popular stainless steel is Type 304, which contains approximately 18 percent chromium and 8 percent nickel. At room temperature, the thermodynamically stable crystal structure of 304 stainless steel is bcc; nevertheless, the alloy’s nickel concentration, as well as the small amounts of manganese (about 1 percent), carbon (less than 0.08 percent) and nitrogen (about 0.06 percent), maintains an fcc structure and therefore the alloy is nonmagnetic. If the alloy is mechanically deformed, i.e. bent, at room temperature, it will partially transform to the ferritic phase and will be partly magnetic, or ferromagnetic, as it is more precisely termed.” full article click here
When formed a sink is mechanically deformed as presented in this article and is why a magnet will stick.