The solid structure of the iron has two kinds, one kind is the face centered cubic, called the austenite, one kind is the body core cube, is called ferrite. General steel at room temperature are ferrite, can be attracted by magnets. There are a variety of stainless steel, the most common is the chromium and nickel austenitic stainless steel, such as 0Cr18Ni9. Containing 18% chromium and 9% nickel, the stainless steel magnetic is very weak. But does not contain nickel or low nickel chromium stainless steel, martensite stainless steel, such as Cr12. They are magnetic, corrosion resistance than austenitic stainless steel. In due to soaring nickel prices, so some bad shoddy manufacturers, martensite stainless steel instead of austenitic stainless steel, so can carry a neodymium iron boron magnets to check the stainless steel, so smoking is certainly not a good.