Nanostructured nickel-free austenitic stainless steel composites with different content of hydroxyapatite

► Ni-free austenitic stainless steel/hydroxyapatite composites were produced. ► Nanocrystalline structure was confirmed by three different techniques. ► Nitriding of the surface slightly increases crystallite size. ► The mean grain size of the obtained materials do not exceed 100 nm.