BÖHLER P558

BÖHLER P558 is a high nitrogen 11%manganese-17%chromium-3%molybdenum-nickel stainless steel for surgical implants. Metallurgical requirements include a delta ferrite-free, fine-grained austenitic microstructure with low inclusion content and resistance to intergranular corrosion.

BÖHLER P558 exhibits pitting and crevice corrosion resistance much better than the reference material of Specification F138 and exceeds the material values given in Specification F1314 and Specification F1586. The biocompatibility tests for this material were positive and met the requirements of the test standards used.

The chemical composition of this steel has a high carbon content, together with high nitrogen content. The high carbon content is considered critical in conventional metallurgy of chromium-nickel stainless steels. In nitrogen-rich stainless steels, the carbon replaces the nitrogen, making it a strong contribution to the stabilisation of the austenitic phase. The simultaneous alloying of nitrogen and carbon has a beneficial effect on corrosion resistance and extends the range of austenite stability towards lower solution heat treatment temperatures, leading to better toughness properties.