Cost competitive machining of ADI after heat treatment has been a normal practice for about twenty years. In order to be successful with machining after austempering all the metallurgical processes, both in the liquid and solid states, must be carried out at the best level of available technologies, involving all necessary investments to ensure consistent and reproducible quality. A high nodule count and a narrow range of hardness are the first indexes to be monitored. This will ensure the safety of the casting design. Research programs on material properties and material design, together with the success of running applications, are increasingly indicative of the high potential of ADI as a benchmark material for engineering applications. Metallurgical processes applied to castings are based on the unique relationship of spheroidal grade and silicon. This relationship allows us to produce the intermediate structure in austempered cast irons, knows as “Ausferrite”. When compared with steels, ADI castings are less dense, less likely to crack and have excellent wear resistance. Being a multi-phase, high performance material, ADI’s process window is narrower than other conventional materials. For this reason, ADI processes require large investments in the foundry and heat treatment, with maximum integration between engineering design and machining operations.
