Molybdenum increases the strength and hardness of cast irons by depressing the pearlite transformation temperature. It also increases elevated temperature strength and creep resistance. High chromium irons, containing 2-3% molybdenum exhibit significantly greater impact toughness than Mo-free grades and are ideal for severe abrasive conditions like those encountered in mining, milling, crushing etc. These cast irons have acceptable properties as cast. This eliminates the need for a costly heat treatment and makes them a cost effective alternative to other grinding materials. Reduced levels of austenite formers, such as nickel and manganese, also minimize the retention of low temperature austenite - a potential cause of premature failures.
There has been growing interest in the use of high silicon-molybdenum ductile irons with up to 4% Si and 1% Mo. Their good strength up to 600°C makes them a viable and cost effective replacement for more highly alloyed irons and steels in elevated temperature applications such as turbocharger housings, engine exhaust manifolds and furnace components. The austempered nodular irons develop a unique microstructure capable of strengths in excess of 1000 MPa (145 ksi) with good impact toughness. Their exceptional properties are ideal for critical applications such as the large gears and crankshafts required for power generation, ship propulsion and large mining equipment.