MANUFACTURE AND PROPERTIES OF HEAVY THICK -WALLED OPEN-DIE FORGINGS OF THE LOW-ALLOYED TITANIUM TI-0.3MO-0.8NI FOR CHEMICAL-PLANT CONSTRUCTION

The low-alloyed titanium grade Ti-0.3Mo-0.8Ni, ASTM/ASME Grade 1 2, ex hibits improved corrosion resistance, higher strength and permits high er design loads than unalloyed grades. This combination of properties has led to an increased economic interest in this alloy. Thick-walled heavy open-die forgings cannot be considered as standard-components. N evertheless, they must comply with the standard material requirements in order to benefit from the advantages of the Grade 12 alloy. By sett ing an optimum composition of the vacuum-melted ingot in conjunction w ith suitable forming and heat treatment parameters it is shown that th e desired characteristics can be reached with a high rate of repeatabi lity with properties nearly equivalent to those of thinwalled forgings . The review of the properties of low-alloy Grade 1 2 titanium parts i s followed by a comparisation with the characteristics of common unall oyed titanium grades at room temperature and elevated temperatures.