High Temperature Compression Studies of Ti64 and Ti407 Alloys using Dilatometer

Ti64 and Ti407 alloys were compressed at temperatures 700C, 850C and 950C and strain rates 10-2, 10-1 and 1 s-1 to 50% height reduction using TA Instruments DIL805 Compression Dilatometer. The cylindrical samples measured 5 mm diameter and 10 mm length. The Ti64 alloy was machined from the top of an as-received forged Airbus testpiece with a bimodal microstructure. The Ti407 alloy was machined from the edge of a forged TIMET testpiece with a lamellar microstructure. Al2O3 platens were used throughout all tests to minimise temperature differences between the end and centre of the samples, except at 700C in Ti64 which used Si3N4 platens due to the higher material yield strength. Temperature was controlled using an S-Type thermocouple welded to the centre of the samples, along with another two thermocouples welded to the end and between the end and centre of samples to monitor temperature differences. Mo disks were attached to the ends of the samples to further reduce temperature differences at the ends of the samples, along with graphite lubricant to reduce friction. The alloys were deformed in an inert He gas atmosphere.