BS in Materials Engineering
Materials Engineering Department
Ti-6Al-4V is an alpha-beta titanium alloy system, which contains both alpha and beta phases at room temperature. Both alpha and beta phases provide Ti-6Al-4V a range of different properties for a range of applications. In order to improve the energy efficiency and better satisfy customers’ requirements of less than 52% primary alpha phase, Weber Metals sponsored this project to study the effects of carbon content, forging temperature, and cooling rates on primary alpha formation in Ti-6Al-4V alloys. There has been a lot of discussion as to whether or not carbon, a known alpha stabilizer, will affect the microstructure in small percentages. High and low carbon Titanium forgings, .025%C and .007%C respectively, were received from Weber Metals and were sectioned to approximately 1 in3. Prior to heat treatment the samples were drilled to fit a .062-inch thermocouple that would monitor the rate at which the Titanium cooled, as cooling rates affect how the microstructure forms. Samples were heat treated at 1725°F, 1750°F, 1775°F and 1800°F and cooled with three different cooling methods, and analyzed metallographically using Photoshop. Weber Metals uses an image-processing tool for quick estimates on alpha and beta phase content. Photoshop is a powerful tool that will speed up their analysis process and give more accurate readings on microstructures. Carbon content was found to have no statistically significant effect on the microstructures, while air cooling produced the least primary alpha within the cooling rate grouping, only by about 6%. Finally, as the heat treatment temperature increased the primary alpha formed decreased significantly.