Influence of Hot-working and Solution Annealing on Microstructure and Mechanical Properties of Haynes 188

In present work effects of strain in hot working process and solution annealing, on microstructure and subsequent mechanical properties were investigated. The billet were hot rolled into final reduction in thickness 60 and 85% (R-60 and R-85) at 1150 ˚C. After that, solution annealing at 1140 ˚C to 1200 ˚C for 10 to 120 minutes were conducted to optimize of mechanical properties. The microstructures revealed grain size of R-85 sample was lower than another, but grain growth was observed for annealed sample above 1140 ˚C after 30 minutes. EDS analysis shown M6C carbide rich of tungsten is only precipitated carbide. It's also found that grain growth rate is much more for R-85 sample. SEM evaluations also confirmed faster solution rate of carbides for R-85 sample. Yield strength of R-85 is very higher relative to R-60 while after annealing at 1140 ˚C for 10 minutes it decreased drastically. Annealing in same condition for R-60 sample cause not only decreasing of strength, even improved ductility.