Study for Finding Optimum Conditions of Hot Forging of Manganese Aluminium Bronze Cast

The aim of this research was to study the effect of hot forging temperature on the mechanical properties and microstructure of manganese aluminum bronze castings. The castings had a composition according to the C95700 ASTM standard. Voith-Schneider propeller blades 1:10 scale were produced from the castings by hot forging in closed die with flash. The forging was conducted at 400 tons at temperatures of 700, 750, 800 and 850 degree C, followed by cooling in air under ambient conditions. The dimensions of the blades were 19 x 53 x 8.5 mm. Tensil testing specimens were milled from the blades, and additional specimens were polished for hardness testing and microstructure observation. The result of tensile testing revealed that the yield stresses were 587.28, 531.29, 529.68 and 432 MPa and the ultimate tensile strengths were 718.08, 701.49, 683.94 and 650.32 MPa, at forging temperatures of 700, 750, 800 and 850 degree C, respectively. The average hardness were 193.55, 193.17, 192.86 and 193.73 HB, respectively. The hardness increased from the large end to the small end of the specimens.