تاثير افزودن منگنز بر فرآيند رشد در آلياژ برنج 30-70 متبلور شده

Grain Growth Kinetics of 70-30 Brass Containing Mn

In this research, 70-30 brass containing 0.25% Mn was prepared using a controlled atmosphere furnace and cast in a copper mould. Samples with 5x10x50 mm dimensions were cold rolled in order to reach 65% reduction. Then specimens were isothermally annealed at three different temperatures (600, 700 and 800°C) with different holding times between 2-60 minutes and were then cooled in 20°C water. Microstructural studies were executed using optical microscope. The average grain area of 200-450 grains was measured using Clemex image analyzer software. Results showed that addition of Mn to 70-30 brass had an impact on grain boundaries atmosphere and also decreased its activation energy and consequently accelerated grain growth. Calculation of growth activation energy within 500 and 700°C showed that growth activation energy of Mn free brass was 171 kJ/mol while that for Mn containing alloy was 22.35 kJ/mol.