ME2151-1COOLINGRATEEFFECT.doc

ME 2151-1 COOLING RATE EFFECT SESSION: 2009/2010 1. Objectives To study the effect of cooling rates on the microstructure hardness of 0.45% carbon steel 2. RESULTS (2a) Results Of Observations On The Microstructures of Specimens Below are the results obtained for the observations on the microstructures of the various specimens used during the experiment, and all the important phases are labeled. Specimen D1 Furnace Cooled. 400 ( Specimen D2 , Air Cooled. 400 ( Specimen D3 Fan Cooled. 400 ( Specimen D4 Water Quenched. 400 ( (2b) Results of Rockwell Hardness Test On Specimens Read mg1 Vickers Number Read mg2 Vickers Number Read mg3 Vickers Number Read mg4 Vickers Number Average Vickers Number deviation Cooling rate(oC/s) Furnace Cooling 83.0 163.9 83.0 163.9 81.0 157.7 79.0 151.0 159.1 8.1 0.01 Air Cooling 94.0 213.8 94.5 216.9 94.5 216.9 93.5 210.6 214.5 3.9 0.3 Fan Cooling 96.0 225.9 95.5 222.9 94.5 216.9 94.0 213.8 219.9 8.0 15 Water Cooling 59.0 675.0 59.5 686.0 59.0 675.0 58.0 654.0 672.5 16.7 480 3. DISCUSSIONS AND ANALYSIS OF RESULTS (3a) Comments On The Observed Microstructures And Effects Of Cooling Rate On Microstructures The physical properties (color, crystalline form if solid, density, etc.) may differ widely, but identical chemical compounds can be formed from the various allotropes of the one element. In this very experiment, we are considering 0.45% carbon steel, and therefore only need to look at the Fe-C phase diagram up to around 0.45 % C. The effect of rate of cooling is studied using samples of different cooling rates but with the same carbon content. We will use samples D1(furnace cooled), D2(air cooled), D3(fan cooled) and D4(water cooled), which have 0.45% C to study this effect. The microstructure of D1 (furnace cooling) consist largest of white space and dark space. Which means material stands under temperature between