RESULTS AND OBSERVATIONS: As the electrical current passed...

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CIVL2110 – Materials Executive Summary, 2017 EXECUTIVE SUMMARY 1. INTRODUCTION AND OBJECTIVES The two experiments conducted were designed to observe the process of phase transformation and provide insight into the properties of different phases in steel. Experiment one involved heating a wire of eutectoid (0.76 C wt.%) steel to reveal the effect of phase transformation on the elongation of the wire. Theoretically, on heating the wire to 723 0 C, the wire undergoes a eutectic phase transformation from pearlite to austenite, altering its crystal structure and density. By tracking the elongation, one is able to observe the phase transformation that occurs, and how this changes the length. Experiment two tested the hardness of various steel specimens with different microstructures. These results were used to provide insight into the material properties of these microstructures, the effects of different tempering methods on steels, and of changing the weight percentage of carbon. Understanding different phases, microstructures, and how these are affected by tempering is critical for engineers. Being able to manipulate the various properties of different steel phases allows for more design versatility, and the ability to safely create materials assured to be of certain hardness, strength and ductility. 2. EXPERIMENT ONE 2.1. PROCEDURE Experiment one was conducted using a 2m (approximate) steel wire, two bolted wall supports, electrical wires, a generator, a suspended weight and a 1m ruler. The steel wire was suspended from the supports. Electrical wires were attached to the cable and generator using steel clips. The weight was attached midway along the wire, and the ruler balanced vertically behind it (see Figure 1). Bolted wall support Small generator Electrical wires Steel Cable Steel clip Suspended weight 1m ruler Figure 1: Schematic Diagram of Experiment
CIVL2110 – Materials Executive Summary, 2017 The generator was turned on to introduce an electrical current into the steel wire, and turned off when the steel was red-hot. The movement of the weight was tracked throughout the experiment by inspecting the ruler behind it. 2.2. RESULTS AND OBSERVATIONS: As the electrical current passed through the steel wire, the inherent resistance of the steel to the current heated the wire, causing it to expand. As it expanded, the suspended weight began to descend. This descent was interrupted by a short, abrupt ascent, before continuing downwards. The generator was then turned off, and while ascending to its original position as the wire cooled it was interrupted by a similar abrupt descent. This was more obvious than the abrupt ascent during heating. The approximate vertical displacement of the weight was measured to estimate the elongation of the wire. The abrupt shift of the wire was approximated by comparing the amount the weight sharply ascended to the overall descent, and vice versa. The weight shifted approximately 1-2cm upwards while heating, and descended 3-4cm when cooling, as

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