Heat Treatment of Steel

Heat Treatment of Steel

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The Heat Treatment of Steel Engineering 45 (Material Science) Troy Topping 11/29/2012

Kanisha Bristow 11/1/2012

Abstract: We observed how the properties of 4140 steel vary with the heat treatment to investigate the impact they would have on a design project. We prepared six specimens with three different heat treatments, Annealed (O), quenched and tempered (QT), and Normalized/ As-Received (Norm/AR) and each were tensile tested using the universal testing machine (UTM) along with a Rockwell hardness test. From the data collected stress strain curves were created for each specimen and % elongation (EL), % reduction in area(RA), ultimate tensile strength(UTS), and 0.2% offset yield strength(YS) were computed. 4140 O and 4140 O old values are 25.26% and 26.5%, 18.45% and, 42.19%, 28,991,474.20psi and, 28,508,137.50psi, 55,000psi for both. For 4140 QT A and B 13.71% and 12.56%, 52.51% and 47.5%, 29,977,578.79psi and 27,120,022.94psi, 188,082.39psi and 193,841.0712psi, 179,700psi and 186,000psi. For 4140 (AR/Norm) 12.3% and 12.46%, 43.9 % and 25.7%, 28,231,239.03psi and 27,750,052.85psi, 113,889.2psi and 159,705.4psi, 94,800psi and 105,100psi.The significance of these tests is to determine the properties of each heat treatment which in turn could help with future design applications.

Introduction We experimented with the effects of heat treatment on the 4140 Steel on a macroscopic scale. We used three different heat treatments, as-received, fully annealed, and quenched and tempered. We did a tensile test and hardness test on each of the specimens.Fully annealed steel is created by heating the steel into the austenite region which is an FCC phase, and then slow cooling it in a furnace to room temperature. Slow cooling allows enough time for pearlite to form which gives the steel a high ductility but low strength. Whereas the quenched and tempered specimen is acquired by quenching, this is to rapidly cool the steel, preventing the pearlite from forming....

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