Essay about Heat Treatment of Mild Steel

2829 Words Mar 28th, 2014 12 Pages
Title: Heat Treatment of Ferrous
Objective:
To determine the effect of heat treatment on mechanical properties of 1050 Steel.
To reveal the microstructures of 1050 steel during heat treatments.

Abstract
In this experiment, we observed how the properties of plain carbon steel vary with the heat treatment condition. We prepared six different samples in three different heat treatment configurations and performed hardness tests on them by using the Rockwell tester and observed the microscopic using optical microscope. Based on the optical microscope observation, we found that the crack is appeared at the tempering stage, because the grain size is larger compared at the austenitizing stage at higher tempering temperature. Larger grain
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TTT and CCT diagrams generally contain 3 distinct lines, which represent: Nucleation Line – Beginning of the Phase Transformation Process.
50% Completion of the Phase Transformation.
~100% Completion of the Phase Transformation.
Iron – Iron Carbide (steel) TTT and CCT diagrams involve the transformation of Austenite. Looking specifically at eutectoid composition steel (0.77wt% C).

Pearlite is composed of alternating layers of Ferrite and Cementite. Pearlite layer thickness is a function of quenching temperature (and Rate):
1. Thick layers (Coarse Pearlite) are produced at a quench temperature of ~6500
2. Thin layers (Fine Pearlite) are produced at a quench temperature of ~5000
3. A particulate structure (Bainite) is produced at a quench temperature of ~3500

Coarse Pearlite is relatively soft and ductile but is often utilized as a low-cost structural material. Its' properties depend largely on carbon content. Fine Pearlite is generally a mid-range steel with good strength and ductility characteristics; actual properties are a function of carbon content. Bainite is stronger and slightly less ductile than Fine Pearlite. Overall Bainite is a relatively cheap steel which combines good strength with moderate ductility. If Austenite is quenched (cooled rapidly) at a rate such that the knee of the TTT/CCT diagram is avoided (rapid

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