Engineering Stress-Strain Curve The engineering stress-strain curve gives the relationship between stress and strain for a ductile material. It is generally obtained by applying load to a tensile specimen. The curve reveal many properties of a material such as Young's Modulus(E), Yield point, UTS   etc. Stress : The stress in the engineering stress-strain diagram is given by load divided by the original area. Strain : The strain in the engineering stress-strain curve is giver by ratio of change in length / elongation to its initial length. Strain has no unit since it’s a ratio of two quantities. Proportionality limit : I...

                                                                    THE ELLINGHAM DIAGRAM The Ellingham diagram is the simplest method of representing the relationship between the free energy( Δ G) and temperature of various oxides and sulphides. In metallurgy, the Ellingham diagram is used to   find out a suitable reducing agent. In the Ellingham diagram the highly stable oxides are found at the bottom and the less stable oxides are found at the top. An element occupying a lower position in the diagram can reduce the oxides of another element present above it. For example, Mg lies below Si thus Mg can be used as a reducing agent for oxides of Si. Why Ellingham diagram has all straight lines? Reason for upward slope of line...

THE IRON-CARBON PHASE DIAGRAM Of all binary alloy systems the one that is possibly the most important for a metallurgist is the iron and carbon system. We know that both steel and cast iron play a important role in structural applications and they both are iron-carbon system. Pure iron upon heating experiences changes in its crystal structure until 1538 °C and melts there. At room temperature it is present at a stable form called ferrite(α), which has a BCC crystal structure. The ferrite transforms to austenite( ט ) at 912°C which has a FCC crystal structure. At 1394°C it again undergoes a phase transformation to                                δ-ferrite which has a BCC crystal structure. Pure iron finally melts at 1538°C. All these changes can be seen in the left vertical axis of the Fe-C phase diagram. In the composition axis ...