Alloy Phase Diagram Computation and Analysis

Week 4 Mentor session Sicong He (Alan) • Assignment 3 • Assignment 4 • Coding Assignment 3: Alloy phase diagram computation with Thermocalc • Go to https://thermocalc.com/academia/ and download the Thermocalc free educational package and install it on your computer. • Watch the following videos prior to doing the assignment: • Introduction to the software: https://www.youtube.com/watch?v=l71YtWromGA • Guide to determine alloy phase diagrams: https://www.youtube.com/watch?v=3_56pWJY1-c • Example phase diagram for the Fe-C system: https://www.youtube.com/watch?v=ibsL71cTcMM • Work on the determination of the phase diagrams of two binary alloys. • Start with one with full solubility (e.g., Au-Ag, or W-Ta) and then study one one displays intermetallic phases (e.g., Cu-Zn, Fe-Cr). • Write a brief report based on your results and experience using the software. Au-Ag binary alloy system, use the ‘PURE5’ thermodynamic database Fe-Cr binary system, use the ‘FEDEMO’ database 1. The phase diagram for iron-iron carbide (Fe – Fe3C) is shown below. For a 0.95% C steel (i.e. 1095 series) at a temperature just below the eutectoid temperature (727◦C) determine: (a) % C present in the ferrite (α). (b) % C present in the cementite (Fe3C). (c) total % of the steel that is ferrite (α). (d) total % of the steel that is cementite (Fe3C). (e) % of steel that is pearlite. (f) % of steel that is proeutectoid ferrite. (g) % of steel that is eutectoid ferrite. (h) % of steel that is proeutectoid cementite. (i) % of steel that is eutectoid cementite. (j) Compare this material qualitatively with steel with the eutectoid composition of 0.8%C (assuming similar thermal history) in terms of: i. Cementite content ii. Strength (σY and σU T S ) iii. Ductility iv. Toughness v. Hardness 4. A steel plate is passed through rollers which reduce the thickness from 2 inch to 1 and 15/16 inch in a single pass. What is the % C.W.? Qualitatively describe what happens to the yield strength of the plate as a result and show this using a sketch of the σ − ε curve before and after rolling. 5. An aluminum rod of Diameter D = 2 in is extruded into the T-slotted below. What is the % C.W. if the final profile area is A = 1.216 in2. 6. Label the Eutectoid steel TTT diagram below to show: (a) Regions where the stable phase is: i. Austenite ii. Coarse Pearlite (α + Fe3C) iii. Fine Pearlite (α + Fe3C) iv. Upper Bainite v. Lower Bainite vi. Martensite (b) Cooling curves that result in: i. 100% Coarse Pearlite ii. 50% Fine Pearlite + 50% Martinsite iii. 100% Martinsite (For each case, label the quencing medium (or media) used to obtain the final microstructure)