MSE_2610_HW_7_solutions

MSE_2610_HW_7_solutions - MSE 2610 Introduction to the...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon
MSE 2610 Introduction to the Mechanical Properties of Materials Fall 2008 Homework Solutions #7 Due: 6 November 2008 1.) Identify the following microstructures: For each, briefly describe: What phase or phases are present? What are the crystal structure(s) of the phases? What approximate ranges of carbon are present in each of the phases? What is a typical morphology for this microstructure (make a sketch). a. Austenite Austenite is a single, high temperature face-centered cubic phase. Austenite can have carbon concentrations from 0% to 2.14%. The phase can exist from 740 o C at the eutectic point (0.65% C) to 1493 o C at the peritectic point (0.16% C) b. Ferrite Ferrite is a single, body-centered cubic phase. Ferrite can have carbon concentrations from 0% to 0.022%. The phase exists at room temperature up to 912 o C for pure iron. c. Pearlite Pearlite is a two- phase, lamellar microstructure of the iron rich ferrite phase and the carbon rich cementite phase. The ferrite phase (as mentioned above) a BCC phase composed of 0.022% carbon. The cementite phase is an orthorhombic crystal with 6.67% carbon. d. Martensite Martensite is a non-equilibrium phase of iron-carbon alloys created by rapidly quenching austenite. It has a tetragonal crystal structure. It can be made from any composition of austenite; however, it becomes impractical at very low carbon concentrations because the required quench rate is too fast.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2.) Answer the following about the equilibrium cooling (cooling sufficiently slowly that the phases present are always as represented on the equilibrium phase diagraram) of austenitic steel: a. What is proeutectoid ferrite? Proeutectoid ferrite is the ferrite that solidifies during cooling through the two- phase region between ferrite and austenite. It solidifies before the eutectoid temperature is reached. b. What is the highest carbon concentration steel can have and still have proeutectoid ferrite upon cooling? The high carbon concentration is the eutectic concentration, 0.65% carbon.
Background image of page 2
Image of page 3
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 12/24/2008 for the course MSE 261 taught by Professor Sass during the Fall '06 term at Cornell.

Page1 / 5

MSE_2610_HW_7_solutions - MSE 2610 Introduction to the...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online