Below is a continuous cooling transformation curve for steel (upper) and for a silicate melt (lower).Describe the similarities and differences as follows.a. What is the critical cooling rate in each case?b. What phase(s) form in each case when the critical cooling rate is exceeded?c. What phase(s) form in each case if the cooling rate is very slow?8001400Ae lemperatureAustenite*peorlite begins10FI7001200Austenitepearlite complete 160010005009800Tronsformation stops400600300400Austenite -mortenstic structure200-Isathermal dogramContinuous transformatondiogromConstant rate coding curves - 100200Findl structureMortensite Morlensitei peorlilePeorite (softer, coorser-0.110?10Tronsformation time, secondsContinuous Cooling-Transformation (C-T)Diagram(Derived from the isothermal-transformation diagram for a plain-carbon eutectoid steel)1200GlassCrystallizationbegins11001000CriticalcoolingrateGlass-ceramic900Crystallizationends8007001021010101010 1012104Time (s)(logarithmic scale)Temperature, "F250FISTemperature (°C)O 100°C/minTemperature, "C

(a) Critical cooling rates: For steel: critical cooling rate for the steel is the minimum cool rate…

Answered: Below is a continuous cooling…

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

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Part C. Which type of phase transformation is important in heat treatment of steels? (circle one)Peritectic Eutectic Eutectoid Incongruent meltingAt what temperature and overall composition wt% C, does it occur?Write the reaction equation for this transformation, and briefly describe the nature of each of the three important phases that are involved.
1. Why does the tensile strength of steel, which contains only austenite at room temperature, differ fromsteel that shows only pearlite in its microstructure? Give two important reasons for the difference. 2. What general prerequ_isites exist for the formation of martensite in steel? 3. What is an isothermal transformation of a material in the solid state condition? 4. Draw a typical isothermal transformation diagram for plain .carbon eutectoid steel and indicate thevarious decomposition products expected by simple diagrammatic drawing.
Choose one example of an engineering component that is made of steel and requires high hardenability properties. Discuss how the elemental composition of the steel-based material used for your component can be hardened. Your discussion must include the specific composition of the steel, properties, and processing method of the component until it is hardened using a continuous cooling transformation ( CCT ) diagram.
Q.1.For hypoeutoctoid plain carbon steel(select %C content yourself), determine the phasesthat are present, the compositionsof these phases, and the percentages or fractionsof the phases.Make schematic sketches of the microstructurethat would be observed for conditions of very slow cooling at the following temperatures: a)Just above the austenite transformation temperature b)The austenite transformation temperature -10C c)The eutectoid transformation temperature +10C d)The eutectoid transformation temperature -10C
QUESTION 5 Using the continuous-cooling transformation diagram for a eutectoid Fe-C alloy shown below, perform the following tasks. (a) Plot the cooling curve (rough position) corresponding to normalising treatment, and specify the microstructure obtained. (b) Plot the cooling curve (rough position) corresponding to full annealing, and specify the microstructure obtained. (c) Design a heat treatment to produce a duplex microstructure of about half pearlite and half tempered martensite, specifying all the steps and plotting, roughly, the cooling curve involved. (d) If a full (i.e. 100%) tempered martensitic microstructure is desirable, describe the conditions for achieving it in terms of both cooling rate and sample size. (e) What treatment do you propose to do if a fully annealed steel is still too hard for processing (e.g. forging)? Plot the microstructure after such a treatment, marking any dimension that is important.
5. What is the role of austenitic gram size in martensitic transformations? Is austenitic grain size is important to the strength of martensite? What other factors are important to the strength and toughness in technological hardened steels?
Using the isothermal transformation diagram given in Figure 2 for a specific material composition to answer the following (this is NOT an Fe-C steel!). NOTE: Assume that you begin with a single-phase sample of α at 790 C.a. What temperature on the diagram corresponds to the α-to-γ phase transformation temperature that would be found on an equilibrium phase diagram? Explain your answer. b. What temperature would provide the most rapid, isothermal phase transformation of α to γ? What would be the minimum time from onset of the phase transformation to its completion? c. On Figure 2, draw and label a cooling schedule (from 790 C) that will produce a single-phase α material at 100 C. How does the thickness of the piece of material influence your ability to create a single-phase α structure? d. Why does the time to initiate phase transformation become smaller as the temperature is reduced within the temperature range above the “nose” of the TTT diagram? Be specific, what process is…
In a eutectoid steel the following microstructures are required for different application. Suggest cooling rate and sequences to achieve them. a) 50% Pearlite and 50% Bainite b) 50% Bainite and 50% Martensite c)100% fine Pearlite d) 100% Martensite e) 50% Peralite and 50% Martensite
How a heat treatment process needs to be carried out to obtain a martensite structure in steel? answer quickly?
Using the time-temperature-transformation diagram, what steel phases would you generate by cooling from 900ºC A. quenching in cold water to 520ºC in 0.5 second, holding the sample temperature constant for 1000 seconds at 520ºC, and then quenching to room temperature B. cooling down to room temperature over a period of 2 weeks?
1. Given the time-temperature transformation diagram, what would be the phases present for a 1.13 wt. % C steel with no alloying elements. calculate the amount of pro eutectoid product, where applicable (at the bottom) A.) quenched in cold water to 380 C in 0.1 seconds, then held at 380 C for 30 seconds, then quenched to room temperature B.) cooled in air at 2 C/minute to 600oC, then quenched to room temperature C. quenched in cold water to 550 C in 0.1 seconds, then held at 550 C for 2 seconds, then quenched to room temperature D. Necessary Steel Phase Diagram Calculations to determine the amount of pro eutectoid product:
If a 0.80 percent plain carbon steel is austenitized (heated to a read heat) and quenched in water to room temperatures so that the cooling curve does not cut into the “nose” of the I-T diagram, what will the resultant microstructure be?

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