Using the TTT diagram for eutectoid steel, draw the specified cooling path on the diagram. Indicate what phases you expect in the final product with percentage of each phase. Assume the material has been fully austenitized before cooling. a. Water cool to room temperature b. Hot quench in molten salt to 690°C and then cooled isothermally for 2 hours: c. Hot quench to 610°C hold 3 minutes and water quench

Using the TTT diagram for eutectoid steel, draw the specified cooling path on the diagram. Indicate what phases you expect in the final product with percentage of each phase. Assume the material has been fully austenitized before cooling. a. Water cool to room temperature b. Hot quench in molten salt to 690°C and then cooled isothermally for 2 hours: c. Hot quench to 610°C hold 3 minutes and water quench

Precision Machining Technology (MindTap Course List)

2nd Edition

ISBN:9781285444543

Author:Peter J. Hoffman, Eric S. Hopewell, Brian Janes

Publisher:Peter J. Hoffman, Eric S. Hopewell, Brian Janes

Chapter2: Measurement, Materials, And Safety

Section2.7: Heat Treatment Of Metals

Problem 2RQ: Direct hardening can be performed on steel containing at least________ carbon.

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By using the Iron - Carbon diagram that you have. Find 5 of the following. 1- The microstructure of Cast iron with 3% C. 2- The Liquid and Austinite percent with chemical composition for cast iron with 2% C at 1300°C 3- Find the melting point and microstructure of steel with 0.83% C 4- Define the temperature range for Acm temperature. 5- Find the Ac3, Acl temperature and microstructure of steel with 0.4 % C 6- Find the Eutectic, Eutectoid temperature and microstructure of cast iron with 4.3% C
3.The TTT diagram of a plain carbon steel is given in Fig. 1. Identify whether this steel is a hypoeutectoid, eutectoid or hypereutectoid steel. Explain why the transformation happens slowly at 850°C as well as at 300°C. Determine the microstructures expected in this type of steel after the following heat treatment processes. a) Austenize at 900°C, quench to 400°C and hold for 1000 s and quench to 25°C. b) Austenize at 900°C, quench to 25°C. c) Austenize at 900°C, quench to 675°C and hold for 1 s, quench to 400°C and hold for 900 s and slowly cool to 25°C. 900 Acm Cs 800 A1 FezC + Y 33 Fe3C + pearlite 45 700 Ps 600 ++ Fe3C + pearlite Y+ bainite Bs 500 46 Bainite 400 Yu Bf 300 57 Ms 200 60 Mf Y+ martensite 100 62 Martensite 102 65 103 104 105 106 0.1 1 10 Time (s) Fig. 1 Temperature (°C) Rockwell C hardness
- The microstructure for AISI 1080 carbon steel after heat 760°C then For AISI 1080 carbon steel, heat to 760°C after suitable holding time, cool rapidly to 650°C, hold for 90s, then quench to room temperature. A. 50% martensite 50% perlite B.100% pearlite C. 50% bainite 50% pearlite D. 100% bainite -The microstructure for AISI 1080 carbon steel after heat to 760°C then rapidly cool to 600°C, hold for 4 s, rapidly cool to 450°C, hold for 100 s, then quench to room temperature. A. 50% pearlite, 25% bainite, and 25% martensite B. 50% pearlite 50% bainite C. 25% pearlite, 25% bainite, and 50% martensite D. 50% pearlite, 50% martensite - The microstructure for AISI 1080 carbon steel after heat to 760°C then cool rapidly to 400°C, hold for 15 s, then quench to room temperature A. 100% martensite B. 100% bainite C. 50% bainite 50% martensite D. 25%bainite 75% martensite - The microstructure for AISI 1080 carbon steel after heat to 760°C then rapidly cool to 600°C, hold for 90 s, rapidly cool…
2 By using the Iron - Carbon diagram that you have. Find 5 of the following. 1- Find the Eutectic, Eutectoid temperature of cast iron with 4.3% C 2- The microstructure of Cast iron with 3.5% C. 3- Find the melting point and microstructure of steel with 0.83% C 4- Define the temperature range for Acm temperature. 5- Find the AC3, Ac¡ temperature of steel with 0.45% C 6- The Liquid and Austinite percent with chemical composition for cast iron with 2.3% C at 1300°C
14- On the basis of accompanying isothermal transformation diagram for a 0.45 wt% C iron- carbon alloy, specify the nature of the final microstructure for the following heat treatments after austenitizing the sample at 775°C: a. Rapidly cool to about 590°C (just above the doted line), hold at this temperature for 10 s, and then rapidly quench to room temperature. b. Rapidly cool the specimen to about 675°C, hold at this temperature for 1000 s, then rapidly quench to room temperature. c. Reheat the specimen in part (b) to 700°C (1290°F) for 20 h then slowly cool to room temperature. d. Rapidly cool to about 400°C, hold at this temperature for about 1 s, and then rapidly quench to 295°C and hold for 1000 s then slow cooling. e. Rapidly cool to room temperature then reheat to 425°C for 4000 s then slowly cool to room temperature. Temperature (°C) 900 800 700 600 500 400 300 200 100 0 0.1 A A M(start) M(50%) M(90%) 1 A+ F B 10 A + P A + B *50% 10² Time (s) 10³ 104 1600 1400 1200 1000 800…
2. Please complete the table below. Please fill the name of the phases after the indicated heat treatment. Phases before Cooling speed or heat Phases after heat treatment heat treatment treatment process Pearlite Slow / Anncaling Pearlite Austenite Moderate cooling Austenite Quenching Austenite Quenching + Tempering
Direct hardening can be performed on steel containing at least________ carbon.
1-Compact Graphite cast iron was obtained from fast cooling rates.? T F 2-Strength and ductility of nodular iron approximately the same under tension and compressive loads.? T F 3-The grey should be heated to 700 oC for 30 hours to obtain malleable iron? T F 4-The carbon in CGI alloys is neither flakes nor cementite? T F 5-Exhaust manifold manufactured from white cast iron.? T F 6-The reduced section length of the tensile specimen should be at least four times the diameter.? T F 7-Tangent modulus is taken as the slope of the stress–strain curve at yield stress? T…
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? 800 1400 Ae lemperature Austenite *peorlite begins 10FI 700 1200 Austenitepearlite complete 1600 1000 5009 800 Tronsformation stops 400 600 300 400 Austenite -mortenstic structure 200 -Isathermal dogram Continuous transformaton diogrom Constant rate coding curves - 100 200 Findl structure Mortensite Morlensite i peorlile Peorite (softer, coorser- 0.1 10? 10 Tronsformation time, seconds Continuous Cooling-Transformation (C-T)Diagram (Derived from the isothermal-transformation diagram for a plain-carbon eutectoid steel) 1200 Glass Crystallization begins 1100 1000 Critical cooling rate Glass-ceramic 900 Crystallization ends 800 700 102 10…
The TTT diagram for a 1076 eutectoid steel is given: What is the heat treatment process to form 50% Coarse Pearlite + 50% Martensite. 800 A 1400 Eutectoid temperature 700 A 1200 600 1000 500 800 400 A 600 300 M(start) 200 50% 400 M + A M(50%) M(90%) 100 200 10-1 1 10 102 103 104 105 Time (s) Temperature (°C) Temperature (°F)
Question-6 A 0.25% C hypoeutectoid plain-carbon steel is slowly cooled from 950°C to a temperature just slightly below 723°C. (a) Calculate the weight percent proeutectoid ferrite in the steel. (b) Calculate the weight percent eutectoid ferrite and weight percent eutectoid cementite in the steel.
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