Q1: Austenitized 40 mm diameter 5140 alloy steel bar is quenched in agitated oil. Predict what is theRockwell hardness of this bar will be at (a) its surface and (b) its center (c) What do you think aboutthe difference in hardness number between the center and surface (d) Differentiate between hardnessand hardenability (e) Rank the steels in the figure below from lowest to highest hardenability andexplain why.600-Bar diameter (mm)1008060402003000Cooling rate at 700°C (°C/sec).-150550تنا25-------5S1012.5 8M-RL1/234-RAgitated oil1520¼¾Distance from quenched end. De(Jominy distance)5,554CarBar diameter (in.)025 mm.1 in.Hardness (Rockwell C)Where (C = center, S = surface, M-R = mid-radius)2828 2926560-55-5045403530252015100J1051403020Distance from quenched end (mm)43402 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32Distance from quenched end (sixteenths of an inch)4098404140864050

The hardness is usually based on the hardness of the material.

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Engineering

Mechanical Engineering

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Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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Q1: Austenitized 40 mm diameter 5140 alloy steel bar is quenched in agitated oil. Predict what is the Rockwell hardness of this bar will be at (a) its surface and (b) its center (c) What do you think about the difference in hardness number between the center and surface (d) Differentiate between hardness and hardenability (e) Rank the steels in the figure below from lowest to highest hardenability and explain why. Cooling rate at 700°C (°C/sec) 300 150 011/3 55 100 600 Bar diameter (mm) 80 60 40 20 0 OLL 0 0 ww 25 12.5 8 5 S -------------- M-R 10 3/4-R Agitated oil 15 20 1/4 3/4 Distance from quenched end. De (Jominy distance) 5.5 4 3 Bar diameter (in.) 0 25 mm 1 in. Hardness (Rockwell C) Where (C = center, S = surface, M-R mid-radius) 65 60 55 50 45 40 35 30 25 20 15 10 0 10 1 20 Distance from quenched end (mm) 5140 1 30 L 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 Distance from quenched end (sixteenths of an inch) 4340 40 9840 4140 8640 50
Q4 Answer with True or Fales and re-write the sentence with correction for 10 only 1- Mn Ni Cr, W, Mo, V are the most important elements that forming Austenite. 2- Diamond Pyramid is used for the Scale C in Rockwell hardness test. 3- The stress of forming process must exceed UTS yield point. 4- The brittle transition temperature of steel is within -4 °C to 4°C. 5- Quenching process for steel is used to increase the ductility. 6- The annual quantity production of high production process is more than ten thousand. 7- Knoop test method is used to test the thick and hard material with little load. 8- The purpose of the addition of S to steel with 0.5% is to improve the machinability of steel. 9- The series 4 of Aluminum alloy refer to the presence of Cu as main alloying element. 10- Construction steel with 0.2-0.3% C has higher strength and higher ductility. 11- Austenitic Stainless Steel: contain 16-26 % Cr.
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