action: Practice for Exam https://vie.exeter.ac.uk/pluginfile.php/3 Question 2 AISI 4340 steel can be quenched and tempe

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Action Practice For Exam Https Vie Exeter Ac Uk Pluginfile Php 3 Question 2 Aisi 4340 Steel Can Be Quenched And Tempe 1 (52.9 KiB) Viewed 22 times

action: Practice for Exam https://vie.exeter.ac.uk/pluginfile.php/3 Question 2 AISI 4340 steel can be quenched and tempered to improve its fracture toughness, but in this process sacrifices its yielding strength. A relation between fracture toughness and yielding strength of AISI 4340 steel is shown in Figure Q2 below. Ke= 187 MPa√m and = 760 MPa. di 150 200 250 300 200100 AISI 4340 Steel 800 2000 1200 1000 de Yield Strength, MPa Figure Q2: Fracture toughness vs. yield strength for AISI 4340 steel at various strength levels. (a) Obtain approximate values of fracture toughness K, for AISI 4340 steel that has been heat-treated to yield strengths of 1000 and 1600MPa. i. Calculate the transition crack length at these two strengths. Comment on its significance on design criterion considerations. (b) A spherical pressure vessel is made of AISI 4340 steel with a yielding strength of 1000 MPa. Its inner diameter is 1.5 m and its wall thickness is 10 mm. If the vessel is to be operated at a room temperature of 25 "C and a maximum pressure of 8 MPa, is the design fit for leak-before-break condition? Ensure that you explain your reasoning. (c) A crack-induced leak is found in the vessel. i. What is the stress intensity factor when the leak occurs? . What are the safety factors against brittle fracture and yielding in this case? ii. Comment on their significance in design consideration. You may assume the aspect ratio of the crack remains the same regardless of its size Kie Fracture Toughness, MPa/m 100 120 80 40 160 120 80 40 0 KK ksi/in