Hardenability - Material Science and Engineering - Exam, Exams of Material Engineering

Download Hardenability - Material Science and Engineering - Exam and more Exams Material Engineering in PDF only on Docsity! Page 1 of 3 CORK INSTITUTE OF TECHNOLOGY INSTITIÚID TEICNEOLAÍOCHTA CHORCAÍ Semester 2 Examinations 2008/09 Module Title: Material Science Module Code: MECH 6025 School: Mechanical & Process Engineering Programme Title: Bachelor of Engineering in Mechanical Engineering – Stage 2 Bachelor of Engineering in Biomedical Engineering – Stage 2 Programme Code: EBIME_7_Y2, EMECH_7_Y2 External Examiner(s): Mr. Murtagh Murphy, Dr. Garrett McGuinness, Mr. Alan Bateman, Dr. Patrick Delassus. Internal Examiner(s): Ms. Sally Bryan Instructions: Answer any 3 questions Duration: 2 Hours Sitting: Summer 2009 Requirements for this examination: Note to Candidates: Please check the Programme Title and the Module Title to ensure that you are attempting the correct examination. If in doubt please contact an Invigilator. Page 2 of 3 Q1. (a) Describe the process of case hardening. Give an example of the application of case hardening and state why it is suitable for that application. (7 Marks) (b) Briefly explain why quenching increases the hardness of a steel. (4 Marks) (c) Define the ‘critical cooling rate’ in the context of quenching. (4 Marks) (d) The Jominy End Test is used to test the hardenability of a steel (i) What does hardenability mean? (4 Marks) (ii) Draw a graph (distance versus hardness) showing the typical results of a Jominy End Test comparing two metals. Label the one with the best hardenability. (8 Marks) (iii) Discuss how the hardenability of a steel be improved? (6 Marks) Q2. (a) How is a composite material different from an alloy? (5 Marks) (b) Describe how lamination increases the tensile strength of a material. (6 Marks) (c) A continuous and aligned glass fibre-reinforced composite consists of 40vol% volume of glass fibres having a modulus of elasticity of 69GPa and 60vol% of a polyester resin that, when hardened, displays a modulus of elasticity of 3.4GPa. (22 Marks) (i) Compute the modulus of elasticity of this composite in the longitudinal direction. (ii) If the cross-sectional area is 250mm2 and a stress of 50 MPa is applied in the longitudinal direction, compute the magnitude of the load carried by each the fibre and matrix phases. (iii) Determine the strain that is sustained by each phase when the stress in part (ii) is applied.