Question

01 Figure Q1 illustrates four micrographs (A, B, C, and D) taken using a scanning electron microscope. For each micrograph: Draw a sketch outlining the main features. (2 marks) (ii) Identify the microstructure explaining your decision. (1 mark) (iii) Explain in detail with the aid of illustrated sketches and graphs how these microstructures (6 marks) were formed. Where possible justify your answer for and against (iv) Comment on the mechanical or environmental properties or an improvement strategy. (1 mark) (Each micrograph: 10 marks: total 40 marks) Micrograph QIA Mag, 180X Micrograph Q1B Mag, 500x 12:19 000007 D 3.4m 25.01 1.52 20 jorui Micrograph QIC Mag, 1,500x Micrograph QID Mag. 2,000X Cross-section

Answer 1

The answers for the last 3 sub questions are provided in the following 4 images.

Answer page no-1 Fatique 1:16) Miconograph QIA represents Fracture which shows striations. Micrograph Q2B represents ductile Fracture which also shows void Caalescence & shear. Monograph Qic represents brittle fracture showing grawlar & grains which appear bright Failure Minograph QID represents Greep it sliding. shows boundary grain and OD Fatigue Fracture Microscopic Surface defect Fatique Crack growth Rapid Fracture Fatique Fracture is Caused by the Crack initiation at the surface of a specimen

(Pg No: 2 gradually it grows into the speamen Forwing Some sort of striations. If the distance between those striation is high then it is Cycle fatigue & if is low Called high Fatique low cycle ductile Fracture > س) 4 J Vold growth Vood Joins to Vold nucleation necking form Crack in the on the is It forms by void Coalescene as shown load which figure above it depends applied continuously. As the void gets together and finally collapsed whenever they reached their critical level The Microstowcture appearance dullana Fibrous of grains. is

PgNo: 3 Brittle Fracture is Failure Shape of Brittle Original speamen Fracture * It occurs by cleavage when there is no sufficient plastic deformation, it's mostly observed HCP metal structures, the appearance of Microstowcture granular & bright of grains. Creep perood of KOL Primary creep (2 period of 2 Crep I initial extension period of 3 creep Time It occurs by sliding of the grain boundaries only when it happens & there are high angle boundaries because they Tast. extension of test preu tend to move Very