Question

Question 2 (20 pts): Charpy V-notch test was performed for different steel specimens. Please answer the following questions briefly. a) (3) As the temperature becomes lower, the metals usually experience a transition from ductile fracture to brittle fracture at a certain temperature. This temperature is called: b) (6) The graph below shows the test results for annealed 1018 steel and annealed 1045 steel. Please label the curves with relevant steel (1018 or 1045) and briefly explain your reason. 1018 AND 1045 Impact Energy (1) 300 250 200 156 100 50 0 -300 -200 100 200 -100 0 TEMPERATURE (°C) c) (4) The appearance of the fractured surface for a material with low Charpy impact energy is: i Dull and fibrous surface ii. Shiny surface Plastically deformed iv. Not deformed, cleavage failure Provide a sketch of the fractured cross-section appearance. d) (4) The appearance of the fractured surface for a material with high Charpy impact energy is: i. Dull and fibrous surface ii. Shiny surface iii. Plastically deformed iv. Not deformed, cleavage failure Provide a sketch of the fractured cross-section appearance. e) (3) If we are selecting a material for a hull of a ship that will operate at temperatures as cold as 0°C, which carbon content would provide the safest steel for our design.

Answer 1

The problem involves the concept of material science and properties of steel . A detailed explanation is given in below images.

temp et abuse experience 'éxinle frochule a which metal usually transitition from ductile to called. Ductile to foittle To ansition Temperature Import Yo A (blue line) Steel 1018 777 B Ched line) Steel 1045 tion Temfelakasle 6 ) Carbon of of 1018 steel = 0.18% 1045 sleel = 0.454 Reason We know as percentage of corbon incle ases fransition from brittle to ductile practure vice verca les shorp. like in B Carbon / of is اع bransition is for low corbon percentage this Shop like more in A () rse When Carbon percentage increase brittleness increa energy of impact reduces And maximum

Page No. : curve Sa Blue line for steel with clow carbon for centage tie. 1018 steel, f red line line is for steel with high carbon percentage in 1045 steel. If Charpy import energy is low then fracture would be brittle know salate_eblained in And we that surf brittle fructure. Il lus turous (shing) Also the crack ampo gates through cleaves & mo_ligifficond deformation occul so answer would be li) Shing surface & CiU) Not Deformed Cleavage failule, Diagrom Begittle foochure surface d) For Charpy impact energy frocure is duchte And for ductile foveture dull & fibrous suffolu is obtained.

Olun Albo plastic deferm ahi so would be they Il Dull & fibrous surface cm2 flash cally deformed onswer playyum Duchte fotture sufou lusually cuff Cone shape shake e Love Carbon content steel would be safest for designing bulls Caxbon bercen tage The reason the reduces the toughness increase & hence Impact energy also increase. Muall seel with Or15 to 0.23% carbon is commonly used In owl case Steel 1018 would be better thon steel 1045 since is of steel 1018 less, coybon percentage

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