QUIZ6-2008key

QUIZ6-2008key - impact energy absorbed versus temperature...

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PRINT NAME ___________________________________ INTRODUCTION TO MATERIAL SCIENCE MSE-150 QUIZ 6 I PLEDGE MY HONOR THAT I HAVE NEITHER GIVEN OR RECEIVED AID ON THIS EXAMINATION. I FURTHER PLEDGE THAT, IF I HAVE REASON TO SUSPECT THAT THE CODE HAS BEEN VIOLATED, I HAVE TAKEN OR WILL TAKE ACTION AS OUTLINED IN THE CODE. SIGNATURE ____________________________________ (1 point each) As the temperature of a material decreases , indicate whether the following mechanical properties increase, decrease, or remains the same. 1- Elastic Modulus increase 2- Yield Stress increase 3- Strain to Failure decrease 4- Impact Energy decrease (1 point each) Match the following types of fracture modes with the descriptions on the right. Creep fracture Deformation at temperature > 0.5 T M Ductile fracture Dimpled rupture and microvoid coalescence Brittle fracture Cleavage or intergranular cracking Fatigue fracture Cyclic loading (1 point each) Circle the types of materials that exhibit a ductile to brittle transition temperature (DBTT) in the
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Unformatted text preview: impact energy absorbed versus temperature diagram. Low Strength BCC metals High Strength alloys Thermoplastics FCC metals (1 point each) Circle the microstructural conditions that decrease the yield strength of a metallic material. Small grain size Low dislocation density Decreasing the percentage of subsitutional alloy elements (1 point) Which materials property is directly related to the yield stress in metals? Critical resolved shear stress Modulus of Elasticity Fracture Toughness (4 points) The fracture toughness of a low-alloy steel (4340) at room temperature is 60.4 MPa √ m. It the material has a surface crack of 1.30 mm in length (a = 1.30 mm), what is the maximum load (N) that a sample with a cross-sectional area of A o =50.0 mm 2 can support before catastrophic failure? (Assume Y = 1.78) K IC = σ Y √π a a) 16.8 b) 531 c) 840 d) 26,500...
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