Reference no: EM132352554

Problem 1 :

Consider a high density, semi-crystalline thermoplastic polymer containing both amorphous and crystalline phases. Discuss the relationship between strain rate sensitivity, viscoelasticity and percent crystallinity in this type of polymer, and indicate how deformation occurring in the microstructure influences this relationship.

Hint: you may want to consider using semi-crystalline polymer tensile specimens subject to an increasing force applied at different strain rates in your explanation. How does a high percent crystallinity vs. low percent crystallinity tensile specimen compare in terms of what the microstructure looks like, and how each tensile specimen responds to increasing strain rates?

Problem 2 :

Austenitized low carbon steel that is rapidly quenching to room temperature generally forms 100% martensite. In processes involving slower cooling in which unstressed, equiaxed pearlitic and ferritic grains form, the grain crystal structure takes on a BCC crystal structure morphology, while the martensitic grains often form a BCT arrangement.

a) Represent the family of planes and directions associated with dislocation motion for both the pearlitic BCC and martensitic BCT crystal structures using miller indices.

b) Explain why martensite is generally higher in strength, lower in ductility, and exhibits greater anisotropy than unstressed pearlitic and ferritic microstructures.

Attachment:- Final Exam-cylindrical pressure vessel.rar