Lecture #3 HW

pdf

School

New Jersey Institute Of Technology *

*We aren’t endorsed by this school

Course

215

Subject

Mechanical Engineering

Date

Jan 9, 2024

Type

pdf

Pages

Uploaded by JusticeSquirrel3806

Lecture #3 HW – Chapter 2 - 3) Knowledge of what four aspects and their interrelations is critical to the successful application of a material in an engineering design? - Knowledge of structure, properties, processing, and performance are the four aspects critical to the successful application of a material in an engineering design. 6) What are some properties commonly associated with metallic materials? - Wood, brick, concrete, and plastic are properties commonly associated with metallic materials. 10) What are the standard units used to report stress and strain in the English system? In the metric or SI system? - The standard unit to report stress is in psi and MPa. The standard unit to report strain is in/in, mm/m, and %. 11) What are static properties? - Static properties are a standard number established by tests under static loads. 15) What are some of the tensile test properties that are used to describe or define the elastic-to-plastic transition in a material? - Young's modulus, modulus of resilience, plastic deformation, yield point, and ductility are some of the tensile test properties that are used to define the elastic-to-plastic transition in a material. 16) Why is it important to specify the “offset” when providing yield strength data? - It’s important to specify the “offset” when providing yield strength data as it defines the amount of stress required to produce the permissible strain. 21) What are two tensile test properties that can be used to describe the ductility of a material? - Percent and uniform elongation are two tensile tests that can be used to describe the ductility of a material. 24) What is the toughness of a material, and how might the tensile test provide insight? - Toughness of a material is the work per unit volume required to fracture the material. Tensile test provides insight for the strength and ductility of the material. 42) Describe several types of dynamic loading. - Types of dynamic loading include, wind hitting the side of a structure, car driving across a bridge, earthquakes. 43) Why should the results of standardized dynamic tests be applied with considerable caution? - Results of standardized dynamic tests should be applied with considerable caution as they can have limitations as conditions tent to vary.

Chapter 4 – 2) What are some features that are useful in defining a phase? - Useful features in defining a phase include definable structures, composition, and interfaces. 4) What is an equilibrium phase diagram? - An equilibrium phase diagram is a graphical mapping of the tendencies of a material or a material system. 12) What is a solubility limit, and how might it be determined? - The solubility limit is the maximum amount of solute that can dissolve. It can be determined by mass or solute/volume. 13) Describe the conditions of complete solubility, partial solubility, and insolubility. - Complete solubility is when two materials are completely soluble. Partial solubility is when two materials are soluble to each other to a limit or saturation point. Insolubility is when one or both materials are totally insoluble with the other. 14) What types of changes occur upon cooling through a liquidus line? A solidus line? A solvus line? - The change occurs through a liquidus line is two materials forming a uniform liquid solution. A solidus line is uniformly distributed single-crystalline lattice solid. Solvus is a mixture of two phases. 15) What three pieces of information can be obtained for each point in an equilibrium phase diagram? - Temperature, pressure, and composition are information that can be obtained for each point in an equilibrium phase diagram. 16) What is a tie-line? For what types of phase diagram regions would it be useful? - A tie line is an isothermal line drawn through the point of consideration of phase boundary on each side. It’s useful for determining the composition of phases. 17) What points on a tie-line are used to determine the chemistry (or composition) of the component phases? - The intersection between the tie-line and the liquidus shows the composition of the liquid phase, and the intersection between the tie-line and the solidus shows the composition of the solid phase. 18) What tool can be used to compute the relative amounts of the component phases in a two-phase mixture? How does this tool work? - The tie-line can be used to make lever-law calculations. (α-S₂)/(L₂-S₂)×100%. 22) What is the general form of a eutectic reaction? - L -> S1 + S2

28) In what form(s) might intermetallic compounds be undesirable in an engineering material? In what form(s) might they be attractive? - Intermetallic compounds are undesirable when in large quantities along with grain boundaries. They are attractive when dispersed throughout small particles. 29) What are the four single phases in the iron–iron carbide diagram? Provide both the phase diagram notation and the assigned name. - The four single phases in the iron-iron carbide diagram are delta-ferrite (BCC), austenite (FCC), ferrite (BCC), cementite (Fe3C) 30) What features of austenite make it attractive for forming operations? What features make it attractive as a starting structure for many heat treatments? - Having low strength, high ductility, and chemical uniformity are features that make austenite attractive. 32) Which of the three-phase reactions in the iron–carbon diagram is most important in understanding the behavior of steels? Write this reaction in terms of the interacting phases and their composition. - Conversion of austenite to the two phases ferrite and carbide are the most important to understanding behaviors of steels. (.77%C, FCC)= Ferrite (.02%C, BCC)+ Cementite (6.67%C) 33) Describe the relative ability of iron to dissolve carbon in solution when in the form of austenite (the elevated temperature phase) and when in the form of ferrite at room temperature. - When the iron conversion from FCC austenite to BCC ferrite, it rejects the excess carbon and forms cementite. This results in a mixture of ferrite and cementite. 34) What is pearlite? Describe its structure. - Pearline is a mixture of ferrite and cementite in a steel and iron cast. It has a lamellar structure. 35) What is hypoeutectoid steel, and what structure will it assume upon slow cooling? What is a hypereutectoid steel, and how will its structure differ from that of a hypoeutectoid? - A hypoeutectoid steel has less than 0.77% of carbon in its structure. Once slowly cooled, it produces a mixture of a proeutectoid ferrite and pearlite. Its structure differs from hypoeutectoid as it is cementite. 37) In addition to iron and carbon, what other element is present in rather large amounts in cast iron? - Small amounts of manganese, sulfur, and phosphates while it has large amounts of silicon. 39) What are the two possible high-carbon phases in cast irons? What features tend to favor the formation of each? - The two high-carbon phases in cast irons are graphite and cementite. Slow cooling, high carbon, high silicon are features that favor graphite. Fast cooling, low carbon, and thing sections favor cementite.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version