ME 370 Quiz 1 2023 with verified questions and answers

Standard a set of specifications for parts, materials or processes intended to achieve uniformity, efficiency, and a specified quality purpose of a standard limit the multitude of variations that can arise from the arbitrary creation of a part, material or process. Code a set of specifications for the theanalysis, design, manufacture, and construction of something. purpose of a code to achieve a specified degree of safety, efficiency, and performance or quality. physical properties density, color, transparency, conductivity, specific heat, etc. common means of distinguishing different materials mechanical properties modulus of elasticity, yield strength, ductility, toughness, hardness, fatigue, etc. describe how a material responds to a load standard tensile test load and deflection are recorded used to obtain material characteristics and strength (yield strength, ultimate strength, modulus of elasticity, ductility, resilience, and toughness) ductile material will see necking and then fracture brittle material is just fracture yield strength the point at which a material begins to deform permanently (plastic deformation) ultimate stress max stress on the stress strain diagram compression compression tests are used to obtain compressive strengths buckling and bulging can be problematic ductile materials: compression and tension strengths are normally equal brittle material: compression strength is greater than tension strengths torsional strength found by twisting circular bars torsional yield strength max shear stress at the point where the torque-twist diagram becomes significantly nonlinear modulus of rupture torque at max point on torque twist diagram ductility amount of plastic deformation before failure brittle means lack of ductility not lack of strength measure by percent elongation toughness work per unit volume required to fracture a material staring hardening (cold work) process of plastic straining below recrystallization temperature in the plastic region of the stress strain diagram increase yield strength, hardness, and ultimate strength decrease in ductility hardness resistance of a material to penetration by a pointed tool Rockwell and brinell measures the strength temperature effects as temperature increases ductility increases as temperature increases Sut increase than decrease and Sy decreases creep continuous deformation under load for long periods of time at elevated temperatures Stage 1: elastic and plastic deformation, decreasing creep rate due to strain hardening Stage 2: constant minimum creep rate due to the annealing effect Stage 3: increased true stress, increased creep rate leading to fracture resilience capacity of a material to absorb energy within its elastic range metals metallic bonds high thermal and electrical conductivity crystalline structure (BCC, FCC, or HCP) ceramics ionic or covalent bonds high hardness, stiffness, and brittleness polymers secondary bonds glassy and or crystalline elastic deformation recoverable small atomic movement, no breaking of atomic bonds plastic deformation breaking and reestablishing atomic bonds slip: slip plane and direction twinning: HCP diffusion: high temperatures carbon steels alloys of carbon and iron thermoplastic Capable of being softened by heat; may be remolded. thermoset a plastic for which the polymerization process is finished in a hot molding press where the plastic is liquified under pressure composite materials formed from two or more dissimilar materials, each of which contributes to the final properties specific modulus ratio of young modulus to density specific strength ratio of strength to density Strengthening mechanisms material is strengthened by increasing the resistance to dislocation movement (creating barriers) Strain hardening, grain size refinement, solid solution strengthening, precipitation hardening, and phase transformation heat treatment heating and cooling procedure to manipulate structural changes (affect materials properties) for metals mostly Annealing heating the metal to a high enough temperature for a certain time and cooling slowly form equilibrium recrystallized structures to soften metal for improved machinability and formability Quenching and Temping cooling rapidly to form very hard and brittle material tempered martensite (reduce brittleness) Quenching and aging cooling rapidly to form oversaturated non-equilibrium structure form fine precipitates from aging (precipitation hardening) Solidification Process starting material is heated sufficiently to transform it into a liquid or highly plastic state molding for plastics particulate processing starting material consists of powders pressing to enhance formability sintering deformation processing starting work part is shaped by application of forces that exceed the yield strength of the material forging, extrusion material removal process excess material is removed from the starting work piece so what remains is the desired geometry turning, drilling, milling quenching controlled cooling rate prevents full annealing increased strength, hardness, and brittleness tempering reheat after quenching to a temperature below the critical temperature relieves internal stresses increases ductility, slight reduction in strength and hardness hot working process metal is formed while heated above recrystallization temperature refine grain size rough surface finish case hardening process to increase the hardness on outer surface, while retaining ductility and toughness in the core addition of carbon to outer surface