Presents various problems and solutions related to the Metal Materials Function Master practical exam, covering topics such as microscopic structure inspection, ferrite grain size determination method, heat treatment, carburized steel, and stainless steel.
Covers a wide range of metal material knowledge, including BCC packing efficiency, pearlite formation, cold working, mass effect, Gibbs phase rule, hardness comparison, magnetic particle inspection, liquid penetrant inspection, and amorphous alloys.
Summarizes essential content for preparing for the Metal Materials Function Master exam, making it a valuable learning resource for exam success.
1. Write the procedure for metallographic examination of metal materials.. ◑ Specimen sampling - Specimen mounting - Etching - Drying - Microscopic observation
4. Draw a diagram and explain the precipitation mechanism during pearlite formation. ◑ Fe3C nucleation and growth at the austenite grain boundary ◑ Fe3C nucleus growth ◑ Ferrite formation around Fe3C ◑ Fe3C formation at the ferrite grain boundary
5. Write the requirements for carburizing steel. ◑ It should be low carbon steel. ◑ It should not contain elements that hinder carburization. ◑ Grain growth should not occur when heated at high temperatures for a long time. ◑ There should be no porosity or cracks during casting. ◑ It should have good machinability and workability.
6. Write the propane gas combustion reaction in a furnace and the gas ratio (air:propane) in case of complete combustion. ◑ C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(l) ◑ In case of complete combustion, gas ratio → 5:1
7. Write the 3 stages that occur when annealing cold-worked metal and their driving forces. ※ 3-stage phenomenon and driving force ◑ Recovery: Stored energy within the metal ◑ Recrystallization: Strain energy accumulated during cold working ◑ Grain growth: Reduction of grain boundary interfacial energy
8. Write 3 mass effects in heat treatment. ◑ Even with the same type of steel, the hardening depth varies depending on the size (mass) of the product. ◑ Hardness decreases continuously from the surface to the center. ◑ When the mass is large, a rapid decrease in surface hardness occurs.
9. What are the microstructures at positions a, b, c, d, e, f in the quenching-tempering microstructure transformation diagram?
10. What is Gibbs' phase rule? ◑ C variable = Number of substances ◑ P equation = Number of substance phases (gas, liquid, solid) ◑ F degree of freedom = C - P + 2 In this case, the reason for adding 2 is that, in addition to the number of substances and the number of phases, the experimenter can independently change P and T, so 2 is added when calculating the degree of freedom.
11. List the following microstructures in order from highest to lowest hardness. ★ From highest to lowest hardness (cementite-martensite-troostite-sorbite-pearlite-austenite-ferrite) Cementite → Martensite → Troostite → Sorbite → Pearlite → Austenite → Ferrite
☆ From lowest to highest hardness (ferrite-austenite-pearlite-sorbite-troostite-martensite-cementite) Ferrite → Austenite → Pearlite → Sorbite → Troostite → Martensite → Cementite
12. What is the process of removing graphitic carbon accumulated in a carburizing furnace or a carbonitriding furnace by injecting an appropriate amount of air as needed or regularly because it degrades the function of the carburizing furnace or carbonitriding furnace? ◑ Burn-out
13. When a specimen with a carburizing depth (t) as shown in the figure is to be transferred with an inclination to observe a wider surface, that is, twice the area, calculate the angle of inclination.
14. Write 5 purposes of spheroidizing annealing. ◑ Refinement of microstructure ◑ Increase in toughness ◑ Uniformity of quenching ◑ Reduction of quenching distortion ◑ Increase in machinability
15. Write 5 types of magnetic particle inspection magnetization methods. ◑ Yoke method ◑ Coil method ◑ Magnetic flux leakage method ◑ Central conductor method ◑ Prod method
16. Write the process of solvent removable dye penetrant inspection. ◐ Pre-cleaning - Penetrant application - Cleaning - Developer application - Inspection - Drying - Post-cleaning
18. Explain the general properties of amorphous alloys. ◐ Mechanical properties - High toughness, tensile strength, wear resistance, and no crystal defects. - Very good temperature dependence. - Work hardening hardly occurs. - Has high fracture toughness. - Toughness and ductility change significantly with temperature. ◐ Chemical properties - Excellent corrosion resistance.
19. Write 5 pieces of equipment used in radiographic testing.