Student ID: 17. How does temper embritiement typically affect the material's hardness and tensile properties? b) It Nignificantly decreases both properties. c) It significantly increases both properties. c) It shows no significant change in hardness and tensile properties. d) It reduces both properties at room temperature. 18. What type of stress should be reduced to avoid fracture due to hydrogen embrittiement? a) Compressive stress only c) Tensile stress only b) Residual and applied stress d) Shear stress 19. What is the main effect of hydrogen embrittlement on metals? a) Increased strength b) Reduced ductility c) Improved corrosion resistance d) Increased thermal conductivity 20. How can the occurrence of temper embrittlement be determined? A) Measuring the tensile strength of the material B) Measuring the change in ductile to brittle transition temperature C) Performing a hardness test D) Conducting a fatigue analysis Fall 2024 Time: 30 min

17. How does temper embrittlement typically affect the material's hardness and tensile properties?<br />b) It significantly decreases both properties.<br /><br />Temper embrittlement is a phenomenon that occurs in certain steels and other materials when they are tempered at high temperatures for extended periods. This process can lead to a significant decrease in both the hardness and tensile properties of the material. The material becomes more brittle and less able to withstand deformation or stress.<br /><br />18. What type of stress should be reduced to avoid fracture due to hydrogen embrittlement?<br />b) Residual and applied stress<br /><br />Hydrogen embrittlement is a phenomenon where the presence of hydrogen in a material makes it more susceptible to fracture under stress. To avoid fracture due to hydrogen embrittlement, it is important to reduce both residual and applied stress in the material. Residual stress is the stress that remains in a material after it has been manufactured or processed, while applied stress is the stress that is applied to the material during its use.<br /><br />19. What is the main effect of hydrogen embrittlement on metals?<br />b) Reduced ductility<br /><br />Hydrogen embrittlement is a phenomenon where the presence of hydrogen in a material makes it more susceptible to fracture under stress. The main effect of hydrogen embrittlement on metals is reduced ductility, which is the ability of a material to deform without breaking. When a material is susceptible to hydrogen embrittlement, it becomes more brittle and less able to withstand deformation or stress.<br /><br />20. How can the occurrence of temper embrittlement be determined?<br />B) Measuring the change in ductile to brittle transition temperature<br /><br />The occurrence of temper embrittlement can be determined by measuring the change in the ductile to brittle transition temperature (DBTT). The DBTT is the temperature at which a material transitions from a ductile behavior to a brittle behavior. When temper embrittlement occurs, the DBTT increases, indicating that the material becomes more brittle at higher temperatures. By measuring the change in DBTT, it is possible to determine whether temper embrittlement has occurred.