1.
Decreasing grain size in a polycrystalline material
Correct Answer
A. Increases yield strength and corrosion resistance
Explanation
When the grain size in a polycrystalline material decreases, it leads to an increase in both yield strength and corrosion resistance. This is because smaller grain sizes result in more grain boundaries, which act as barriers to dislocation movement and make it more difficult for deformation to occur. As a result, the material becomes stronger and less prone to yielding under stress. Additionally, the increased number of grain boundaries also impedes the movement of corrosive agents, reducing the material's susceptibility to corrosion.
2.
The blade of powder saw is made of
Correct Answer
B. High speed steel
Explanation
High speed steel is the correct answer because it is a type of tool steel that is specifically designed for high-speed applications such as cutting, drilling, and machining. It has excellent hardness, wear resistance, and heat resistance properties, making it ideal for use in cutting tools like saw blades. Boron steel, stainless steel, and malleable cast iron are not typically used for saw blades due to their different properties and characteristics.
3.
Quartz is the types of material
Correct Answer
C. Piezo electric material
Explanation
Quartz is classified as a piezo electric material because it exhibits the piezoelectric effect, which means it can generate an electric charge in response to mechanical stress or pressure. This property makes quartz widely used in various applications, such as in electronic devices, sensors, and watches, where its ability to convert mechanical energy into electrical energy is utilized.
4.
In low carbon steel, presence of small quantities of sulpher improves.
Correct Answer
C. Machinability
Explanation
The presence of small quantities of sulfur in low carbon steel improves its machinability. Sulfur acts as a lubricant during the machining process, reducing friction and heat generation. This helps in achieving smoother and faster cutting, resulting in improved machinability.
5.
Babbit lining is used on brass/bronze bearing to.
Correct Answer
D. Increase wear resistance
Explanation
Babbit lining is used on brass/bronze bearings to increase wear resistance. Babbit lining is a type of material that is softer than the brass/bronze bearing itself. By applying a layer of Babbit lining on the bearing surface, it creates a sacrificial layer that can wear away over time instead of the bearing material. This helps to prevent direct contact between the bearing and the rotating shaft, reducing friction and minimizing wear on the bearing itself. Therefore, the use of Babbit lining increases the wear resistance of the brass/bronze bearing.
6.
Euteactoid reaction occurs at.
Correct Answer
B. 723 centigrade
Explanation
The eutectoid reaction occurs at 723 degrees Celsius. This is the temperature at which a solid phase transforms into two different solid phases. It is a specific type of phase transformation that happens in certain alloys, such as steel. At this temperature, the eutectoid composition undergoes a transformation from austenite to pearlite. This reaction is important in the heat treatment of steel, as it affects its mechanical properties.
7.
Type question here
Correct Answer
A. Answer option 1