Q1: Increasing the carbon content of steel

ANS:B - increasing the ductility transition temperature.

Increasing the carbon content of steel affects its properties in various ways:

1. Reduces the Upper Shelf Energy: The upper shelf energy refers to the amount of energy absorbed by a material before it fractures in a Charpy impact test. Increasing the carbon content of steel tends to reduce its upper shelf energy, making it more susceptible to brittle fracture, particularly at lower temperatures.
2. Increases the Ductile to Brittle Transition Temperature: Increasing the carbon content of steel can raise its ductile to brittle transition temperature. This transition temperature is the temperature at which the steel changes from ductile (tough and able to deform without fracturing) to brittle (prone to sudden, catastrophic failure without warning).
3. Decreases Brittleness: Contrary to reducing brittleness, increasing the carbon content of steel tends to increase its brittleness, especially at lower temperatures. This is because higher carbon content promotes the formation of brittle microstructures such as martensite.
4. Increases Hardness: Increasing the carbon content of steel generally increases its hardness. This is due to the formation of harder microstructures, such as martensite, which result from the increased carbon concentration. Hardness is a measure of a material's resistance to deformation or scratching.

In summary, increasing the carbon content of steel can lead to reduced upper shelf energy, increased ductile to brittle transition temperature, increased brittleness, and increased hardness, depending on the specific application and the desired properties of the steel.