Engineering Materials MCQ Questions & Answers | Mechanical Engineering

Most of the world's steel is produced by the electric-arc method, which uses high-current electric arcs to melt steel scrap and convert it into liquid steel of specified chemical composition and temperature.
This process is adapted to Alloy and carbon tool steel and Magnet steel and High speed tool steel

The correct answer is Option B: Refines grain size and produces less tendency to carburisation, improves corrosion and heat resistant properties
Here's why:
Chromium is a very important element added to steel to change its properties.
Option A is incorrect because while chromium does improve wear resistance, it doesn't significantly improve cutting ability and toughness on its own. Other elements are more important for those properties.
Option B is correct. Chromium significantly improves the steel's ability to resist corrosion (rust) and oxidation at high temperatures (heat resistance). It also helps in refining the grain size of the steel, making it stronger and tougher. Finally, it reduces the tendency for the steel to absorb carbon during heat treatment (carburization).
Option C is incorrect because chromium typically *increases* hardenability, not reduces it. And it does not mainly improve cutting ability.
Option D is partially correct, it mentions anti-corrosion properties, which is true for chromium. However, chromium alone does not primarily give ductility or toughness in steel. Other elements, like nickel, are more important for that. Also, while it contributes to tensile strength, it's not the main element responsible. So, Option D is not the *best* answer.
Therefore, Option B most accurately describes the primary effects of chromium in steel.

Cold chisels are made from carbon tool-steel, which is usually octagonal in cross-section.
Tool-steel is used as it can be hardened to form a hard and tough cutting edge.
To make a cold chisel heat the end of the bar of tool steel until it is bright red and hammer to the desired shape.

Cast iron is a ferrous alloy which has more than 2% carbon in it.
Though it can have any percentage of carbon between 2% to 6.67%, but practically it is in between 2% to 4% only.

Eutectoid steel contains 0.8% of carbon

Cast iron is brittle, hard, and non-malleable.
It can't be bent, stretched, or hammered into shape.
Its weak tensile strength means that it will fracture before it bends or distorts.

cast iron properties are listed below:
It has three to five times more compression strength compared to steel
It has Good machinability (gray cast iron)
It has excellent anti-vibration (or damping) properties hence it is used to make machine frames
It has good Sensibility
It has excellent resistance to wear
It has constant Mechanical properties between 20 to 350 degree Celsius
It has very low notch sensitivity
It has Low stress concentration
It bears Low cost
It is Durability
It has Resistance to deformation

Most-common type of steel that contains about 0.1 to 0.3 percent carbon.
In general, increase in the amount of carbon reduces ductility but increases tensile strength and the ability to harden through tempering.
As an industry-wide practice, steel that does not contain any specified or standard amount of one or more alloying elements (such as chromium, molybdenum, nickel, titanium, vanadium) to be classified as alloy steel is called carbon steel

High carbon steel carries carbon percentage of 0.8 to 1.5%

Carbon steel - carbon range 0.35 to 0.45%
40c8 actually gives you the carbon and manganese value in the steel.
this designation is mostly used for plain carbon steels.
It's a percentage of Carbon (letter C) in the steel.