Engineering Materials - Study Mode

[#256] A steel containing 16 to 18% chromium and about 0.12% carbon is called
Correct Answer

(A) Ferritic stainless steel

Explanation

Solution: The correct answer is Option A: Ferritic stainless steel . Let's break down why: Stainless steels are a family of steels known for their corrosion resistance. This resistance comes mainly from the presence of chromium (Cr) . There are different types of stainless steel, and they're classified based on their microstructure (the arrangement of atoms within the metal). * Ferritic stainless steel: * Contains 12 to 30% chromium and a low amount of carbon (typically less than 0.1%) . * They are magnetic and cannot be hardened by heat treatment . * The given composition of 16 to 18% chromium and about 0.12% carbon fits this description. * Austenitic stainless steel: * Contains chromium (typically 16-26%) and nickel (typically 6-22%) . * Nickel is a key element in Austenitic stainless steel which makes them non-magnetic in nature. * They are generally more corrosion resistant and easier to weld than ferritic stainless steels. * The question does not include nickel so it can't be Austenitic stainless steel. * Martensitic stainless steel: * Contains chromium (typically 11.5-18%) and a moderate amount of carbon (typically 0.1-1.2%) . * They can be hardened by heat treatment . * The carbon content in the question is relatively low for a typical martensitic stainless steel. * Nickel steel: * This is a general term for steel alloyed with nickel . * While nickel can improve some properties of steel, it doesn't define the type of stainless steel in this case. Therefore, a steel with 16 to 18% chromium and about 0.12% carbon is most accurately described as Ferritic stainless steel .

[#257] Which of the following is added in low carbon steels to prevent them from becoming porous?
Correct Answer

(D) Silicon

Explanation

Solution: Silicon increases strength and hardness but to a lesser extent than manganese. It is one of the principal deoxidizers used in the making of steels to improve soundness, silicon is detrimental to surface quality, especially in the low carbon, resulphurized grades. It aggravates cracking tendencies when the carbon content is fairly high.

[#258] The correct composition of Babbitt metal is
Correct Answer

(A) 87.75% Sn, 4% Cu, 8% Sb, 0.25% Bi

Explanation

Solution: White metal alloys are those which are light-coloured and generally have a lead or tin base. These alloys are known as Babbitt metal Babbitt metal contains 87.75% Sn, 4% Cu, 8% Sb, 0.25% Bi

[#259] 'Killed steels' are those steels
Correct Answer

(C) Which are deoxidized in the ladle with silicon and aluminium

Explanation

Solution: Killed steels are those steels Which are deoxidized in the ladle with silicon and aluminium

[#260] Tin base white metals are used where the bearings are subjected to
Correct Answer

(A) Large surface wear

Explanation

Solution: Pure metals are soft, tough and ductile with a high coefficient of friction. Intermetallic compounds are hard and wear-resistant but brittle. By themselves, these do not make ideal bearing materials. The white metals are any of several light-colored alloys used as a base for plated silverware, ornaments or novelties, as well as any of several lead-based or tin-based alloys used for things like bearings, jewellery, miniature figures, fusible plugs, some medals and metal type.