This Educational blog provides questions and answer and important mcq points for all competitive exams like UPSC, GPSC, GSSSB, SSC, CGL, JE, SE, NDA, PSC, GATE, Bank, RAILWAY, JEE, All India PSC Exam, and other Government exam body.
Annealing is a heat treatment process which alters the microstructure of a material to change its mechanical or electrical properties. Typically, in steels, annealing is used to reduce hardness, increase ductility and help eliminate internal stresses.
43.Steel containing up to 0.15% carbon, is known as
Dead Mild Steel has a carbon content of between 0.05% and 0.15%. This gives Dead Mild Steel the property of good Ductility and the ability to be easily formed. Some of the uses of Dead Mild Steel are : Tinplate, Car Bodies, Chains, Nails, Thin Wire, etc.
Gunmetal, also called G Metal, variety of bronze, formerly used for ordnance. Modern admiralty gunmetal is composed of 88 percent copper, 10 percent tin, and 2 percent zinc and is used for gears and bearings that are to be subjected to heavy loads and low speeds.
33.The percentage of phosphorus is phosphor bronze is
Malleable iron is cast as white iron, the structure being a metastable carbide in a pearlitic matrix. Through an annealing heat treatment, the brittle structure as first cast is transformed into the malleable form.
Chilled cast iron. Iron-carbon alloy with low graphitization factor so that chill occurs forming a graphite-free structure. The carbon is present bonded in the form of iron carbide, which is why the break surface of the material appears whitish instead of gray.
36.The red flame during the operation of a bessemer converter indicates that the
red flame does not occur during the operation of a Bessemer converter.
Note:- Bessemer converter is a steel-making process, now largely superseded, in which carbon, silicon, and other impurities are removed from molten pig iron by oxidation in a blast of air in a special tilting retort (a Bessemer converter ).
Phosphor bronze is an alloy of copper with 0.5–11% of tin and 0.01–0.35% phosphorus. The tin increases the corrosion resistance and strength of the alloy. These alloys are notable for their toughness, strength, low coefficient of friction, and fine grain.
38.In the austempering process of heat treatment, austenite changes into
Austempering is a heat treating process for medium-to-high carbon ferrous metals which produces a metallurgical structure called bainite. It is used to increase strength, toughness, and reduce distortion.
39.Which of the following material has maximum malleability?
Lead is a chemical element with symbol Pb and atomic number 82. It is a heavy metal that is denser than most common materials. Lead is soft and malleable, and has a relatively low melting point.
Melting point: 327.5 °C.
Boiling point: 1,749 °C.
40.The machine tool guide ways are usually hardened by
Heat is applied to the part being hardened, using an oxy- acetylene (or similar gas) flame on the surface of the steel being hardened and heating the surface above the upper critical temperature before quenching the steel in a spray of water. The result is a hard surface layer ranging from 0.050" to 0.250" deep.
Hematite, also spelled as hematite, is the mineral form of iron(III) oxide, one of several iron oxides. It is the oldest known iron oxide mineral and is widespread in rocks and soils.
Mohs scale hardness: 5.5–6.5.
25.A carbon steel having Brinell hardness number 100 should have ultimate tensile strength closer to
BHN is designated by the most commonly used test standards (ASTM E10-14 and ISO 6506–1:2005) as HBW (H from hardness, B from Brinell and W from the material of the indenter, tungsten (wolfram) carbide). In former standards HB or HBS were used to refer to measurements made with steel indenters.
26.The steel widely used for making precision measuring instruments is
High Speed Steels are high-performance special steels offering high hardness at temperatures up to 500°C and high wear resistance, thanks to alloying elements like tungsten, molybdenum, vanadium and chromium which are able to form carbides. To improve hot hardness, cobalt may also be added.
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally pig iron, but also others such as lead or copper. Blast refers to the combustion air being "forced" or supplied above atmospheric pressure.
