Tensile strength of steel can be safely increased by
Adding carbon up to 2.8%
Adding carbon up to 6.3%
Adding carbon up to 0.83%
Adding small quantities of copper
Correct Answer :
C. Adding carbon up to 0.83%
Related Questions
Hematite iron ore contains iron about
30 %
45 %
55 %
70 %
The crystal structure of brass is
F.C.C.
B.C.C.
H.C.P.
Orthorhombic crystalline structure
Following elements have face-centred cubic structure
Gamma iron (910° to 1400°C), Cu, Ag, Au, Al, Ni, Pb, Pt
Mg, Zn, Ti, Zr, Br, Cd
A iron (below 910°C and between 1400 to 1539°C), W
All of the above
Which of the following statement is wrong?
Steel with 0.8% carbon is wholly pearlite
The amount of cementite increases with the increase in percentage of carbon in iron
A mechanical mixture of 87% cementite and 13% ferrite is called pearlite
The cementite is identified as round particles in the structure
Recrystallisation temperature is one
At which crystals first start forming from molten metal when it is cooled
At which new spherical crystals first begin to form from the old deformed one when a strained metal is heated
At which change of allotropic form takes place
At which crystals grow bigger in size
The alloy, mainly used for corrosion resistance in stainless steels is
Silicon
Manganese
Carbon
Chromium
Steel with ________ carbon is known as hypo-eutectoid steel.
0.8 %
Below 0.8 %
Above 0.8 %
None of these
Mild steel belongs to the following category
Low carbon steel
Medium carbon steel
High carbon steel
Alloy steel
The defect which takes place due to imperfect packing of atoms during crystallisation is known as
Line defect
Surface defect
Point defect
None of these
Pig iron is the name given to
Raw material for blast furnace
Product of blast furnace made by reduction of iron ore
Iron containing huge quantities of carbon
Iron in molten form in the ladles
Specify the sequence correctly
Grain growth, recrystallisation, stress relief
Stress relief, grain growth, recrystallisation
Stress relief, recrystallisation, grain growth
Grain growth, stress relief, recrystallisation
Which of the following elements does not impart hardness to steel?
Copper
Chromium
Nickel
Silicon
In malleable iron, carbon is present in the form of
Cementite
Free carbon
Flakes
Nodular aggregates of graphite
The metal suitable for bearings subjected to light loads, is
Silicon bronze
White metal
Monel metal
Phosphor bronze
The lower critical temperature
Decreases as the carbon content in steel increases
Increases as the carbon content in steel increases
Is same for all steels
Depends upon the rate of heating
Gun metal contains
70% copper and 30% zinc
90% copper and 10% tin
85 - 92% copper and rest tin with little lead and nickel
70 - 78% copper and rest tin
Preheating is essential in welding
Cast iron
High speed steel
All nonferrous materials
All of the above
An engineer's hammer is made of
Cast iron
Forged steel
Mild steel
High carbon steel
Duralumin contains
94% aluminium, 4% copper and 0.5% Mn, Mg, Si and Fe
92.5% aluminium, 40% copper, 2% nickel, and 1.5% Mg
10% aluminium and 90% copper
90% magnesium and 9% aluminium with some copper
In a hardening process, the hypo-eutectoid steel is
Heated from 30°C to 50°C above the upper critical temperature and then cooled in still air
Heated from 30°C to 50°C above the upper critical temperature and then cooled suddenly in a suitable cooling medium
Heated from 30°C to 50°C above the upper critical temperature and then cooled slowly in the furnace
Heated below or closes to the lower critical temperature and then cooled slowly
Shock resisting steels should have
Low wear resistance
Low hardness
Low tensile strength
Toughness
Ball bearings are, usually, made from
Low carbon steel
High carbon steel
Medium carbon steel
Chrome steel
Brass contains
70% copper and 30% zinc
90% copper and 10% tin
85 - 92% copper and rest tin with little lead and nickel
70 - 75% copper and rest tin
Which of the following element results in presence of free graphite in C.I.?
Carbon
Sulphur
Silicon
Manganese
The percentage of carbon in low carbon steel is
0.05 %
0.15 %
0.3 %
0.5 %
Dye penetrant method is generally used to locate
Core defects
Surface defects
Superficial defects
Temporary defects
Hardness of martensite is about
RC 65
RC 48
RC 57
RC 80
The material widely used for making pendulums of clocks is
Stainless steel
High speed steel
Heat resisting steel
Nickel steel
Quenching is not necessary when hardening is done by
Case hardening
Flame hardening
Nitriding
Any one of these
The alloy used for making electrical resistances and heating elements is
Nichrome
Invar
Magnin
Elinvar