RRB JE Mechanical- Material Science Questionbank 1

Mechanical-Engineering

Fatigue failure in materials occurs due to —-? RRB JE (Re-Exam) 04.06.2025

constant stress
high temperature
cyclic loading
low temperature

Explanation:

Fatigue failure occurs due to cyclic loading. When the magnitude or direction of load changes frequently with time, it is termed as fluctuating or fatigue loading. Fatigue is the progressive and localized structural damage that occurs under cyclic loading.

Which test is commonly used to measure the malleability of a material? RRB JE (Re-Exam) 04.06.2025

Torsion test
Compression test
Hardness test
Impact test

Explanation:

Compression test is commonly used to measure the malleability of a material. Malleability is the ability of a material to deform under compressive stress without fracturing. Impact test is done to test toughness using Izod and Charpy testing machines.

What happens to the mechanical properties of mild steel when carbon content increases? RRB JE (Re-Exam) 04.06.2025

Strength decreases and ductility increases
Both strength and hardness decrease
Strength increases and ductility decreases
Both strength and ductility increase

Explanation:

As carbon content increases in mild steel, ultimate strength increases, ductility decreases, elongation before fracture decreases, and weldability reduces (especially above 0.25% carbon). Hardness and hardenability also improve.

The diagram below shows the stress-strain curves of two materials, Material A and Material B. Material A has a finer grain structure, while Material B has a coarser grain structure. Based on the diagram, which of the following statements is correct regarding their toughness? RRB JE (Re-Exam) 04.06.2025

Material A (finer grain size) has lower toughness than Material B (coarser grain size)
Both materials have the same toughness, as indicated by their identical total strain values
Material A (finer grain size) has higher toughness than Material B (coarser grain size)
Toughness can be determined directly by comparing the slopes of the stress-strain curves

Explanation:

Toughness is represented by the area under the stress-strain curve up to the fracture point. Material A curve encompasses a larger area than Material B, therefore Material A has higher toughness.

Which of the following is true about the weldability of mild steel and alloy steel? RRB JE (Re-Exam) 04.06.2025

Alloy steel is easier to weld than mild steel
Weldability depends only on the thickness of the steel
Mild steel is easier to weld than alloy steel
Both mild and alloy steel have the same weldability

Explanation:

Weldability order: Iron > Mild steel > Low alloy steel > Stainless steel > Aluminium > Copper. Mild steel is easier to weld than alloy steel.

A material exhibits a large amount of plastic deformation before fracture and can absorb significant energy. This material is said to have —-? RRB JE (Re-Exam) 04.06.2025

high hardness
high strength
high modulus of elasticity
high toughness

Explanation:

High toughness means material exhibits large plastic deformation before fracture and can absorb significant energy. Hardness resists indentation, strength resists fracture under load, and modulus of elasticity is the ratio of stress to strain in the elastic region.

What is the typical behaviour of creep deformation in materials at very high temperatures (above 0.5 times the melting temperature)? RRB JE Stage 2 (22.04.2025 9:00 AM-11:00 AM)

Material exhibits significant plastic deformation
Deformation in material is negligible
Rapid deformation and fractures
Material becomes more brittle and fails instantly

Explanation:

Creep is time-dependent deformation when material is subjected to constant load at elevated temperature (>0.4-0.5 times melting temperature). It occurs in three stages and is affected by material properties, exposure time, temperature, and structural load.

Why does cast iron have high compressive strength but low tensile strength? RRB JE Stage 2 (22.04.2025 9:00 AM-11:00 AM)

Due to its elastic properties
Due to the presence of graphite flakes
Due to its ductile nature
Due to its high malleability

Explanation:

Cast iron has high compressive strength but low tensile strength due to the presence of graphite flakes or nodules in its microstructure, which enhance its ability to withstand compression loads.

Which type of steel would be best suited for applications requiring both high strength and good corrosion resistance? RRB JE Stage 2 (22.04.2025 9:00 AM-11:00 AM)

High-carbon steel
Stainless steel
Mild steel
Low-alloy steel

Explanation:

Presence of Chromium in steel provides corrosion resistance. Stainless steel contains a minimum of 10.5% chromium by mass and less than 1.2% carbon.

The Vickers hardness number (VHN) for a material with a 20 kg load and an average indentation diagonal of 0.3 mm is —-? RRB JE Stage 2 (22.04.2025 9:00 AM-11:00 AM)

78
412
324
115

Explanation:

VHN = 1.854 × F / d² = 1.854 × 20 / (0.3)² = 37.08 / 0.09 = 412

Which area under the stress-strain curve represents the toughness of a material? RRB JE Stage 2 (22.04.2025 9:00 AM-11:00 AM)

Total area under the curve
Area of plastic region
Slope of the elastic region
Area of elastic region

Explanation:

The total area under the entire stress-strain curve represents the toughness of a material.

Which type of light is generally used in the photo etching process? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

X-ray
Ultraviolet (UV) light
Infrared (IR) light
Visible light

Explanation:

Ultraviolet (UV) light is generally used in the photo etching process, which involves applying a photographic image onto a metal surface and etching away the exposed area to create the pattern.

In the Charpy impact test, the specimen is typically —-? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

a cylindrical rod with no defects
subjected to a gradual tensile load
a rectangular bar with a notch in the middle
a sheet of material placed under compression

Explanation:

The Charpy impact test (Charpy V-notch test) determines the energy absorbed by a material during fracture. The specimen is a rectangular bar with a U-shaped or V-shaped notch.

Which of the following material has the highest compressive strength? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

Copper
Rubber
Mild Steel
Cast Iron

Explanation:

Cast iron has compressive strength in the range of 600-700 MPa. Mild steel: 250-400 MPa. Rubber: 10-20 MPa.

If a component has a Factor of Safety (FOS) of 1.0, what does it indicate? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

The component will never fail irrespective of any load
The design is highly conservative
The material will fail exactly at the expected load
The design is unsafe and should not be designed

Explanation:

FOS of 1.0 indicates the component is at the point of failure. FOS is the ratio of maximum stress a material can withstand to the actual stress applied.

Which type of fracture is most likely to occur in a material with high tensile strength but low ductility? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

Brittle fracture
Ductile fracture
Creep failure
Fatigue failure

Explanation:

Brittle fracture is catastrophic failure that occurs without significant plastic deformation. It is most common in materials with high tensile strength but low ductility.

The S-N curve in fatigue testing shows the relationship between —-? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

stress and strain
the number of cycles and strain amplitude
the number of cycles and stress amplitude
stress and displacement

Explanation:

The S-N curve plots number of cycles to failure (N) on logarithmic scale on x-axis and stress amplitude on y-axis.

Which of the following factors generally increases the brittleness of a material? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

Low temperature
High alloy content
High strain rate
High temperature

Explanation:

Low temperature generally increases brittleness of a material.

In which of the following situations would brittleness be most UNDESIRABLE? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

In materials exposed to high temperatures
In tools that need to withstand heavy impact
In structural beams under static load
In materials used in high-speed applications

Explanation:

Brittleness is most undesirable in tools that need to withstand heavy impact because brittle materials break or shatter without significant deformation and absorb very little energy before fracture.

The metals can be beaten into thin sheets, the property is called —-? RRB JE 29-08-2019

Ductility
Malleability
Lustre
Sonority

Explanation:

Malleability is the property by which metals can be beaten into thin sheets. Malleability decreasing order: Lead > Soft steel > Wrought iron > Copper > Aluminium.

Which of the following properties is desirable in parts subjected to shock and impact loads? RRB JE 29-08-2019

Strength
Toughness
Stiffness
Brittleness

Explanation:

Toughness is the property to resist fracture due to high impact loads like hammer blow, desirable in parts subjected to shock and impact loads.

The unit of modulus of rigidity is the same as those of —-? RRB JE 29-08-2019

Stress, pressure and modulus of elasticity
Strain, force and pressure
Stress, strain and pressure
Stress, force and modulus of elasticity

Explanation:

Modulus of rigidity (G) = Shear stress / Shear strain. Unit of shear stress is N/mm², shear strain has no unit. So unit of modulus of rigidity is N/mm², same as stress, pressure, and modulus of elasticity.

Which of the following materials has the maximum ductility? RRB JE 29-08-2019

Aluminium
Nickel
Tungsten
Iron

Explanation:

Aluminium has maximum ductility among the given options. Ductility decreasing order: Gold > Mild steel > Copper > Aluminium > Nickel > Zinc > Tin > Lead.

Creep, a high temperature progressive deformation, occurs in …… stages. RRB JE 29-08-2019

Two
Three
Four
Five

Explanation:

Creep occurs in three stages: Primary (transition state), Secondary (steady-state), Tertiary (strain rate exponentially increases with stress).

Which of the following is/are a ferromagnetic material? RRB JE 29-08-2019

Tungsten
Nickel
Copper
Aluminium

Explanation:

Ferromagnetic materials are strongly attracted by magnets and do not lose magnetism on removal of external magnetic field. Examples: Iron, Nickel, and Cobalt.

Which of the following is a slow rise of plastic deformation under the action of stresses? RRB JE 29-08-2019

Fatigue
Brittle fracture
Ductile fracture
Creep

Explanation:

Creep is slow and permanent deformation when a component is subjected to constant stress at high temperature for a long period. This property is considered in designing IC engines, boilers, and turbines.

Litmus, a natural dye, is an extract of —-? RRB JE 29-08-2019

Lichen
Blue berries
Beet root
China rose

Explanation:

Litmus is extracted from Lichen, which is a composite organism that emerges from algae.

What is the melting point of zinc? RRB JE 30-08-2019

621°F
787°F
2646°F
1204°F

Explanation:

Melting point of zinc is 787°F (420°C). Aluminium: 660°C, Brass: 930°C, Copper: 1084°C, Cast iron: 1204°C.

In queuing theory, the ratio of the mean arrival rate and the mean service rate is called the —-? RRB JE 30-08-2019

Work factor
Utilization factor
Slack constant
Productivity rate

Explanation:

Utilization factor ρ = λ/μ in queuing theory.

The binding material used in cemented carbide tools is —-? RRB JE 30-08-2019

Silicon
Tungsten
Cobalt
Chromium

Explanation:

Cobalt is the binding material used in cemented carbide tools. Cemented carbide consists of fine carbide particles cemented into a composite by a binder metal.

Which of the following material has maximum malleability? RRB JE 30-08-2019

Wrought iron
Lead
Soft Steel
Copper

Explanation:

Lead has maximum malleability. Malleability decreasing order: Lead > Soft steel > Wrought iron > Copper > Aluminium.

Give an example of a metal which can be easily cut with a knife. RRB JE 30-08-2019

Mercury
Sodium
Silver
Iron

Explanation:

Sodium can be cut with a knife easily because it is a very soft silvery-white metal. It occurs abundantly as sodium chloride (NaCl).

The ability of a material to absorb energy in the elastic region is called —-? RRB JE 31-08-2019

Resilience
Toughness
Ductility
Hardness

Explanation:

Resilience is the ability of material to absorb energy in the elastic region. Resilience = Area under elastic region = ½ × P × δ. Maximum Resilience or proof resilience is up to the elastic point.

Gun metal contains 2 percent of —-? RRB JE 31-08-2019

Tin
Zinc
Copper
Nickel

Explanation:

Gun metal is an alloy of 88% copper, 10% tin, and 2% zinc. Zinc is added to clean the metal and increase its fluidity.

The electron distribution in a magnesium atom is —-? RRB JE 31-08-2019

8.2.2
2.8.3
2.8.2
8.2.3

Explanation:

Magnesium has 12 electrons distributed as K shell-2, L shell-8, M shell-2 (2.8.2).

In Rockwell hardness testing method, the hardness of a material is measured by —-? RRB JE 31-08-2019

Material failure
Depth of indentation
Elongation of material
Surface roughness

Explanation:

Rockwell Hardness test measures hardness by depth of indentation. It has nine scales (A to H and K), with B and C scales most widely used.

Which of the following is an example of paramagnetic material? RRB JE 31-08-2019

Gold
Tantalum
Copper
Silver

Explanation:

Paramagnetic substances get weakly magnetised in the direction of the magnetising field. Examples: Tantalum, Aluminium, Chromium, Manganese, Platinum, Tungsten.

Which theory of failure will you use for aluminium components under steady loading? RRB JE 31-08-2019

Maximum strain energy theory
Maximum shear stress theory
Maximum principal stress theory
Maximum principal strain theory

Explanation:

Maximum shear stress theory is applicable for ductile materials. Aluminium is a ductile material, so maximum shear stress theory is used.

The malleability is the property of a material by virtue of which a material —-? RRB JE 31-08-2019

Retains the deformation produced under load permanently
Regains its shape and size after the removal of external forces
Can be drawn into wires with the application of a tensile force
Can be rolled or hammered into thin sheets

Explanation:

Malleability is the property by which a material can be rolled or hammered into thin sheets. Gold is most malleable and ductile, but in engineering practice, lead is more malleable.

The failure of the material due to cyclic loads is known as —-? RRB JE 31-08-2019

Impact failure
Creep
Fatigue
Embrittlement

Explanation:

Fatigue is failure due to cyclic or repeated stresses at stresses below yield point. Fatigue/Endurance stress for steel: 0.5σu, Cast steel: 0.4σu, Cast iron: 0.35σu, Non-ferrous: 0.3σu.

Which of the following elements has maximum atomic radius? RRB JE 31-08-2019

Explanation:

Sodium (Na) has highest Vander Waals atomic radius (227 pm). S: 180 pm, P: 195 pm, Cl: 175 pm.

____ has maximum malleability. (RRB Bhopal SSE 09.09.2012) (DMRC 18.02.2017, 8.30 a.m.)

Aluminium
Copper
Lead
Wrought iron

Explanation:

Lead has maximum malleability. Malleability decreasing order: Lead > Soft steel > Wrought iron > Copper > Aluminium.

Fluidity is greatly influenced by —-? (RRB Jammu JE 25.10.2009)

carbon content of molten metal
melting temperature of molten metal
inoculant addition
pouring temperature of molten metal

Explanation:

Fluidity is greatly influenced by pouring temperature of molten metal. Fluidity is the ability of molten metal to flow smoothly to fill the cavity. Higher pouring temperature increases fluidity, improves surface finish, decreases density and viscosity.

Hardness of steel depends on —-? (RRB Allahabad SSE 09.09.2012)

amount of cementite it contains
amount of carbon it contains
contents of alloying elements
method of manufacture of steel

Explanation:

Hardness of steel depends on the amount of carbon. Maximum attainable hardness depends solely on carbon content, also affected by carbon distribution.

____ is added to raise the yield point of low carbon steel. (RRB Kolkata SSE 09.09.2012)

Silicon
Carbon
Phosphorous
Sulphur

Explanation:

Phosphorous is added to raise the yield point of low carbon steel. Phosphorous makes steel brittle, produces cold shortness, and improves corrosion resistance. Silicon prevents porosity.

Which of the following materials has the maximum ductility? (RRB Chandigarh SSE 25.10.2009)

Aluminium
Nickel
Tungsten
Iron

Explanation:

Aluminium has maximum ductility among the given options. Ductility decreasing order: Gold & Platinum > Mild steel > Copper > Aluminium > Nickel > Zinc > Tin > Lead.

If T is the recrystallization temperature, the cold working of steel is done at —-? (RRB Bhubneshwar JE II 29.11.2008)

greater than T°C
equal to T°C
less than T°C
None of these

Explanation:

Cold working is plastic deformation below recrystallisation temperature, generally at room temperature. Hot working is above recrystallisation temperature.

Alloy steel as compared to carbon steel is more —-? (RRB Bhopal SSE 09.09.2012)

only A (tough)
only B (strong)
only C (fatigue resistance)
None of these (All of the above)

Explanation:

Alloy steel is more tough, strong, and fatigue resistant compared to carbon steel. Alloying elements improve properties. Examples: Invar (prevents thermal expansion), Tool steel (dies, bearings), Silicon Steel (transformer lamination), Stainless steel (surgical tools).

The property of a material by which it can be beaten or rolled into sheets is known as —-? (DMRC 18.02.2017, 8.30 a.m) (RRB Bhubneshwar JE II 29.11.2008)

Malleability
Ductility
Plasticity
Elasticity

Explanation:

Malleability is the property by which material can be beaten or rolled into thin sheets. Malleability is temperature dependent. The most malleable metal is gold.

Which ingredient is responsible for corrosion resistant capability in Stainless Steel? (Konkan Railway SSE 2015) (RRB Mumbai C&G JE 25.10.2009)

Iron
Chromium
Zinc
Sulphur

Explanation:

Chromium is responsible for corrosion resistance in stainless steel. Stainless steel contains at least 10.5% chromium, less than 1.2% carbon, and other alloying elements.

Which one of the following has the highest value of specific stiffness? (RRB Mumbai SSE 19.12.2010)

Steel
Aluminium
Fibre glass
Carbon fibre composite

Explanation:

Specific stiffness = E/ρ (Young’s modulus / density). Steel has the highest value of specific stiffness.

The process of formation of new grains on heating metals is called —-? (Konkan Railway STA 2017)

Recrystallization
Oxidation
Microstructure
Hardening

Explanation:

Recrystallization is the formation of new grains on heating metals. It occurs at 0.3 to 0.7 times the melting point temperature.

The ability of a material to resist softening at high temperature is known as —-? (RRB Mumbai C&G SSE 25.10.2009)

creep
hot tempering
hot hardness
plastic deformation

Explanation:

Hot hardness is the ability of a material to retain its hardness at elevated temperature.

Toughness is related to —-? (RRB Allahabad SSE 09.09.2012)

Moment of inertia
Hardness
Energy absorbed before fracture
Fatigue loading

Explanation:

Toughness is the property to resist fracture due to high impact load. Modulus of toughness is the area under the stress-strain curve up to fracture point.

The machinability of steel can be improved by alloying the steel with —-? (RRB Jammu SSE 09.09.2012)

Copper
Chromium
Nickel
Sulphur

Explanation:

Sulphur, Lead, and Phosphorus improve the machinability of steel.

The important property of a material in all metal forming processes is —-? (DMRC JE 22.09.2017)

elasticity
plasticity
ductility
brittleness

Explanation:

Plasticity is the important property in all metal forming processes. It is the property that retains deformation under load permanently, useful for forming, rolling, extrusion, etc.

The ductility of a material after work hardening —-? (RRB Bhubneshwar JE-II 19.12.2010)

increases
decreases
remains unaltered
None of these

Explanation:

Ductility decreases after work hardening (strain hardening). Work hardening strengthens metal by plastic deformation through dislocation movements and generation.

____ is the point at which new grains structures are formed in the metal. (RRB JE (Shift-1), 28.08.2015) RRB Secunderabad Section Engineer (Mech.) 29.06.2008

Recrystallization temperature
Lower critical temperature
Eutectic temperature
Upper critical temperature

Explanation:

Recrystallization temperature is the point at which new grains are formed in the metal, replacing deformed grains with stress-free grains.

What property of a material enables it to be drawn into wires with the application of tensile force? (JMRC JE 10.06.2017)

Plasticity
Elasticity
Ductility
Malleability

Explanation:

Ductility enables material to be drawn into wires with tensile force. Examples: Copper, Gold, Tin, Wrought iron, Aluminium.

Which of the following materials is most elastic? (RRB Allahabad SSE 19.12.2010)

Rubber
Plastic
Brass
Steel

Explanation:

Elasticity is the property to regain original shape after deformation. Steel is the most elastic.

In a tensile test of a specimen, the ratio of maximum load to the original cross-sectional area of the test piece is called —-? (RRB Mumbai SSE 19.12.2010)

Safe stress
Breaking stress
Yield stress
Ultimate stress

Explanation:

Ultimate tensile strength = Maximum load / Original cross-sectional area.

Stress concentration is caused due to —-? (Konkan Railway STA 2017)

Variation in load acting on a member
Variation in material properties
Abrupt change of cross-section
All of the above

Explanation:

Stress concentration occurs due to abrupt change of cross-section. Stress concentration factor = Maximum stress / Nominal stress.

The resistance to fatigue of material is measured by —-? (RRB Mumbai C&G SSE 25.10.2009) RRB Bangalore Section Engineer (Mech.) 01.02.2009

Elastic limit
Young’s Modulus
Ultimate tensile strength
Endurance limit

Explanation:

Resistance to fatigue is measured by endurance limit – the maximum stress a polished specimen can withstand for infinite cycles under completely reversed load.

A body having same properties throughout its volume is said to be —-? (RRB Allahabad SSE 09.09.2012)

Isotropic
Continuous
Homogeneous
Uniform

Explanation:

A homogeneous material has the same properties throughout its volume. Isotropic materials can be either homogeneous or non-homogeneous.

Which phenomenon is NOT used in the property of hardness? (RRB Kolkata SSE 09.09.2012)

Indentation
Fracture
Wear
Scratch

Explanation:

Hardness embraces resistance to wear, scratching, deformation, and machinability. Fracture is not a property of hardness. Hardness tests force a small indenter into the material surface.

The property of a material which enables it to resist fracture due to high impact loads is known as —-? (RRB Chandigarh SSE 09.09.2012)

elasticity
endurance
strength
toughness

Explanation:

Toughness is the property that enables material to resist fracture due to high impact loads or absorb energy without fracture. Bend test is used for comparative toughness testing.

High elastic modulus in materials arises from —-? (RRB Bhubneshwar JE II 29.11.2008)

High strength of bonds
Weak bonds
Combination of bonds
None of these

Explanation:

High elastic modulus arises from high strength of bonds. Modulus of elasticity is directly proportional to interatomic bonding force.

Which of the following elements is NOT a primary alloying element in stainless steel? RRB JE (Re-Exam) 04.06.2025

Carbon
Nickel
Chromium
Lead

Explanation:

Lead is not a primary alloying element in stainless steel. Stainless steel composition: Nickel (18%), Chromium (8%), Carbon (0.12% to 0.35%), rest iron.

Why does stainless steel resist rusting, while regular carbon steel does not? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

Stainless steel has higher carbon content which makes it corrosion resistant
Stainless steel is coated with a special anti-rust chemical
Stainless steel has a thicker iron content
Stainless steel has a protective chromium oxide layer that prevents rusting

Explanation:

Stainless steel has a protective chromium oxide layer that prevents rusting by blocking oxygen and moisture. This layer is self-healing. Regular carbon steel lacks this protective layer.

Which alloying element in alloy steel is primarily responsible for enhancing corrosion resistance? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

Silicon
Manganese
Chromium
Carbon

Explanation:

Chromium is primarily responsible for enhancing corrosion resistance. It improves oxidation resistance, forms a self-healing protective oxide layer, enhances hardness and wear resistance, and increases tensile strength.

Which of the following types of steel would NOT typically undergo the normalizing process? RRB JE Stage 2 (22.04.2025 2:30-4:30 PM)

Medium-carbon steel
High-carbon steel
Stainless steel
Alloy steel

Explanation:

Stainless steel is typically not normalized because it contains alloying elements (chromium, nickel, molybdenum) that provide corrosion resistance. Normalizing is used to refine grain structure and remove internal stresses.

A steel with 0.8% carbon and 100% pearlite is called —-? RRB-JE 29.08.2019, Ist Shift

Eutectoid steel
Hypo-eutectoid steel
Hyper eutectoid steel
Pro eutectoid steel

Explanation:

Eutectoid steel has 0.8% carbon. Hypo-eutectoid: 0.008% – 0.8% carbon. Hyper-eutectoid: 0.8% – 1.7% carbon.

Which of the following materials has nearly zero coefficient of expansion? RRB JE 29-08-2019

Silver
Selenium
Invar
Stainless Steel

Explanation:

Invar is a nickel steel alloy containing about 36% nickel with nearly zero coefficient of expansion, used for pendulums and precision instruments.

Malleable cast iron is produced —-? RRB JE 30-08-2019

From white cast iron by the annealing process
From white cast iron by the carburizing process
By adding magnesium to molten cast iron
By quick cooling of molten cast iron

Explanation:

Malleable cast iron is produced from white cast iron by the annealing process.

The lower critical point for all steels is —-? RRB JE 31-08-2019

600°C
723°C
800°C
913°C

Explanation:

The lower critical point for all steels is 723°C, where austenite starts to transform from ferrite. Lower critical point is where changes start on heating, upper critical point is where changes end.

Which of the following is the most common substrate material for hot-dip metallic coating? (BMRCL JE 24 Feb. 2019)

Aluminium
Steel
Zinc
Terene

Explanation:

Steel is the most common substrate for hot-dip metallic coating to prevent corrosion. The process involves immersing iron or steel in molten zinc or low melting metal.

If carbon present in cast iron is partly free and partly in combined state, it is called —-? (BMRCL JE 24 Feb. 2019)

White cast iron
Grey cast iron
Molten cast iron
None of these

Explanation:

White cast iron has carbon partly free and partly in combined state (as cementite). It has 1.75 to 2.3% carbon, high tensile strength, and low compressive strength.

Increasing carbon content in steel, ultimate strength and … ductility of steel. (RRB Allahabad JE 19.12.2010)

increases, decreases
decreases, decreases
increases, increases
decreases, increases

Explanation:

Increasing carbon content increases ultimate strength and hardness, but decreases ductility. Brittleness increases and machining becomes difficult.

According to Indian standard designation, high alloy steel 30Cr 13 contains which of the following composition of %? DMRC JE 17.04.2018 12:15-2:30 PM

0.08 max (C), 1.0 (Si), 2.0 (Mn)
0.40-0.50 (C), 3.25-3.75 (Si), 0.30-0.60 (Mn)
0.26-0.35 (C), 1.0 max (Si), 1.0 max (Mn)
0.12 max (C), 1.0 (Si), 2.0 (Mn)

Explanation:

30Cr 13 contains 0.26-0.35% carbon, Silicon maximum 1%, Manganese maximum 1%.

The open hearth process of steel making is sometimes called —-? DMRC JE 17.04.2018 12:15-2:30 PM

Siemens-Martin process
Thomas process
White hearth process
Aston or Byers process

Explanation:

Open hearth process is also called Siemens-Martin process. It burns excess carbon and impurities out of pig iron to produce steel.

Tool steel contains… of carbon. DMRC JE 17.04.2018 12:15-2:30 PM

0.6%
0.03%
0.05%
0.9%

Explanation:

Tool steel contains 0.9% carbon. High carbon gives hardness and strength. Used for tools like chisels, hammers, drills, taps, and machine parts requiring high strength.

Austenitic stainless steel contains —-? DMRC JE 17.04.2018, 4:30-6:45pm (RRB Mumbai SSE 05.10.2008)

18% chromium and 8% nickel
8% chromium and 18% nickel
14% chromium and 0.35% carbon
14% nickel and 0.35% carbon

Explanation:

Austenitic stainless steel contains high content of both chromium and nickel – 18% chromium and 8% nickel (18/8 steel).

Composition of HSS 18:4:1 is? DMRC JE 2013 (Konkan Railway STA 2017)

18% W, 4% Cr, 1% V
18% Cr, 4% W, 1% V
18% W, 4% Ni, 1% Cr
18% Cr, 4% Ni, 1% W

Explanation:

HSS composition: 18% Tungsten (increases hot hardness), 4% Chromium (increases strength and resistance to deformation), 1% Vanadium (improves wear resistance).

18/8 stainless steel consists of —-? (Konkan Railway SSE 2015) (RRB Mumbai C&G JE 25.10.2009)

18% Nickel and 8% Chromium
18% Chromium and 8% Nickel
18% Vanadium and 8% Chromium
18% Nickel and 8% Vanadium

Explanation:

18/8 stainless steel consists of 18% chromium and 8% nickel. This is the most widely used austenitic stainless steel.

Which of the following decreases as the percentage of carbon increases in steel? (RRB Mumbai C&G SSE 25.10.2009)

Ductility
Brittleness
Strength
Hardness

Explanation:

As carbon percentage increases in steel, strength, hardness, and brittleness increase while ductility decreases.

High speed steel tool material contains carbon —-? (RRB Mumbai C&G SSE 25.10.2009) (RRB Allahabad SSE 09.09.2012)

0.6%–1.0%
2.0%–4.3%
0.6%–4.3%
6%–10%

Explanation:

HSS contains 0.7% carbon along with 18% W, 4% Cr, 1% V, rest Fe. Properties: high wear resistance, high working hardness, excellent toughness, high hot hardness.

Cast iron is characterized by minimum of following %age of carbon —-? (RRB Kolkata SSE 09.09.2012) (DMRC JE 2013)

0.2%
0.8%
1.3%
2%

Explanation:

Cast iron has minimum 2% carbon (up to 4.5%). It is primarily an alloy of iron and carbon, obtained by remelting pig iron with coke and limestone in a cupola furnace.

The ingredient of high speed steel of T series are —-? (RRB Bhopal SSE 09.09.2012)

Vanadium, chromium and tungsten
Vanadium, chromium and cobalt
Vanadium, cobalt and Nickel
Chromium, Nickel and steel

Explanation:

T series HSS contains Tungsten (W-18%), Chromium (Cr-4%), and Vanadium (V-1%). These ingredients make HSS hard, strong, and wear resistant.

A carbon steel contains 1% carbon. It is to be converted to 0.5% carbon. Amount of iron to be added to 10 kg of this steel is —-? (RRB Jammu SSE 09.09.2012)

15 kg
10 kg
5 kg
20 kg

Explanation:

Carbon in 10 kg of 1% steel = 0.1 kg. Let x kg iron added. (10+x) × 0.5/100 = 0.1. 10+x = 20, x = 10 kg.

Chromium in steel —-? (RRB Bhubneshwar JE II 29.11.2008) (DMRC JE 2013)

Improves wear resistance, cutting ability and toughness
Refines grain size and produces less tendency to carburisation
Improves cutting ability and reduces hardenability
Gives ductility, toughness, tensile strength and anticorrosion properties

Explanation:

Chromium in steel improves toughness, wear resistance, tensile strength, and corrosion resistance.

Alloy steel containing 23 to 30% chromium with carbon less than 0.35% is known as —-? DMRC JE 17.04.2018, 4:30-6:45pm

Shock-resistance steel
Heat-resistance steel
Magnet steel
Stainless steel

Explanation:

Alloy steel with 23-30% chromium and carbon less than 0.35% is heat-resistance steel.

Percentage of carbon in high carbon steel is —-? (RRB Jammu JE 25.10.2009)

0.15 ± 0.25%
0.25 ± 0.5%
0.6 ± 1.4%
Greater than 1.8%

Explanation:

High carbon steel contains 0.8% to 1.5% carbon. Dead mild steel: 0.15% or less. Low/mild steel: 0.15% to 0.45%. Medium carbon steel: 0.45% to 0.8%.

Percentage of carbon in Cast Iron is —-? (DMRC JE 20.04.2018) (Konkan Railway SSE 2015)

0%
0 to 1%
1% to 2%
2% to 4%

Explanation:

Cast iron contains 2% to 4% carbon, present either as free form or combined form. Properties: Low heat, good casting characteristics, high compressive strength, wear resistance, excellent machinability.

Match the following related to type of steel and its product: (RRB Mumbai C&G JE 25.10.2009)

A-3, B-4, C-1, D-2
A-4, B-1, C-2, D-3
A-3, B-2, C-4, D-1
A-4, B-3, C-1, D-2

Explanation:

Mild steel → Commercial beams (4), Tool steel → Milling cutters (3), Medium carbon steel → Hammers (1), High carbon steel → Crane hooks (2).

Which material is most commonly used for manufacturing of machine tool bed? (RRB Malda SSE 25.10.2009) (DMRC JE 22.09.2017)

Mild steel
Grey cast iron
White cast iron
Galvanized iron

Explanation:

Machine tool beds are made of grey cast iron due to its high compressive strength and excellent damping characteristics.

Stainless-Steel is highly corrosion resistant mainly due to the presence of —-? (BMRC JE 24 Feb. 2019) (RRB JE Bhopal Paper-1 (Shift-11), 28.08.2015)

Copper
Vanadium
Carbon
Chromium

Explanation:

Chromium provides corrosion resistance to steel. Chrome steel containing 0.5 to 2% chromium is used for balls, rollers, bearings, dies, and permanent magnets.

The carbon present in cast irons may occur in the chemically combined form known as —-? (RRB Mumbai JE 19.12.2010) RRB Chandigarh Section Engineer, 15.03.2009

Ferrite
Pearlite
Cementite
Steadite

Explanation:

Cementite (Fe3C) is a compound of iron and carbon – 6.67% carbon and 93.3% iron. It is hard and brittle, thermodynamically unstable, converting to austenite and graphite at higher temperatures.

____ is present in high percentage in magnet steel. (RRB Mumbai JE 19.12.2010)

Aluminium
Tungsten
Zinc
Copper

Explanation:

Tungsten is present in high percentage in magnet steel. Tungsten forms tungsten carbide and every element of tungsten carbide is susceptible to magnetism.