Metal Forming Process · Metal Forming · GATE PI

A steel wire of $$2$$ $$mm$$ diameter is to be drawn from a wire of $$5mm$$ diameter. The value of true strain developed is _____________ (up to three decimal places)

The true stress at fracture of a tensile tested specimen, having an initial diameter of specimen at fracture is $$10$$ $$mm,$$ then the engineering stress, in $$MPa,$$ at fracture is ____________

In rolling of a flat strip, the relative velocity of strip with respect to the roller is

The maximum reduction per pass during wire drawing of an aluminium alloy ignoring friction and redundant work is $$77\% $$. The strain hardening exponent of the material is ______________.

In an open die forging, a circular disc is gradually compressed between two flat plates. The exponential decay of normal stress on the flat face of the disc, from the center of the disc towards its periphery, indicates that

A moving mandrel is used in

In a rolling process, the state of stress of the material undergoing deformation is

A solid cylinder of diameter $$100$$ $$mm$$ and height $$50$$ $$mm$$ is forged between two frictionless flat dies to a height of $$25$$ $$mm.$$ The percentage change in diameter is

Hot die steel, used for large solid dies in drop forging, should necessarily have

Cold shut (lap) may occur in products obtained by:

Anisotropy in rolled components is caused by

Flash and gutter are provided in drop forging dies at the following stage:

Cold shut (lap) may occur in products obtained by:

In order to reduce roll pressure in strip rolling, back tension must be applied to strip.

Which one of the following manufacturing process requires the provision of 'gutters'

A moving mandrel is used in

Forces in hot extrusion is a function of the strain hardening component of the billet material.

In order to reduce roll pressure in strip rolling, back tension can be applied to strip.

Thread rolling is restricted to

At $${1000^ \circ }C$$ the crystallographic structure of iron is ....................

Seamless long steel tubes are manufactured by rolling, drawing and .............

Semi brittle materials can be extruded by

While rolling a strip the peripheral velocity of the roll is ..... A .... than the entry velocity of the strip and is ...... B .... the exit velocity of the strip
A. greater / less / equal to
B. greater than / less than / equal to

The blank diameter used in thread rolling will be

Collapsible tubes are made by

At the last hammer stroke the excess material from the finishing cavity of a forging die is pushed into .............

A metallic strip having a thickness of $$12$$ $$mm$$ is to be rolled using two steel rolls, each of $$800$$ $$mm$$ diameter. It is assumed that there is no change in width of the strip during rolling. In order to achieve $$10\% $$ reduction in cross-sectional area of the strip after rolling, the angle subtended (in degrees) by the deformation zone at the center of the roll is

In a single-pass rolling operation, a $$200$$ $$mm$$ wide metalic strip is rolled from a thickness $$10$$ $$mm$$ to a thickness $$6$$ $$mm.$$ The roll radius is $$100$$ $$mm$$ and it rotates at $$200$$ $$rpm$$. The roll-strip contact length is a function of roll radius and, initial and final thickness of the strip. If the average flow stress in plane strain of the strip material in the roll gap is $$500$$ $$MPa$$, the roll separating force (in $$kN$$) is _________________

Two solid cylinders of equal diameter have different heights. They are compressed plastically by a pair of rigid dies to create the same percentage reduction in their respective heights. Consider that the die-work-piece interface friction is negligible. The ratio of the final diameter of the shorter cylinder to that of the longer cylinder is _________________.

Open die forging of a cylinder made of a rigid perfectly plastic material with yield strength of $$200$$ $$MPa$$ having a height of $$25$$ $$mm$$ and diameter of $$25$$ $$mm$$ is being carried out. The cylinder is subjected to a true compressive strain of $$3.6$$ during the process. Assuming frictionless and homogeneous deformation, the energy expended, in $$kJ$$ is __________________.

A $$80$$ $$mm$$ thick steel plate with $$400$$ $$mm$$ width is rolled to $$40mm$$ thickness in $$4$$ passes with equal reduction in each pass, by using rolls of $$800mm$$ diameter. Assuming the plane-strain deformation, what is the minimum coefficient of friction required for unaided rolling to be possible?

In a single pass rolling process using $$410mm$$ diameter steel rollers, a strip of width $$140mm$$ and thickness $$8mm$$ undergoes $$10\% $$ reduction of thickness. The angle of bite in radians is

In multi-pass operation, a round bar of $$10$$ $$mm$$ diameter and $$100$$ $$mm$$ length is reduced in cross-section by drawing it successively through a series of seven dies of decreasing exit diameter. During each of theses drawing operations, the reduction in cross-sectional area is $$35\% $$. The yield strength of the material is $$200$$ $$MPa.$$ Ignore strain hardening.

The total true strain applied and the final length (in $$mm$$), respectively, are

The thickness of a plate is reduced from $$30$$ $$mm$$ to $$10$$ $$mm$$ by successive cold rolling passes using identical rolls of diameter $$600$$ $$mm.$$ Assume that there is no change in width. If the coefficient of friction between the rolls and the work piece is $$0.1,$$ the minimum number of passes required is

In multi-pass operation, a round bar of $$10$$ $$mm$$ diameter and $$100$$ $$mm$$ length is reduced in cross-section by drawing it successively through a series of seven dies of decreasing exit diameter. During each of theses drawing operations, the reduction in cross-sectional area is $$35\% $$. The yield strength of the material is $$200$$ $$MPa.$$ Ignore strain hardening.

Neglecting friction and redundant work, the force (in $$kN$$) required for drawing the bar through the first die, is

In a rolling process, the roll separating force can be decreased by

During open die forging process using two flat and parallel dies, a solid steel disc of initial radius $$({R_{IN}})\,\,200mm$$ and Initial height $$({H_{IN}})\,\,50mm$$ attains a height $$({H_{FN}})$$ of $$30mm$$ and radius of $${R_{FN}}$$. Along the die-disc interfaces

(i) The coefficient of friction $$\left( \mu \right)$$ is :
$$\,\,\,\,\,\,\,\mu = 0.35\left[ {1 + {e^{ - {R_{IN}}/{R_{FN}}}}} \right]$$

(ii) In the region $${R_{SS}}\,\, \le \,\,r\,\, \le \,\,{R_{FN}},$$ sliding friction prevails and
$$\,\,\,\,\,\,P = \sqrt 3 .K.{e^{2\mu \left( {{R_{IN}} - r} \right)/{H_{FN}}}}$$ and $$\tau = \mu \,p$$

Where $$p$$ and $$\tau $$ are the normal and the shear stress respectively; $$K$$ is the shear yield strength of steel and $$r$$ is the radial distance of any point
(i) In the region $$0\, \le \,r\, \le \,{R_{IN}}.$$ sticking condition prevails

The value of $$RSS$$ (in $$mm$$ ), where sticking condition changes to sliding friction is

Using direct extrusion process, a round billet of $$100$$ $$mm$$ length and $$50mm$$ diameter is extruded. Considering an ideal deformation process (no friction and no redundant work), extrusion ratio $$4$$ and average flow stress of material $$300$$ $$MPa,$$ the pressure $$(MPa)$$ on the $$ram$$ will be

In a rolling process, thickness of a strip is reduced from $$4mm$$ to $$3mm$$ using $$300mm$$ diameter rolls rotating at $$100rpm.$$ The velocity of the strip (in $$m/sec$$) at the neutral point is

A $$10mm$$ diameter annealed steel wire is drawn through a die at a speed of $$0.5/sec$$ to reduce the diameter by $$20\% $$. The yield stress of the material is $$800MPa.$$

The power required for the drawing process (in $$kW$$ ) is

By application of tensile force, the cross sectional area of bar $$' P '$$ is first reduced by $$30\% $$ and then by an additional $$20\% $$. Another bar $$'Q'$$ of the same material is reduced in cross sectional area by $$50\% $$ in a single step by applying tensile force. After deformation, the true strain in bar $$'P'$$ and bar $$'Q'$$ will, respectively, be

A $$10mm$$ diameter annealed steel wire is drawn through a die at a speed of $$0.5/sec$$ to reduce the diameter by $$20\% $$. The yield stress of the material is $$800MPa.$$

Neglecting friction and strain hardening, the stress required for drawing (in $$MPa$$) is

The maximum possible percentage reduction in area per pass during wire drawing of an ideal plastic material without friction is of the order of

A copper strip of $$200$$ $$mm$$ width and $$30$$ $$mm$$ thickness is to be rolled to a thickness of $$25$$ $$mm.$$ The roll of radius $$300$$ $$mm$$ rotates at $$100$$ $$rpm.$$ The average shear strength of the work material is $$180$$ $$MPa.$$ The roll strip contact length and the roll force are

A solid cylindrical stainless steel work piece of $$200mm$$ diameter and $$150mm$$ height. This component is reduced by $$50\% $$ in height with flat die in open die forging. Assuming the flow stress of the material as $$1000$$ $$MPa$$ and the coefficient of friction to be $$0.2,$$ the estimated forging force at the end of the stroke is

Consider the following statements:
In comparison to hot working, in cold working,
$$1.$$ Higher forces are required
$$2.$$ No heating is required
$$3.$$ Less ductility is required
$$4.$$ Better surface finish is obtained.

Which of the statements given above are correct?

Assertion (A) : Cold working of metals result in increase of strength and hardness.
Reason (R) : Cold working reduces the total number of dislocations per unit volume of the material.

The true stress-true strain curve is given by $$\sigma = 1400\,{\varepsilon ^{0.33}},$$ where the stress $$\sigma $$ is in $$MPa.$$ The true stress at maximum load (in $$MPa$$) is

A level having $${90^0}$$ bend is to be produced by drop forging using mild steel bar as raw material. The various operations to be performed on it during forging are:
$$P$$ - Cutting;
$$Q$$ - Bending;
$$R$$ - Fullering;
$$S$$ - Blocking cum finishing;
$$T$$ - Edgering

The correct sequence for performing the operations is:

A round billet made of brass is to be extruded (extrusion constant $$=250$$ $$MPa$$ ) at $${700^ \circ }C.$$ The billet diameter is $$100$$ $$mm$$ and the diameter of the extrusion is $$50$$ $$mm.$$ The extrusion force required (in $$MN$$) is

The extrusion process(es) used for the production of toothpaste tubes is / are

$$1.$$ Tube extrusion
$$2.$$ Forward extrusion
$$3.$$ Impact extrusion

Cold working produces the following effects

$$1.$$$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ Stress are set up in the material
$$2.$$$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ Grain structure get distorted
$$3.$$$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ Strength and hardness of the metal are decreased
$$4.$$$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ Surface finish is reduced

Consider the following steps in forging a connecting rod from the bar stock

$$1.$$ blocking $$\,\,\,\,\,\,\,\,\,$$ $$\,\,\,\,\,\,\,\,\,$$ $$\,\,\,\,\,\,\,\,\,$$$$2.$$ trimming
$$3.$$ finishing$$\,\,\,\,\,\,\,\,\,$$ $$\,\,\,\,\,\,\,\,\,$$ $$\,\,\,\,\,\,\,\,\,$$ $$4.$$ edging

Select the correct sequence of these operations using the codes given below

An annealed copper wire of $$25 mm$$ diameter is drawn into a wire of $$5$$ $$mm$$ dia. The average yield stress in this operation if the flow curve of the material is given
$$\sigma = 315{ \in ^{0.54}}\,MPa$$

To stress relive a cold worked steel part, it is heated to a temp close to ..... A....... and grains obtained after cooling are........ B.........
A. Lower critical temp/ upper critical temp
B. Fine / coarser

If the elongation factor during rolling of an ingot is $$1.22.$$ The minimum number of passes needed to produce a section $$250 \times 250\,\,mm$$ from an ingot of $$750 \times 750\,\,mm$$ are

In a single pass flat rolling operation, a $$400mm$$ wide steel strip having a thickness of $$10mm$$ is reduced to $$8mm$$ by using a roll of $$600mm$$ diameter.

The roll-strip contact length is

In a single pass flat rolling operation, a $$400$$ $$mm$$ wide steel strip having a thickness of $$10mm$$ is reduced to $$8$$ $$mm$$ by using a roll of $$600mm$$ diameter.

Considering the situation for a maximum draft of the process, what is the coefficient of friction?

Calculate the minimum number of hot rolling passes necessary to reduce an ingot of $$200mm$$ thickness to $$100mm$$ thickness in two high reversible rolling mill with roll diameter is $$500$$ $$mm.$$ The coefficient of friction between the rolls and the hot material is assumed as $$0.20.$$

A steel wire of length $$100$$ $$m$$ and diameter $$12.214$$ $$mm$$ is drawn to a final diameter of $$10mm.$$ Tensile tests of specimen made before and after the drawing operation gave yield stress as $$200$$ $$MPa$$ and $$400$$ $$MPa$$ respectively,

The yield stress of the steel at a true stain $$0.2,$$ by assuming linear strain hardening law.

A steel wire of length $$100$$ $$m$$ and diameter $$12.214$$ $$mm$$ is drawn to a final diameter of $$10mm.$$ Tensile tests of specimen made before and after the drawing operation gave yield stress as $$200$$ $$MPa$$ and $$400$$ $$MPa$$ respectively,

The length of drawn wire is

In a wire drawing operation diameter of $$6mm$$ is reduced in stages to a diameter of $$1.34mm.$$ Assuming ideally rigid plastic material and ideally lubricant condition,
$$i)$$$$\,\,\,\,\,\,\,$$ The minimum number of passes required by assuming max reduction per pass
$$\,\,\,\,\,\,\,\,\,\,\,\,$$ is obtained with $$\mu = 0.2$$ and half die angle as $${6^0}$$. If the flow strength of the
$$\,\,\,\,\,\,\,\,\,\,\,\,$$ material is $$60$$ $$MPa.$$

$$ii)$$$$\,\,\,\,\,$$ The diameter of wire after $${2^{nd}}$$ stage