Working with a rabble, that is, the tool provided for stirring the molten
metal bath in a puddling furnace with cinder to assist purification.
A series of grooves usually horizontal, made in the surface of a roll in
order to assist the roll to bite the steel and to prevent skidding between
the roll and the work. Ragging is usually found in roughing and forming
Rare Earth Metals
The lanthanide metals of the periodic table (atomic nos. 57 to 71) are also
known as rare earth metals.
The removal of the ragged inside edge at the ends of cut tubes.
The adjustment of carbon content of molten steel by addition of
carbonaceous material, high-carbon pig iron or a high-carbon alloy.
1. A change from one crystal structure to another, such as that occurring
upon heating or cooling through a critical temperature.
2. Formation of a new, strain-free grain structure from the structure
existing in cold-worked metal.
Recrystallization Annealing
Annealing cold-worked metal to produce a new grain structure without a
phase change.
Recrystallization Temperature
The approximate minimum temperature at which recrystallization of a
cold-worked metal occurs within a specified time.
The waste flue gases from high temperature processes contain the sensible
heat of vapourisation of water (apart from the latent heat, which is not
practical to recover) which is recovered in a recuperator by transfer of
heat continuously from one fluid to another.
Red Hardness
The relatively high hardness retained by certain special steels (for
example, high speed tool steels) even when heated up to a low red heat.
Red Rust
A reddish brittle coating of iron oxide which develops on an uncoated or
coated steel surface when oxygen in the atmosphere mixes with iron.
Reducing Agent
Either natural gas or coal can be used to remove the oxygen from iron ore
in order to produce a scrap substitute. In gas-based processes, the iron
ore is heated in a vessel as reformed natural gas passes through. In
coal-based processes, iron ore is combined with gasified or ground coal and
heated. The oxygen in the ore combines with carbon and hydrogen in the gas
or coal, producing reduced, or metallic, iron.
An internal discontinuity originating from a subcutaneous blow-hole which
has become oxidised and has been elongated during rolling.
Reel Breaks
Fractured base metal normally caused by poor leveling. It is indicated by
light kinks across the width of the winding coil.
Ingot mould dressing with soot deposition, derived from tar burning.
Straightening (and planishing) a round bar by feeding it between contoured
steel rolls in a direction approximately parallel to the principal axis of
the rolls.
The removal, by slag or other reactions, of undesirable elements and of
metallic oxides and gases from molten steel.
Refining Slag
The finishing slag employed for refining the heat.
Refractory Brick
Heat-resistant (normally non-metallic) brick. Because its melting point is
well above the operating temperatures of the process, refractory bricks
line most steel making vessels that come in contact with molten metal and
slag, like the walls of the blast furnace, sides of the ladles, and inside
of the BOF apart from the flues or stacks through which hot gases are
conducted. These are made of materials such as dolomite (double calcium and
magnesium carbonate), magnesite (magnesium carbonate), silica (SiO2),
silicates of aluminium, chromic oxides, etc. and are able to withstand
temperatures from 260o to 1760oC.
Reflowed Surface
A shiny tin plate product surface which is achieved by heating the tin
coating up to its melting point (thereby melting the tin) and cooling it
back to room temperature.
Refractory Creep
Like most structural materials, refractories experience creep behaviour
when exposed to high temperatures. Most refractories show two
characteristic stages of creep. In the first stage, called primary creep,
rate of subsidence declines gradually with time. In the second stage,
called steady stage, the rate of subsidence is constant. At very high
temperatures, steady stage creep is sometimes followed by tertiary creep
region where the rate of subsidence accelerates and leads to catastrophic
failure or creep rupture. Primary creep is generally short in duration,
while secondary creep can occur over a long term.
Arrangement (chambers filled with a checkwork of refractory bricks) for
receiving and then utilizing heat from hot spent gas from a furnace. They
are used alternately to absorb heat from one fluid and then transfer it to
another fluid.
Heating steel to a uniform temperature in readiness for hot working.
Reheating Furnaces
These are divided into two general classes :
1. Batch Type : Here, the charged material remains in a fixed position on
the hearth until heated to rolling temperature.
2. Continuous Type : Here, the charged material moves through the furnace
and is heated to rolling temperature as it progresses through the furnace.
These include pusher-type, rotary-hearth-type, walking-beam-type,
walking-hearth-type and roller-hearth-type furnaces. 
Reinforcing Bar (Rebar)
A commodity-grade steel used to strengthen concrete in highway and building
The process of replacing the refractory lining of a liquid steel vessel.
Once it wears out, the brick lining of a furnace must be cooled, stripped
and replaced. This maintenance can be significant because a blast furnace
reline may require up to three months to complete.
R Enamel
An unpigmented enamel used to increase resistance to corrosion, or decrease
bleaching effect of tinplate on food can interiors.
Reversion of or addition of phosphorus into steel under steel making
Reshearing (Resquaring)
Shearing sheets to desired finished dimensions with right-angled edges.
The impurities in mini-mill steel as the result of the mix of metals
entering the process dissolved in obsolete scrap. Residuals are key
concerns regarding the mini-mills' recent entry into the flat-rolled
market, where high residuals can leave sheet steel too brittle for customer
The ability of a material to absorb energy when deformed elastically and
return to its original shape upon release of load.
Resistance Heating
Heating of steel by passing current through solid conductors and using the
heat generated as a result of the conductors' inherent resistance to the
flow of current. It can be applied through three methods :
1. The indirect method, in which the steel is heated by radiation and
convection from resistors through which the current is passed.
2. The direct method in which the current is passed directly from a power
source through the metal.
3. The induction method in which the current is induced in the steel by an
induction coil connected to the power supply. 
Neither the indirect nor the direct method of resistance heating is
practical for steel-making operations. However, the induction method is
employed successfully in special steel-melting operations.
Reversing Mill
The stand of rolls used to reduce steel sheet or plate by passing the steel
back and forth between the rolls; the gap between the rolls is reduced
after each pass.
RH Degassing
Ruhrsthal-Heraeus process developed in the early 1960's with the objective
of degassing a ladle of steel without total enclosure of the ladle in a
vacuum chamber. The argon gas is injected into one leg or extension of the
refractory-lined vacuum vessel, which is dipped into the steel containing
ladle. This causes the molten steel from the ladle to rise into the
evacuated chamber with a boiling action that releases gases from the steel
that then flows back into the ladle through the second leg. The
recirculation of steel is continued until the desired degree of degassing
is attained.
A coating defect consisting of a flow mark defect with an appearance
similar to corduroy fabric. Ribbing usually occurs when the flow marks
(ribs), from application on the coater, do not flow out and level the
surface of the coating.
A hump across the width of the surface of the coil.
When molten steel cools to the temperature range in which it begins to
solidify as ingot, the solubility of gases dissolved in the steel decreases
and the excess gases are expelled from the metal. The amount of gases,
chiefly oxygen, dissolved in liquid steel and the amount of gases released
during the solidification determine the type of ingots : killed,
semi-killed, capped and rimmed.
Sometimes, the amount of gases evolved during solidification are so much
that the top ingot surface does not solidify immediately after pouring.
Instead, numerous honeycomb blowholes form very close to the side surface
of the ingot, extending from top to bottom. The evolution of gas causes the
steel to rise after pouring and produces a boiling action that is commonly
called rimming action. This action is stopped by a metal cap secured to the
top of the mould.
Rimming Steel
A steel possessing a rim of purer material (with maximum freedom from
surface blemishes), and is associated with evolution of carbon monoxide gas
occurring due to the interaction of dissolved iron oxide and carbon during
the solidification of low carbon and low manganese steel made under
controlled deoxidation. The composition and extent of the rim can be varied
and, if required, the rimming action can be arrested after sometime.
Rockwell Hardness Test
An indentation hardness test using a calibrated instrument that utilizes
the depth of indentation, under constant load, as a measure of the hardness
of the material. Either a 120o diamond cone with a slightly rounded point,
or a 1/16-or 1/8-inch diameter steel ball is used as the indenter.
Rod (Wire Rod)
Generally round, square, half-round, rectangular or polygonal semi-finished
steel length that is rolled from a billet and coiled for further
processing. Rod is commonly drawn into wire products or used to make bolts
and nails. Rod trains (rolling facilities) can run as fast as 20,000 feet
per minute (more than 200 miles an hour).
Roke (Roak)
A longitudinal surface defect (an elongated fissure) caused by a blow which
is not welded up during rolling and has perforated the surface and become
Rolled Edge
Edge which is finished accurately to desired shape by using rolls at the
Local areas of scale, formed during a previous heating, which has failed to
be eliminated during the rolling operations and has got pressed into the
surface of the stock during rolling.
Roller Levelling (Mangling)
A staggered system of rolls used to flatten the steel without any
appreciable reduction in gauge.
Roller Table
During the complete rolling cycle, the hot steel is transported by
reversible, live rollers in the mill tables, called roller tables. Front
and back roller tables alternately feed and receive the piece during each
pass through the rolling mill, and mechanical units called manipulators
rotate the piece through 90o as required and move it from pass to pass.
Roll Force Cylinder
See A.G.C. Cylinder.
Roll Force Systems
Mill stands place considerable pressure on slabs, blooms and coils to
further process the material. There are two general ways of applying the
force to the steel‹screw and hydraulic systems. 
Screw (Incline Plane) This older method used the basic principle of the
screw to adjust the space between the mill rolls. Because metal touches
metal, these configurations will wear down over time and can cause quality
Hydraulic (Pancake Cylinder) This modern system uses fluid pressure to
rapidly adjust the roll spacing several times per second. These minute,
instantaneous adjustments allow for superior gauge tracking and
higher-quality products.
Roll Forming
1. An operation used in forming sheet. Strips of sheet are passed between
rolls of definite settings that bend the sheet progressively into
structural members of various contours, sometimes called "moulded
2. A process of coiling sheet into open cylinders.
Roll Marks
Periodic surface defects due to some imperfection on the surface of a roll
or due to particles of matter picked up by rolls.
Roll Pass (Pass)
Openings of definite shapes formed between a set of rolls through which hot
steel passes for taking up the given shape or undergoing a desired amount
of reduction in sectional area. This term also applies to a single passage
through a pair of rolls for the purpose of altering the shape and / or
reducing the cross-sectional area.
The rolls control the reduction and shaping of the metal. There are three
parts to a roll; namely, the body, or the part on which the rolling is
done, the necks which support the body and take the rolling pressure, and
the wobblers, where the driving force is applied through loose-fitting
spindles and boxes which together form a sort of ingenious universal
Roll Scale
Oxide of iron which forms on the surface of steel while it is being heated
and rolled. Much of the scale is cracked and loosened during the rolling
operation and may fall off the piece naturally or be blown off by
high-pressure water sprays or other means.
Roughing Stand
The first rolling stand through which metal passes during hot rolling
imparting very high reduction. Once reduced by the roughing stands, the
metal continues on to the finishing stands where smoother rolls with a
smaller gap are used to complete the hot roll process.
The refractory channel through which the molten steel enters the mould.
Rolling Mill
1. Any of the mills in which metal undergoes a rolling process. These
include the Slabbing Mill, Hot Roll Mills, Cold Roll Mills, Single
Reduction Mills, and Double Reduction Mills.
2. Any operating unit that reduces gauge by application of loads through
revolving cylindrical rolls; operation can be hot or cold. The elevated
temperature rolling mill is the Hot Mill and is capable of reducing the
gauge of a slab 92-99%.
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