H
Half Hard Temper
(A) No. 2 Temper. In low carbon cold-rolled strip steel, produced by cold rolling to a hardness next to but somewhat softer than full hard temper. (B) In brass Stainless Steel Strip, tempers are based on minimum tensile or yield strength. For Chromium-Nickel grades Half-Hard Temper 150,000 TS., 110,000 YS. Min.
Hammer Forging
Forging in which the work is deformed by repeated blows.
Compare with press forging.
Hard Drawing
Drawing metal wire through a die to reduce cross section and increase tensile strength.
Hard Drawn
Wire or tubing drawn to high tensile strength by a high degree of cold work.
Hard Drawn Spring Steel Wire
A medium high carbon cold drawn spring steel wire. Used principally for cold springs.
Hardenability
The ability of a metal, usually steel, to harden in depth as distinguished from the terms “hardness.”
Hardened & Tempered Spring Steel Strip
A medium or high carbon quality steel strip which has been subjected to the sequence of heating, quenching and tempering.
Hardness
Degree to which a metal will resist cutting, abrasion,
penetration, bending and stretching. The indicated hardness of
metals will differ somewhat with the specific apparatus
measuring hardness. (See Brinell Hardness, Rockwell Hardness,
Vickers Hardness, Scleroscope Hardness) Tensile Strength also
is an indication of hardness. See Heads
(Dished) for more information.
Hard Temper
(A) For Steel see Full Hard Temper.
(B) In brass mill terminology. Hard Temper is four B & S numbers hard or 37.1 % reduction.
Hardening
Process that increases the hardness of steel,
i.e., the degree to which steel will resist cutting, abrasion,
penetration, bending, and stretching.
WHY
The increased endurance provided by hardening makes
steel suitable for additional applications.
HOW
Hardening can be achieved through various methods,
including (1) heat treatment, where the properties of steel
are altered by subjecting the steel to a series of temperature
changes; and (2) cold working, in which changes in the
structure and shape of steel are achieved through rolling,
hammering, or stretching the steel at a relatively low
temperature.
Heat (of steel)
A batch of refined steel. A basic oxygen or electric furnace
full of steel. One heat of steel will be used to cast several
slabs, blooms or billets.
Heat Number
The identification that describes the origin of the slab
(heat).
Heat Tinting
Coloration of a metal surface through oxidation by heating
to reveal details of structure.
Heat Treatment
- WHAT
Altering the properties of steel by subjecting it
to a series of temperature changes.
- WHY
To increase the hardness, strength, or ductility of
steel so that it is suitable for additional applications.
- HOW
The steel is heated and then cooled as necessary to
provide changes in the structural form that will impart the
desired characteristics. The time spent at each temperature
and the rates of cooling have significant impact on the effect
of the treatment.
Heat affected zone (HAZ)
The part of the parent metal which is metallurgically
affected by the heat of welding or thermal cutting but not
melted. (Also known as the zone of thermal disturbance).
Heavy Structural Shapes
A general term given to rolled flanged sections that have at
least one dimension of their cross sections three inches or
greater. The category includes beams, channels, tees and zees
if the depth dimension is three inches or greater, and angles
if the length of the leg is three inches or greater.
Hematite
The oxide of iron of highest valency which has a composition
close to the stoichiometric composition Fe2O3.
High Brass
65% - A copper-zinc alloy containing 35% zinc. Possesses high tensile strength and is used for springs, screws, rivets, etc.
High-Carbon Steel
Steel with more than 0.3% carbon. The more carbon that is
dissolved in the iron, the less formable and the tougher the
steel becomes. High-carbon steel's hardness makes it suitable
for plow blades, shovels, bedsprings, cutting edges, or other
high-wear applications.
High Strength
Product intended for
applications where greater strength is critical. High
Strength typically begins at 35 ksi minimum yield strength.
High Strength Low Alloy
(HSLA)
A specific group of steels
in which the strength levels are achieved by the addition of
moderate amounts of alloying elements. The most common are
columbium, vanadium or titanium.
High Temperature
Hydrogen Attack
A loss of strength and malleability of steel due to high
temperature reactions of absorbed hydrogen with carbides in
the steel, resulting in decarburisation and internal
fissuring.
Hollow Structural
Sections
A high-strength, cold-formed steel tubing used in used for
structural purposes in a broad range of applications. Its
biggest advantage is the high strength-to-weight ratio it
possesses.
Homogenizing
Holding at high temperature to eliminate or decrease
chemical segregation by diffusion.
Homogenizing Annealing
An annealing treatment carried out at a high temperature,
approaching the solidus temperature, for a sufficiently long
time that inhomogeneous distributions of alloying elements
are reduced by diffusional processes.
Hooke’s Law
Stress is proportional to strain in the elastic range. The value of the stress at which a material ceases to obey Hooke’s law is known as the elastic limit.
Hose protector
A small non-return valve fitted to the blow-pipe end of a hose
to resist the retrogressive force of a flashback.
Hot Band (Hot-Rolled Steel)
A coil of steel rolled on a hot-strip mill (hot-rolled steel).
It can be sold in this form to customers or further processed
into other finished products.
Hot Briquetted Iron (HBI)
Direct reduced iron that has been processed into briquettes.
Instead of using a blast furnace, the oxygen is removed from
the ore using natural gas and results in a substance that is
90%-92% iron. Because DRI may spontaneously combust during
transportation, HBI is preferred when the metallic material
must be stored or moved.
Hot Dip
In steel mill practice, a process whereby ferrous alloy base metals are dipped into molten metal, usually zinc, tin or terne, for the purpose of fixing a rust resistant coating.
Hot End
The section of a steelmaking complex from the furnace up to,
but not including, the hot-strip mill.
Hot Metal
The name for the molten iron produced in a blast furnace. It
proceeds to the basic oxygen furnace in molten form or is cast
as pig iron.
Hot Rolled Sheet
Steel sheet that is
processed to its final thickness by rolling at high
temperatures on a specially designed hot-rolling facility.
Also commonly known as hot rolled unprocessed.
Hot Rolled Sheet
Non-Temper Rolled
A U. S. Steel definition
for product supplied as a coil directly off the Hot Strip
Mill with no additional processing.
Hot Rolled Sheet Pickled
A U. S. Steel definition
for a mill edge coil that is pickled, oiled and temper
rolled with coil ends cropped back to meet gauge tolerances.
Hot Rolled Sheet Pickled
Non-Temper Rolled
A U. S. Steel definition
for a mill edge coil that is pickled and oiled with coil
ends cropped back to meet gauge tolerances.
Hot Rolled Sheet
Products
Flat steel products that
are brought to final thickness by rolling through a Hot
Strip Mill at high temperatures.
Hot Short
Brittleness in hot metal.
Hot-Strip Mill
A rolling mill of several stands of rolls that converts slabs
into hot-rolled coils. The hot-strip mill squeezes slabs,
which can range in thickness from 2-10 inches, depending on
the type of continuous caster, between horizontal rolls with a
progressively smaller space between them (while vertical rolls
govern the width) to produce a coil of flat-rolled steel about
a quarter-inch in thickness and a quarter mile in length.
Hot Top
(See Sinkhead)
Hot Working
Plastic deformation of metal at a temperature sufficiently high not to create strain hardening. The lower limit of temperature for this process is the re-crystallization temperature.
Hydroforming
A forming process in which a tube is placed into a forming
die. The tube is then formed to the shape of the die through
the application of internal water pressure. The hydroforming process allows for severe shape
deformation, making it ideal for automotive structural parts
such as engine cradles, radiator supports and body rails.
Various shaped and sized holes can be punched in the tube
almost anywhere during the process.
Hydrogen Embrittlement
(1) Brittleness of metal, resulting from the occlusion of hydrogen (usually as a by-product of pickling or by co-deposition in electroplating).
(2) A condition of low ductility resulting from hydrogen absorption and internal pressure developed subsequently. Electrolytic copper exhibits similar results when exposed to reducing atmosphere at elevated temperature.
Hydrogen-Induced Cracking
Stepwise internal cracks that connect adjacent hydrogen
blisters on different planes in the metal, or to the metal
surface.
Hydrogen Stress Cracking
Cracking of a metal resulting from the combination of hydrogen
and tensile stress.
Hypereutectoid Steel
A steel having more than the eutectoid percentage of carbon. (See Eutectoid
Steel)
Hupoeutectoid Steel
Steel with less than eutectoid percentage of carbon. (See Eutectoid
Steel)
HYL I, HYL III
Processes for producing DRI and HBI developed by Hylsa. The
processes reduce iron ore lump or pellets with reformed
natural gas in a vertical shaft furnace. The HYL I process
uses four fixed-bed reactors; HYL III uses a single-shaft
furnace.
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