Ferrous Metals 231

AISI-SAE designations

A steel classification system developed by the American Iron and Steel Institute (AISI) and the Society of Automotive Engineers (SAE). AISI-SAE designations are usually four-digit numbers based on a steel's contents.

alloy steel

A steel that contains intentionally added materials that change the property of the metal. Common alloying elements include manganese, molybdenum, and nickel.

austenitic stainless steel

Stainless steel that exhibits high strength and ductility and a unique microstructure. Austenitic stainless steel is the most corrosion resistant.

carbide

A compound developed by the combination of carbon with other elements such as chromium, tungsten, or titanium. Carbide is often used to make metal cutting tools due to its hardness and wear resistance.

carbides

A compound developed by the combination of carbon with other elements such as chromium, tungsten, or titanium. Carbide is often used to make metal cutting tools due to its hardness and wear resistance.

carbon

A common, non-metallic element that is combined with iron to create steel. Carbon content typically increases hardness in metal.

cast

A manufacturing process that pours a liquid material into a hollow mold until the material cools into a solidified shape. Cast iron parts are made through casting methods.

cast irons

An iron alloy usually containing more than 2% carbon, along with silicon and sulfur. Cast iron products are usually made through casting processes.

chromium

A metallic alloying element that increases hardenability and corrosion resistance. Chromium is often used in ferrous alloys such as stainless steel.

chromium oxide

A protective film that develops on the surface of stainless steel. Chromium oxide helps to prevent corrosion.

cold working

Any metal shaping process that takes place when the metal is below its recrystallization temperature. Cold working adds certain properties to the metal, such as increased strength and improved surface finish.

compressive strength

The ability of a metal to resist forces that attempt to squeeze or crush it. Cast irons have good compressive strength.

corrosion resistance

The ability of a material to resist deterioration and chemical breakdown due to surface exposure in a particular environment. Chromium increases the corrosion resistance of ferrous metals.

ductile cast iron

A type of cast iron with a similar composition to gray cast iron, but with improved ductility. Ductile cast iron contains tiny spheres of graphite.

ductility

The measure of a material's ability to be drawn, stretched, or formed without fracturing. Ductility usually decreases when more carbon is added to a ferrous metal.

ferritic stainless steel

Stainless steel that has a low carbon content and a unique microstructure. Ferritic stainless steels are easy to weld but not hardenable by heat treatment.

ferrous metals

A metal in which iron is the main ingredient. The main groups of ferrous metals are cast iron and steel.

free-machining steels

A particular grade of steel that has small amounts of additional alloying elements to improve machinability. Free-machining steels are plain carbon steels.

graphite

A soft, black form of carbon. Excess carbon often appears as graphite flakes in cast irons and helps to dampen vibrations and improve machinability.

gray cast iron

A type of cast iron with high levels of carbon and excellent compressive strength. Gray cast iron is the most common cast iron.

heat treatment

The controlled heating and cooling process used to change the structure of a material and alter its physical and mechanical properties. Annealing, quenching, and tempering are heat treatments.

high-carbon steel

A carbon steel that contains more than 0.6% carbon. High-carbon steels are extremely strong and hard.

high-strength low-alloy steels

HSLA. A type of steel that contains low levels of carbon and alloying elements. High-strength low-alloy steel exhibits good strength and is relatively inexpensive.

hot working

The shaping of metal at temperatures above its recrystallization phase. Hot working typically leaves a tough, scaly surface on the metal.

iron

A silver-white, metallic element that is highly magnetic. Iron is alloyed with carbon to make steel.

low-carbon steel

A carbon steel that contains less than 0.3% carbon. Low-carbon steels are generally tough, ductile, and easily welded.

malleable cast iron

A type of cast iron with a similar composition to white cast iron, but with improved malleability. Malleable cast iron is heat treated.

manganese

A metallic alloying element that increases strength, hardness, and hardenability. Manganese is often used in ferrous alloys to improve impact resistance.

martensitic stainless steel

Stainless steel that is stronger than ferritic stainless steel, but less corrosion resistant. Martensitic stainless steels have a unique microstucture and are hardeneable by heat treatment.

medium-carbon steel

A carbon steel that contains between 0.3% and 0.6% carbon. Medium-carbon steels are strong, hard, and not as easily welded as low-carbon steels.

microstructure

The shape and alignment of the microscopic components of a metal. A material's microstructure determines its hardness, toughness, and other properties.

molybdenum

A metallic alloying element that increases hardenability, strength, and wear resistance. Molybdenum is considered a refractory element and is often used in ferrous alloys.

nickel

A metallic alloying element that increases strength, impact resistance, and corrosion resistance. Nickel is often used in ferrous alloys and as a base metal in superalloys.

plain carbon steel

Steel that contains less than 3% of elements other than iron and carbon. Plain carbon steel is considered the most pure form of steel.

resulfurized and rephosphorized steels

A plain carbon steel that contains added sulfur and phosphorus for improved machinability.

resulfurized steels

A plain carbon steel that contains added sulfur for improved machinability.

silicon

A non-metallic element often found in sand and used to make glass. Silicon is added to metal to improve hot-forming properties.

stainless steel

A type of alloy steel that contains a large percentage of chromium. Stainless steels exhibit excellent corrosion resistance and high strength.

steel

A ferrous metal consisting of iron and carbon, usually with small amounts of manganese, phosphorus, sulfur, and silicon. Steels are classified using AISI-SAE designations.

steels

A ferrous metal consisting of iron and carbon, usually with small amounts of manganese, phosphorus, sulfur, and silicon. Steels are classified using AISI-SAE designations.

superalloys

An expensive metal alloy consisting of numerous alloying elements. Superalloys, or high-performance alloys, are designed to perform under intense conditions.

tensile strength

The ability of a material to resist forces that attempt to pull apart or stretch it. Tensile strength is the amount of tensile stress a material can withstand before fracturing.

tool steels

A specialized type of alloy steel that has excellent strength, toughness, and wear resistance. Tool steels are used in cutting tools, punches, and other industrial tooling.

vanadium

A metallic alloying element that increases strength and creep resistance. Vanadium is often added to ferrous alloys to facilitate the development of carbides.

weldability

The ability of a material to be welded into a suitable structure. HSLA steels exhibit good weldability.

white cast iron

A type of cast iron with lower levels of carbon and improved tensile strength. White cast iron contains little to no graphite.

yield strength

The maximum stress a material can withstand before being plastically deformed. Yield strength is also called the elastic limit.