Alloy Steels Steels alloyed with molybdenum, nickel and chromium (AISI 4037,4130, 8630) are best where high strength is required. These steels have good cold-forming properties in the annealed condition. Can be heat treated for the best combination of strength, toughness and shock resistance.
Aluminum Alloys Good cold-forming characteristics. Many aluminums can be used. (2024, 3003, MM, MM, 6061, 7075) Grade 2011 has excellent secondary machining properties. Aluminum is corrosion resistant and some can be heat treated.
Carbon Steels Fine grain, fully-killed basic steel with no alloying agent.
Low carbon steel range from .06-.1 8% carbon content (AS 1006-1018) and have good ductility for cold forming.
Medium carbon steel have .1 8-.50% carbon content (AJSI 1018, 1038, 1041). Stronger and less ductile, these steels
respond well to quench and temper.
High carbon steels .50% carbon and up (AISI 1066,1095). Difficult to cold form unless annealed. High strength, can be heat
treated.
Hard drawn MB Spring Wire, ASTM A227 Carbon range .60-.70%. Used for general purpose low-cost spring. Commonly available in diameters .031 to .500. Lower tensile strength than music wire.
Leaded Steels Lead added to steel improves machinability. Identified by an "L", (AIS112 14) in the AISJ/SAE designation, is most commonly added to llO0 and 1200 series 'screw machine' steels. Leaded steels are not suitable for treatment or welding.
Music Wire ASTM A228 Carbon range .80- 95%. High tensile strength can withstand repeated loading. Widely used in small diameter rounds .005 to .125.
Resulphurized and Rephosphorized Steels (AISI 1117 and 121S) have improved machinability over basic carbon steels. Used commonly for screw machine parts, they are more brittle, less ductile and stronger than equivalent carbon content basic steel. Sulfur acts as an internal lubricant and is the major alloying agent for "1100" series steels. Phosphorus makes the steel more brittle, reducing friction, heat and tool wear "1200" series steels have both phosphorous and sulfur as alloys.
Stainless Steels (AISI202,302,304,316) are generally nonmagnetic and the most corrosion resistant due to their large content of nickel and chromium. Good cold-forming characteristics are subject to work hardening and are not heat treatable.
Austenitic stainless steel is a straight chromium steel with little or no nickel (AISA 410,420). These steels are magnetic and can be heat treated. Lower corrosion resistance and harder to cold form.
Precipitation Hardening Stainless (AISI 17-4PH) is a nickel chromium stainless with cobalt and tantalum. The alloying
agents produce high strength and ductility, good machinability and weldability. Hardens by aging the cold steel at 900' F for 4 hours followed by air cooling. Not used for cold forming but commonly used for high-strength, corrosion resistant screw
machine parts.
Cold working Deformation of a metal at room temperature without fracture which changes its shape and produces higher tensile strength and machinability.
Ductility The ability of a metal to be deformed extensively under tension load without rupture or fracture. Ductility is expressed in terms of percent elongation and percent reduction of area (e.g. drawn into wire).
Machinability The condition or property of a metal which allows it to be cut, turned, broached or formed by machine tools.
Malleability The ability of a metal to be deformed permanently under compression load without rupture or fracture (e.g. hammer or rolled into sheets.
Tensile strength The maximum load in tension (pulling apart or shearing) which a material can withstand before breaking or fracturing. Also known as the ultimate tensile strength (UTS) or maximum strength.
Work hardening Hardening that takes place through grain alignment when a metal is bent, rolled or hammered at room temperature. Not all metals work harden.
Yield Strength The maximum load at which a material exhibits a specific permanent deformation. Deformation to determine yield varies with material.
Alloy Steel A carbon steel to which one or more elements are added to add special properties for a specific use.
Billet A cast section of steel rolled to 4 to 6 inches square about 20 ft. long from which dimensional shapes of steel are rolled.
Brass An alloy of copper and zinc which can contain small amounts of aluminum, iron, manganese or tin to produce specific properties.
Bronze An alloy of copper and tin or an alloy of aluminum and silicon.
Carbon Steel A steel in which carbon is the only alloying element added to iron.
Killed Steels Molten steel treated with aluminum, silicon, or manganese until no more gas is in the metal and it is in a quiet state.
Pickling The removal of oxide scale from metal by dipping it in a diluted acid bath. The chemically clean surface is then ready for cold rolling or wire drawing.
Rockwell Hardness Test A method of determining metal hardness by indenting with a metal ball or diamond cone under a specified load.
Annealing Heating and slow cooling to remove stresses, make steel softer, refine the structure, or change its ductility.
Carburizing Adding carbon to the surface of iron-based alloys by heating the metal below its melting point in contact with carbon-rich solids, liquids or gases.
Case Hardening Carburizing a metal surface followed by quenching to fix a hard outer case in carbon combined with a relatively soft middle or core.
Cyanide Hardening A method of case hardening which brings the metal surface in contact with the molten cyanide salt followed by a quenching.
Decarburization Removal of carbon from the surface of steel. This can occur through normal oxidizing action or as the result of heat treatment.
Drawing (Tempering) Reheating after hardening , held at a specific temperature and then quenched. This reduces hardening and increases toughness.
Hydrogen Embrittlement A condition where the surface finishing of metal (plating) results in a brittle outer case due to immersion in acid. Baking immediately following the plating process removes this brittle surface condition.
Nitriding A hardening process which adds nitrogen to a metal surface through contact with ammonia gas. Produces surface hardness (case) without quenching.
Precipitation Hardening A hardening process where certain metals are held at elevated temperature without quenching (age hardening).
Quenching Rapid cooling of steel by immersion in oil or water to fix its structure in a hardened state.
Sphereoidizing (anneal) Any process of heating and cooling steel that produces a rounded or globular form of carbide. This softens the metal, improving ductility.
Stress Relieve A low temperature heat treatment which removes stresses caused by cold working.
Aluminum Al
Carbon C
Chromium Cr
Cobalt Co
Copper Cu
Manganese Mn
Molybdenum Mo
Nickel Ni
Phosphorus P
Silicon Si
Tungsten W
Vanadium V
Chemistry of
Element
Carbon
Phosphorus
Sulfur
Manganese
Silicon
Steel
.05-1.5%
.04 Max.
.05 Max.
.30-.90
.15-.30
Cast Iron
2.2-3.8%
.10-1.00
.09-.12
.40-1.00
.50-3.00
The technical material presented in this appendix is for general reference only. Every attempt has been made to ensure the accuracy thereof; however, Pivot Point does not warrant in any way the accuracy or completeness of the information presented. It is the sole responsibility of the user to determine material and design suitability for their specific application.
