Materials for machining, fabrication and molding

Aluminum alloys

Light, machinable and corrosion-resistant; the default for machined prototypes, enclosures and structures.

• 6061 Aluminum

  6061 is the general-purpose aluminum alloy: strong enough for structure, easy to machine, weldable, corrosion-resistant and stocked in every form. Values for T6.

• 7075 Aluminum

  7075 is the high-strength aerospace aluminum: 572 MPa (83 ksi) tensile in T6, machines superbly, but is not weldable and stress-corrosion prone. Values for T6.

• 5052 Aluminum

  5052 is the sheet metal aluminum: the easiest common alloy to bend, weldable without losing much strength, and excellent in salt water. Values for H32.

• 6063 Aluminum

  6063 is the architectural extrusion alloy: intricate thin-wall profiles, the best anodized finish of the common alloys, at 75% of 6061 strength. Values for T6.

• 2024 Aluminum

  2024 is the aircraft aluminum: strong, with the best fatigue and crack tolerance of the common alloys, but corrodes bare and cannot be welded. Values for T3.

• 5083 Aluminum

  5083 is the marine plate alloy: the strongest common non-heat-treatable aluminum, welds without losing much strength, and resists seawater. Values for H116/H321.

• 7050 Aluminum

  7050 is the thick-plate aerospace alloy: near-7075 strength held through 150 mm (6") sections, with far better stress-corrosion resistance. Values for T7451.

• MIC-6 Cast Aluminum Tooling Plate

  MIC-6 is cast aluminum tooling plate: stress-free, flat and finished on both faces, for fixtures, bases and jigs. Low strength; not for cosmetic anodizing.

Carbon steels

Inexpensive, weldable and everywhere: mild steel for structure and general parts, medium-carbon for shafts.

• 1018 Steel

  1018 is the default low-carbon machining and welding steel: cold-drawn bar with a clean finish, good machinability, easy welding and a carburizable surface. Values for cold drawn.

• 1045 Steel

  1045 is the medium-carbon workhorse for shafts and machine parts: stronger than 1018, induction- or flame-hardenable to 55-60 HRC, still machinable and affordable. Values for cold drawn.

• A36 Steel

  A36 is the everyday structural steel: hot-rolled plate, angle, channel and beam with a 250 MPa (36 ksi) minimum yield, cut, formed and welded by every fab shop in the U.S.

• 12L14 Steel

  12L14 is the fastest-machining carbon steel: lead, sulfur and phosphorus give short chips and mirror finishes for screw-machine parts. Not weldable, not for hardening.

• A572 Grade 50 Steel

  A572 Grade 50 is the high-strength structural steel: 345 MPa (50 ksi) minimum yield from a columbium-vanadium microalloy, fabricated like A36 at a small premium.

• 1095 Steel

  1095 is the classic high-carbon steel for blades, springs and wear parts: cheap, easy to harden to 58-62 HRC, and available as annealed strip or blade stock. Values for annealed and hardened.

Alloy steels

Chromium, molybdenum and nickel additions that heat treat to high strength, toughness and wear resistance.

• 4140 Steel

  4140 is the go-to Cr-Mo alloy steel: stocked annealed or pre-hard at 28-32 HRC, it through-hardens and nitrides well. Values annealed and Q&T.

• 4340 Steel

  4340 is the Ni-Cr-Mo steel for heavy, highly stressed parts: it hardens through thick sections and stays tough at high strength. Values Q&T and annealed.

• 4130 Steel

  4130 chromoly is the weldable Cr-Mo steel for tube frames, roll cages and aircraft structure: strong when normalized, TIG welds cleanly. Values normalized.

• 8620 Steel

  8620 is the standard carburizing steel: machined soft, then carburized to a 58-63 HRC case over a tough core. Values annealed and carburized.

• 52100 Steel

  52100 is the classic bearing steel: 1% carbon, 1.5% chromium, through-hardened to 58-64 HRC for balls, rings and rollers. Values annealed and hardened.

Tool steels

Hardenable steels for dies, punches, molds and cutting tools, chosen by wear, toughness and hot hardness.

• D2 Tool Steel

  D2 is the high-carbon, high-chromium cold work tool steel: top wear resistance for blanking dies, punches and slitter knives at 58-62 HRC.

• A2 Tool Steel

  A2 is the air-hardening, 5% chromium cold work tool steel: tougher than D2, stable in heat treatment, hardened to 57-62 HRC for dies, punches and gauges.

• O1 Tool Steel

  O1 is the oil-hardening general-purpose tool steel: cheap, easy to machine, hardens to 57-62 HRC, stocked everywhere as drill rod and ground flat stock.

• H13 Tool Steel

  H13 is the 5% chromium hot work tool steel for die casting, extrusion and forging dies: tough and heat-check resistant at 44-52 HRC, and often nitrided.

• S7 Tool Steel

  S7 is the shock-resisting tool steel: the toughest common tool steel at 54-58 HRC, for chisels, punches, shear blades and tools that take repeated impact.

• M2 High-Speed Tool Steel

  M2 is the general-purpose high-speed steel: 60-65 HRC with red hardness, for drills, taps, end mills, broaches and wear-resistant punches.

Stainless steels

Chromium-bearing steels that resist corrosion: austenitic, martensitic, precipitation-hardening and duplex grades.

• 303 Stainless Steel

  303 is 304 with sulfur added for machinability: the stainless to run on a screw machine. It welds poorly and needs careful passivation. Values for annealed bar.

• 304 Stainless Steel

  304 is the workhorse 18-8 austenitic stainless: weldable, formable, corrosion-resistant and stocked in every form. Use 304L for welded work. Values annealed.

• 316 Stainless Steel

  316 is 304 with 2-3% molybdenum: the marine and chemical-service austenitic stainless, with far better chloride pitting resistance. 316L for welds. Values annealed.

• 17-4 PH Stainless Steel

  17-4 PH is the most used precipitation-hardening stainless: machine it soft, then age it at 480-620 °C to 28-47 HRC with almost no distortion. Corrosion near 304.

• 15-5 PH Stainless Steel

  15-5 PH is the remelted, ferrite-free cousin of 17-4 PH: the same strength and aging cycles with better toughness across the grain. Chosen for forgings and thick sections.

• 410 Stainless Steel

  410 is the basic hardenable 12% chromium stainless: cheap, magnetic, quench-and-temper to about 40 HRC, and adequate against mild corrosion. Values annealed and hardened.

• 416 Stainless Steel

  416 is the free-machining martensitic stainless: the easiest stainless to machine at about 85% of B1112, hardenable to about 40 HRC. Bar only; do not weld it.

• 420 Stainless Steel

  420 is the cutlery and mold stainless: 12-14% chromium with enough carbon to harden to 50-54 HRC and hold an edge. Corrosion resistance needs the hardened, polished state.

• 440C Stainless Steel

  440C is the hardest standard stainless: 1% carbon, 17% chromium, 58-60 HRC hardened, for bearings, blades and valve parts. Machine annealed, grind hard. Corrosion modest.

• 2205 Duplex Stainless Steel

  2205 duplex is half austenite, half ferrite: about twice the yield strength of 316 with far better chloride pitting and stress-corrosion resistance. Values solution annealed.

Copper, brass and bronze

Conductivity, machinability and bearing properties: pure copper, free-machining brass and bearing bronzes.

• C360 Free-Cutting Brass

  C360 is the free-cutting brass: 3% lead makes it the 100% machinability benchmark for all metals. Turned fittings, valves and hardware. Not for drinking water. Values H02.

• C260 Cartridge Brass

  C260 is 70/30 cartridge brass, the most ductile common brass: it deep-draws, stamps, spins and takes a bright finish. Sheet and strip for formed parts. Values H02.

• C110 Copper (ETP)

  C110 is electrolytic tough pitch copper, 99.9% pure: the standard for bus bar, conductors and heat sinks at 100% IACS. Soft, formable, hard to machine. Values H02.

• C932 Bearing Bronze (SAE 660)

  C932 (SAE 660) is the general-purpose bearing bronze: 7% tin, 7% lead, cast into bar and bushing stock. Machines at 70% of C360 and runs against steel shafts. As cast.

• C954 Aluminum Bronze

  C954 is cast aluminum bronze: 11% aluminum, 4% iron, about 585 MPa (85 ksi) as cast. Heavy-duty bushings, gears, wear plates and marine parts. As cast.

• C172 Beryllium Copper

  C172 beryllium copper ages to 36-42 HRC with useful conductivity: springs, contacts, bushings, spark-resistant tools. Its dust is toxic. Values TF00.

Titanium alloys

Strength of steel at 56% of the weight, with excellent corrosion resistance and biocompatibility.

• Grade 2 Titanium

  Grade 2 is commercially pure titanium: top corrosion resistance and formability, weldable, 57% of steel's density, near 6061 strength. Values annealed.

• Ti-6Al-4V Titanium (Grade 5)

  Ti-6Al-4V (Grade 5) is the titanium alloy: 895 MPa (130 ksi) tensile at 56% of steel's density, biocompatible, but slow to machine and costly. Values annealed.

Nickel alloys

Superalloys that keep their strength and corrosion resistance at temperatures where steels fail.

• Inconel 718

  Inconel 718 is the workhorse superalloy: 1240 MPa (180 ksi) tensile to 650 °C (1200 °F), weldable, printable, slow to machine. Values solution treated and aged.

• Inconel 625

  Inconel 625 is the corrosion superalloy: 830 MPa (120 ksi) tensile, resists chlorides, acids and oxidation to 980 °C (1800 °F), easy to weld. Values annealed.

• Monel 400

  Monel 400 is the nickel-copper alloy for seawater and hydrofluoric acid: 550 MPa (80 ksi) tensile, ductile, easy to weld and form. Values annealed.

• Hastelloy C-276

  Hastelloy C-276 handles the worst wet chemistry: wet chlorine, bleach, ferric chloride and hot acids. 690 MPa (100 ksi) tensile, welds as-is. Values annealed.

Cast irons

Gray and ductile irons: cheap, damping, castable into complex shapes, and very machinable.

• Gray Cast Iron

  Gray iron is the cheapest metal to cast and machine: high damping, strong in compression, good wear, but brittle and not weldable. Values for A48 Class 30/40.

• Ductile Iron

  Ductile iron is tough cast iron: 448 MPa (65 ksi) tensile, 12% elongation, a true yield strength, cast and machined like gray iron. Values for A536 65-45-12.

Engineering plastics

Machinable and moldable polymers for wear parts, insulators, seals, housings and chemical service.

• Delrin (Acetal)

  Delrin is acetal homopolymer: the stiffest, most machinable general-purpose plastic, with low friction and good fatigue life. Values for natural extruded stock.

• Nylon 6/6

  Nylon 6/6 is the tough, wear-resistant workhorse plastic for gears, bushings and molded housings. Strong and cheap, but it absorbs water and grows. Values dry as molded.

• PEEK

  PEEK is the top-of-the-range machinable thermoplastic: strong to 250 °C, chemically inert, steam-sterilizable and implantable, at a premium price. Values for unfilled stock.

• Ultem (PEI)

  Ultem (PEI) is an amber, amorphous high-heat plastic: stiff to about 170 °C, inherently flame-resistant, sterilizable, and about half the price of PEEK.

• UHMW Polyethylene (UHMW-PE)

  UHMW polyethylene: the most abrasion-resistant, impact-tough, slippery low-cost plastic, for wear strips, liners and guides. Soft and springy; not precise.

• PTFE (Teflon)

  PTFE (Teflon): the most inert, slipperiest plastic, usable from cryogenic to 260 °C. Soft and weak; it cold flows under load, so bearings use filled grades.

• Polycarbonate (PC)

  Polycarbonate: the tough, clear plastic, with about 30x the notched impact strength of acrylic; cold-bendable, stiff to 130 °C. Scratches; solvents crack it.

• ABS

  ABS is the cheap, tough housing plastic: easy to mold, machine, glue, paint, plate and thermoform. Limited to about 80 °C, with poor UV and solvent resistance.

• HDPE (High-Density Polyethylene)

  HDPE: cheap, chemical-proof, weldable polyethylene for tanks, cutting boards, marine parts and pipe. Soft and weak; it cannot be glued and moves with heat.

• Acrylic (PMMA)

  Acrylic (PMMA): the clear, hard, weatherproof plastic for signs, displays and optics. Laser-cuts and polishes well but is brittle; cast and extruded differ.

• PVC (Rigid, Type 1)

  Type 1 PVC is rigid, unplasticized PVC: cheap, stiff, flame-resistant and acid-proof, for tanks, ducts and piping. Good to about 60 °C; never laser cut it.

• G10 / FR4 (Glass-Epoxy Laminate)

  G10 and FR4 are woven glass-epoxy laminates: stiff, strong, stable electrical insulators; FR4 is flame-retardant. Abrasive to machine; control the dust.

Grade comparisons

Two materials side by side across machining, welding, forming, strength, corrosion, finishing, cost and availability.

Material and process guides

Can it be welded, anodized, hardened, laser cut? Straight answers with what to put on the drawing.