Materials database

Silicon spring steel — Si (1.5-2.0%) provides high elastic limit and excellent fatigue resistance without expensive Cr/V additions. Better heat resistance than Cr-spring steels — retains spring properties to ~250°C. Used for valve springs, clutch springs, hot-wound coil springs, and applications with moderate elevated temperature exposure. Cheaper than CrV spring steels.

High-carbon chromium-vanadium spring steel — higher C (0.55-0.62%) than 51CrV4 (0.47-0.55%) for maximum hardness and fatigue strength. V refines grain and improves temper resistance. Used for the most demanding spring applications: heavy-duty coil springs, torsion bars, stabilizer bars, and spring tools. Also used as tool steel (1.2242/59CrV4 variant).

Silicon-chromium valve spring steel — the highest fatigue life among EN 10089 spring steels. High Si (1.50-1.80%) provides excellent resistance to relaxation at elevated temperatures (up to ~250°C). Superior to 51CrV4 for high-stress, high-cycle applications. Used for automotive valve springs, heavy-duty coil springs, torsion bars, and stabilizers. ≈ AISI 9260.

Nickel-chromium-molybdenum case-hardening steel. Good combination of core toughness and case hardness. The most widely used case-hardening steel in the US (AISI 8620). Used for gears, pinions, worm drives, king pins, and cross-shafts.

Free-cutting steel with high sulfur for excellent machinability. Very similar to 11SMn30 — historical German designation that is still widely referenced. Lower C variant preferred for some screw machine products. Used for high-volume automatic lathe parts, screws, nuts, pins, and bushings. ≈ AISI 1215.

Leaded free-cutting steel — Pb (0.15-0.35%) + S (0.24-0.33%) for maximum machinability. THE ultimate Automatenstahl: machinability rating ~175% (vs 100% for 11SMn30). Pb acts as chip-breaker and tool lubricant. Used for high-speed automatic screw machine production of screws, nuts, fittings, bushings, and any part where surface finish and cycle time matter most. NOTE: Pb content being phased out under EU ELV/RoHS — replacement grades emerging.

Cr-Mo quench-and-temper alloy steel — the lower-carbon version of 4140 (42CrMo4). Lower C (0.33-0.38%) gives better weldability and toughness than 4140 with slightly lower strength. Primarily a US/ASTM designation. Used for drill pipe, tubing, couplings, and oil field applications where weldability matters more than maximum strength.

The most common structural carbon steel in the US. Low carbon content with good weldability and machinability. Used for buildings, bridges, construction equipment, and general structural purposes. Minimum yield strength 36 ksi (250 MPa).

The most widely used structural steel grade in the United States. 345 MPa (50 ksi) yield strength HSLA steel. Has largely replaced A36 for structural applications due to higher strength-to-weight ratio. Used for building frames, bridges, heavy equipment, and general structural fabrication.

High-strength low-alloy weathering steel. Forms a stable protective rust patina eliminating the need for paint. Cu-Cr-Ni-V composition provides 4-8x atmospheric corrosion resistance vs carbon steel. Used for unpainted bridges, architectural facades, sculptures, outdoor structures, and freight cars.

Low-carbon unalloyed steel. Excellent weldability, good formability, and low hardness. Used for pins, rivets, bushings, case-hardened parts with thin case depth, and general cold-formed components. Can be case-hardened for surface wear resistance.

Highest-carbon unalloyed spring/tool steel — C 0.95-1.05%. Maximum hardness (HRC 63-66) in the unalloyed range. On the boundary between spring steel and tool steel. Used for flat springs requiring absolute maximum hardness, doctor blades, cutting tools, cold stamping dies, and wood-working saw blades. Also known as Silberstahl (silver steel) in wire form.

Lowest practical carbon case-hardening steel — 0.07-0.13% C. After carburizing: hard surface (HRC 55-60) with extremely soft, tough core (HRC 15-20). Maximum impact absorption. Modern designation for Ck10. Used for pins, bushings, small gears, camshaft lobes, and any carburized part where maximum core toughness and ductility are critical. Also used as cold-heading and deep-drawing wire/strip.

Low-carbon unalloyed case-hardening steel. The simplest and most economical case-hardening grade. Used for lightly loaded gears, pins, bushings, rivets, and small machine parts where a hard wear-resistant surface with a soft tough core is needed.

Low-carbon unalloyed case hardening steel — 0.12-0.18% C. Between C10E (softer core) and C22E (harder core) in the case-hardening range. Good balance of surface hardness (HRC 58-62) and core toughness after carburizing. Modern designation for Ck15. Used for small gears, pins, bushings, levers, and carburized parts where moderate core strength is acceptable. Also used for cold forming and deep drawing.

Low-carbon unalloyed steel for case hardening (carburizing). 0.17-0.23% C gives a tough core with a hard, wear-resistant surface after carburizing + quenching. The simplest and cheapest case-hardening steel. Used for pins, bushings, cam followers, light-duty gears, and general machine parts where a hard surface with tough core is needed. ≈ AISI 1020.

Low-medium carbon unalloyed steel. Good balance of strength, weldability, and formability. Used for lightly loaded shafts, bolts, levers, and general machine parts. Can be case-hardened for wear applications. Between C10 and C35 in properties.

Low-carbon unalloyed steel for case hardening and general engineering — 0.17-0.24% C. After carburizing: surface HRC 55-60, soft tough core. Much cheaper than alloy case-hardening steels (16MnCr5, 20MnCr5). Modern designation for Ck22. Used for pins, bolts, levers, lightly loaded gears, and any carburized part where alloy additions are not justified. Also used as cold-heading wire.

Unalloyed special steel with controlled sulfur (R grade, S 0.020–0.040%) and ~0.22% carbon for improved machinability. Same base composition as C22E but with intentional sulfur for better chip formation. Good weldability and formability. Used for automatically machined low-stress components, bolts, pins, and bushings.

Medium-carbon unalloyed quality steel with 0.22–0.29% carbon. Good machinability and moderate strength in normalized condition. Standard P and S limits (less pure than C25E). Used for bolts, nuts, levers, shafts, and general machine parts not requiring high strength. Can be surface-hardened by induction or flame hardening.

Unalloyed special steel with controlled chemistry (E grade) and ~0.25% carbon. Tighter P and S limits (max 0.025%) than standard C25 for improved consistency. Suitable for quenching and tempering to moderate strength levels. Good machinability and weldability. Used for shafts, bolts, transmission parts, crankshafts, and machine components of moderate stress.

Medium-carbon unalloyed steel with approximately 0.30% carbon. Intermediate strength between C25 and C35. Good machinability and moderate weldability (preheating recommended for thicker sections). Used for moderately stressed structural parts, shafts, bolts, levers, and connecting rods in general mechanical engineering.

Mid-carbon unalloyed Q&T steel — 0.27-0.34% C. Between C22E and C35E — good weldability with moderate strength after Q&T. Modern designation for Ck30. Used for lightly loaded shafts, levers, bolts, and machine parts.

Unalloyed special steel with controlled sulfur (R grade, S 0.020–0.040%) and ~0.30% carbon for improved machinability. Same base composition as C30E but with intentional sulfur for better chip formation. Intermediate strength. Used for automatically machined shafts, bolts, levers, and moderately stressed machine parts.