Materials database

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.

Medium-carbon unalloyed steel with moderate strength. Good machinability and weldability. Used for lightly stressed components like levers, axles, bolts, and general machine parts.

Mid-carbon unalloyed Q&T steel — 0.32-0.39% C. Good balance between strength and toughness/weldability. Modern designation for Ck35. Used for moderately loaded shafts, axles, bolts, connecting rods, and machine parts where C45 would be too hard and C22E too soft. Also suitable for surface hardening (flame/induction) to HRC 50-55.

Unalloyed special steel with controlled sulfur content (R grade, S 0.020–0.040%) for improved machinability. Same base composition as C35E but with intentional sulfur for better chip formation during high-volume turning and milling. Used for automatically machined shafts, bolts, and medium-stressed machine parts.

Medium-carbon unalloyed steel between C35 and C45 in properties. Good balance of strength and machinability. Used for moderately stressed machine parts, shafts, studs, axles, and crankshafts.

Mid-carbon unalloyed Q&T steel — 0.37-0.44% C. Slightly below C45E in carbon content but very similar properties. Modern designation for Ck40. Used for crankshafts, connecting rods, axles, bolts, and machine parts. Suitable for flame/induction hardening to HRC 52-56.

Unalloyed special steel with controlled sulfur (R grade, S 0.020–0.040%) and 0.40% carbon for improved machinability. Same base composition as C40E but with intentional sulfur for better chip formation in automated machining. Used for shafts, bolts, gears, and general machine parts requiring good strength with high production rates.

Medium carbon unalloyed quality steel. Good machinability and moderate strength after heat treatment. Widely used for shafts, spindles, pins, studs, and general machine parts.

Unalloyed special steel with controlled chemistry (E grade) and 0.42–0.50% carbon. Tighter P and S limits than standard C45 for improved consistency. The most widely used medium-carbon steel for quenching and tempering. Good balance of strength (620–850 MPa QT) and toughness. Through-hardening up to ø60mm. Surface hardening by induction to HRC 58. Used for shafts, gears, bolts, connecting rods, crankshafts, and general machine parts.

Unalloyed special steel with controlled sulfur (R grade, S 0.020–0.040%) and 0.45% carbon for improved machinability. Same base composition as C45E but with intentional sulfur for better chip formation. The most popular R-grade carbon steel for high-volume automated machining. Used for axles, bolts, connecting rods, spindles, crankshafts, and general machine parts.