Materials database

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.

Medium-high carbon unalloyed steel between C45 and C55. Good strength and wear resistance after QT. Used for springs, axles, shafts, coupling parts, and machine components where moderate hardness is sufficient without alloy steel cost.

High-carbon unalloyed Q&T steel — 0.47-0.55% C. Higher strength than C45E at the expense of reduced weldability and toughness. Modern designation for Ck50. Suitable for induction hardening to HRC 55-60. Used for heavy-duty shafts, rail wheels, clutch plates, and springs where maximum unalloyed strength is needed. Also used for agricultural equipment and wear parts.

Unalloyed special steel with controlled sulfur (R grade, S 0.020–0.040%) and 0.50% carbon for improved machinability. Same base composition as C50E but with intentional sulfur for better chip formation. Used for high-volume machined components requiring good strength: shafts, gears, spindles, and wear-resistant machine parts.

Medium-high carbon unalloyed steel. Higher strength than C45 with reduced weldability. Used for rail wheels, agricultural equipment, springs, hand tools, and wear-resistant parts. Often used for induction-hardened components.

High-carbon unalloyed Q&T steel — 0.52-0.60% C. Modern designation for Ck55. Good strength after Q&T (UTS 800-950 MPa) and excellent surface hardness after induction hardening (HRC 56-60). Used for rail wheels, crankshafts, heavy-duty shafts, and wear parts.

Unalloyed special steel with controlled sulfur (R grade, S 0.020–0.040%) and 0.55% carbon for improved machinability. Same base composition as C55E but with intentional sulfur for better chip formation. Used for high-volume machined components requiring moderate to high strength: shafts, axles, gears, and wear-resistant machine parts.

High-carbon unalloyed quenching and tempering steel. High hardness and strength after heat treatment but difficult to weld. Used for springs, hand tools (screwdrivers, pliers), agricultural blades, wear parts, and railway components.

Unalloyed special steel with controlled chemistry (E grade) and 0.60% carbon. Tighter P and S limits (max 0.025%) for improved consistency. High hardness achievable after quenching (HRC 55+). Difficult to weld due to high carbon content. Used for wheels, rims, toothed shafts, cylinders, axles, pins, springs, and wear-resistant components in vehicle and machinery manufacturing.

Unalloyed special steel with controlled sulfur (R grade, S 0.020–0.040%) and 0.60% carbon for improved machinability. Same base composition as C60E but with intentional sulfur for better chip formation. Higher strength than C50R. Used for springs, shafts, rail components, and wear-resistant parts requiring combined strength and machinability.

Medium-high carbon spring steel — C 0.65-0.72%. The E suffix denotes controlled S+P (<=0.025% each). Used for cold-rolled spring strip (EN 10132-4), spring wire (EN 10270-1), and flat springs. Lower C than C75S/C85S = better toughness and formability. Also used for circular saw blades, scrapers, and clips. Hardened & tempered to HRC 55-60.

Unalloyed cold-rolled spring strip steel — THE standard flat spring material. 0.65% C gives high hardness after hardening (HRC 60+). Very good fatigue properties when properly heat-treated. Much cheaper than alloyed spring steels (51CrV4, 55Cr3). Used for flat springs, circlips/snap rings, saw blades, scrapers, reed valves, and leaf springs in small dimensions.

High-carbon unalloyed steel for springs and cutting tools with 0.65–0.75% carbon. Good combination of hardness and toughness compared to higher-carbon grades. Used for coil springs, leaf springs, saw blades, chisels, and shear blades. Can achieve 50–56 HRC after proper heat treatment. The S suffix indicates suitability for spring applications per EN 10132-4.