Steel grades

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.

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

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.

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.

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 spring steel. Near-eutectoid composition (0.70-0.80% C). Excellent elastic properties after hardening and tempering. Limited hardenability — effective oil quench diameter ≤12mm. Cost-effective for small/medium springs. Used for spring wire, clock springs, saw blades, retaining rings, and precision strip springs. ≈ AISI 1075.

High-carbon spring strip steel — C 0.70-0.80%. Between C67S (0.65-0.72%) and C85S (0.83-0.90%). Good fatigue strength and edge retention. Used for flat springs, leaf springs, saw blades, snap rings, and reed valves. Available as cold-rolled precision strip in hardened & tempered condition (HRC 58-62).

Highest-carbon standard unalloyed spring steel. 0.75-0.85% C gives maximum hardness (60+ HRC) among unalloyed grades but with increased brittleness. Limited hardenability — effective quench diameter ≤10mm. Used for high-hardness springs, saw blades, scrapers, and precision strip where maximum elastic limit is needed. ≈ AISI 1080.

Highest-carbon unalloyed spring strip steel — C 0.83-0.90%. Maximum achievable hardness (HRC 62-65) and fatigue strength in the cold-rolled spring strip series. Used for the most demanding flat spring applications where maximum hardness is critical: saw blades, scraper blades, precision springs, and high-frequency reed valves. Higher C than C67S (0.65-0.72%) and C75S (0.70-0.80%).

Soft martensitic (supermartensitic) stainless steel with good corrosion resistance and high toughness. Low carbon prevents embrittlement. The standard material for hydraulic turbine runners, pump impellers, compressor components, and offshore valves.

Plain carbon quenched & tempered steel — 0.57-0.65% C. Highest practical C for Q&T without excessive brittleness. Good surface hardness (HRC 55-60) with adequate core toughness. Modern designation C60E (EN 10083-2), traditional Ck60 still widely used. Used for crankshafts, connecting rods, rail wheels, axles, and machine tool spindles where alloy cost is not justified.

Premium high-carbon high-chromium cold-work tool steel with vanadium and molybdenum. Air-hardening with minimal distortion. Superior wear resistance and edge retention. The global benchmark for cold stamping dies, blanking tools, shear blades, and forming tools.

Cold-rolled unalloyed low-carbon steel for cold forming. Base grade of the DC family (DC01-DC07). Good formability for bending, coining, beading, and simple drawing operations. Smooth surface suitable for coating and painting. Formerly designated St12.

Cold-rolled steel for moderate drawing applications. Better formability than DC01, not as good as DC04. The "middle" grade in the EN 10130 drawing steel series. Used for moderate deep-drawing applications, automotive body panels (non-critical areas), white goods housings, and general presswork.

Cold-rolled low-carbon steel for deep drawing. Higher formability than DC01/DC03 — suitable for difficult drawing and profiling operations. Used for automotive body panels, deep-drawn kitchen sinks, complex stampings, and precision-formed components.

Cold-rolled steel for extra deep drawing. The highest formability grade in the EN 10130 drawing steel series (r-value ≥1.8). Very low yield strength for excellent deep drawability. Used for complex deep-drawn automotive body panels (doors, fenders), kitchen sinks, washing machine drums, and any severe stamping application.

Interstitial-free (IF) cold-rolled steel — the absolute best formability of all automotive steels. Ultra-low carbon (<0.02%) with Ti/Nb microalloying to scavenge interstitial C and N. r-value ≥2.1. Used for the most demanding deep-drawn body panels (door inners, complex fenders, quarter panels) and structural reinforcements requiring extreme formability.

Modified D2 cold-work tool steel developed by Daido Steel (Japan). Refined Cr-Mo-V composition with higher tempering temperature capability gives ~2x the toughness of standard D2 at equal hardness (62-63 HRC). Used as D2 replacement for progressive dies, blanking tools, and cold forging where chipping is a problem.

The most widely used duplex (austenitic-ferritic) stainless steel. Balanced 50/50 microstructure provides twice the yield strength of 304/316L with superior chloride and stress corrosion resistance. Used in oil & gas, chemical processing, marine, and pulp & paper industries.