Materials database

Chromium Q&T steel with higher Cr (1.3-1.6%) than 41Cr4 (0.9-1.2%) — deeper hardenability for larger ruling sections. Used for heavy shafts, large bolts, and machine components up to ~60mm ruling section where 41Cr4 would not through-harden. Also offers slightly better wear resistance and corrosion resistance than lower-Cr grades.

Chromium-molybdenum-vanadium creep-resisting steel for high-temperature fasteners and bolts per EN 10269. Excellent creep resistance up to 540°C with tensile strength 850–1000 MPa after quenching and tempering. Widely used for steam turbine bolts, pressure vessel fasteners, and power generation components. Equivalent to ASTM A193 Grade B16.

High-strength Cr-Ni-Mo quench and temper steel. Higher C than 34CrNiMo6 for greater strength, with excellent hardenability from Ni+Mo combination. Used for heavy-duty crankshafts, connecting rods, high-strength bolts (class 12.9), gears, and critical structural components in large cross-sections.

High-nickel Cr-Mo quench & temper steel for large cross-sections. 1.6-2.0% Ni gives superior hardenability compared to 39NiCrMo3 — through-hardening up to ~130mm diameter. Close to AISI 4340 composition. Used for heavy crankshafts, large gears, turbine shafts, connecting rods, and critical structural fasteners in energy and heavy machinery sectors.

High-alloy NiCrMo Q&T steel — Ni ~2%, Cr ~1%, Mo ~0.5%. Very deep hardenability for large cross-sections. UTS 1100-1300 MPa. Used for heavy-duty crankshafts, landing gear, rock drill components, and large forgings requiring uniform through-hardening. Between 34CrNiMo6 and 36NiCrMo16 in hardenability.

Medium-carbon chromium steel with good hardenability. Standard grade for induction-hardened and nitrided components. Used for crankshafts, gears, axle shafts, bolts, studs, and machine parts requiring surface hardening.

Chromium-molybdenum QT steel — very close to 42CrMo4 (1.7225) with slightly lower carbon. Essentially interchangeable with 42CrMo4 for most applications. Sometimes specified where marginally better weldability than 42CrMo4 is needed. Same applications: gears, shafts, crankshafts, bolts, hydraulic components.

Free-cutting variant of 41CrMo4 (1.7225) — S 0.020-0.040% for improved chip formation on CNC automatics. Same Q&T mechanical properties (UTS 1000-1200 MPa). THE most popular free-cutting CrMo QT steel. Used for high-volume CNC production of crankshafts, connecting rods, gears, and shafts in the automotive industry.

Free-cutting variant of 41Cr4 (1.7035) — sulfur addition (0.020-0.040%) for improved chip formation on CNC automatics. Same mechanical properties as 41Cr4 after Q&T. UTS 900-1100 MPa. Used for high-volume automotive shafts, bolts, spindles, and connecting rods on automatic lathes. Most popular Cr-only QT steel for CNC mass production.

High-strength quenched and tempered chromium-molybdenum steel. Widely used for shafts, gears, crankshafts, connecting rods, and high-strength bolts. Excellent hardenability and good fatigue resistance.

Free-cutting variant of 42CrMo4 with controlled sulfur content (0.020-0.040%). Improved machinability while maintaining essentially the same mechanical properties. Used for high-volume CNC machined components: gears, shafts, bolts, and automotive parts.

Chromium-vanadium quenched & tempered steel — higher Cr (1.3-1.6%) than 41Cr4 plus V (0.10-0.20%) for grain refinement and secondary hardening. Good fatigue life and wear resistance. Used for heavily loaded shafts, gears, piston rods, and mining equipment where higher hardenability and finer grain than 41Cr4/42CrMo4 are needed.

Vanadium-microalloyed medium-carbon steel for controlled-cooling after forging — achieves target properties without separate Q&T heat treatment ("as-forged" concept). V precipitates (VN, VC) give precipitation strengthening during air cooling. THE modern automotive crankshaft steel — replaces 42CrMo4 Q&T at lower total cost (no heat treatment furnace needed). Also used for connecting rods and large forged parts.

Ultra-high-strength NiCrMo Q&T steel — Ni 3.5-4.5%, the highest-Ni standard QT grade. UTS 1250-1450 MPa. Maximum through-hardenability for the largest cross-sections (300mm+). Used for the heaviest crankshafts, large forged rotors, press columns, and critical structural forgings in energy and defense. Comparable to AISI 4340 but with higher Ni.

Medium-carbon chromium steel for quenching and tempering. Good hardenability for medium cross-sections. Used for crankshafts, connecting rods, spindles, bolts, and other moderately stressed machine parts requiring through-hardening.

Higher-carbon CrMo Q&T steel — 0.42-0.50% C vs 0.38-0.45% for 42CrMo4. Higher maximum hardness (HRC 52-56 surface after induction) and tensile strength (UTS 1000-1200 MPa QT) at the expense of slightly reduced toughness and weldability. Used where 42CrMo4 is not quite hard/strong enough: heavy-duty gear shafts, large bolts (12.9 class), crankshafts, and torsion bars.

Silicon spring steel with high elastic limit. Standard flat/leaf spring steel in Europe. Si provides high sag resistance. Used for leaf springs, Belleville washers, lock washers, and agricultural machine springs.

High-carbon Cr-Mo steel for springs and high-strength applications. Higher carbon than 42CrMo4 for greater hardness and spring properties. Used for coil springs, leaf springs, torsion bars, highly stressed bolts, and heavy-duty shafts.

Free-cutting variant of 50CrMo4 — S 0.020-0.040% for machinability. Higher C (0.46-0.54%) than 42CrMoS4 = higher hardness after Q&T (UTS 1100-1300 MPa). Used for high-strength shafts, torsion bars, and heavy-duty bolts produced on CNC automatics where maximum CrMo strength with machinability is needed.

Chromium-vanadium spring/tool steel — identical alloy system to 51CrV4 (1.8159) but recognized as a separate grade in some standards. Dual use: heavy-duty springs (EN 10089) AND cold work tools (knives, shear blades). V improves temper resistance and grain refinement. UTS 1200-1500 QT. Used for heavy leaf springs, stabilizer bars, torsion bars, and cold work cutting tools.

CrMoV alloyed spring steel — THE European automotive suspension spring material. CrMo gives deep hardenability for large coil springs, V adds grain refinement and secondary hardening for fatigue resistance. UTS 1350-1600 MPa QT. Used for hot-formed coil springs (cars, trucks), leaf springs, torsion bars, and stabilizer bars. Excellent sag resistance to 200°C.

Chromium-vanadium spring steel. The most important European spring steel grade. Excellent fatigue resistance and high elastic limit after heat treatment. Used for coil springs, leaf springs, torsion bars, anti-roll bars, and high-strength fasteners.

Si-Cr spring steel for high-performance automotive suspension and valve springs. Lower sag tendency than 46Si7 due to Cr addition. The standard European valve spring steel. Used for suspension springs, valve springs, torsion bars, and stabilizer bars where fatigue resistance is critical.

Chromium spring steel — simpler and cheaper than 51CrV4 (no vanadium). 0.75% Cr provides adequate hardenability for flat and small-diameter round springs. Used for leaf springs, agricultural springs, lock springs, and general-purpose springs where the V-premium of 51CrV4 is not justified.