Materials database

Medium-carbon Cr-Mo quench and temper steel. Lower C than 42CrMo4 for better weldability and toughness. Used for welded pressure vessels, seamless tubes for high-temperature service, bicycle frames, and moderately stressed machine components.

Free-cutting variant of 34CrMo4 (1.7220) — S 0.020-0.040% for improved machinability on CNC automatics. Same Q&T properties. Used for high-volume CNC production of shafts, connecting rods, bolts, and automotive drivetrain components where machining cycle time is critical.

High-strength quenched and tempered Cr-Ni-Mo steel. Excellent hardenability and toughness, suitable for large cross-sections. Used for heavy-duty shafts, gears, turbine parts, and aerospace components.

Free-cutting variant of 34Cr4 (1.7033) — sulfur addition (0.020-0.040%) for improved machinability on CNC automatics. Same QT properties as 34Cr4. Used for shafts, spindles, bolts, studs, and automotive components in high volume on automatic lathes.

Nickel-chromium quenched and tempered steel with 1.2–1.6% Ni and 0.9–1.1% Cr for high strength and excellent impact toughness. Good hardenability for uniform properties in medium cross-sections. Used for heavy-duty engine parts, crankshafts, gears, shafts, piston rods, and bolts. Important grade in aerospace (AIR 9160/C as 35NC6) and heavy mechanical engineering.

Nickel-chromium-molybdenum QT steel with 1.2-1.6% Ni for good toughness and hardenability. Between 34CrNiMo6 and 39NiCrMo3 in the alloy series. Good balance of strength, toughness, and fatigue resistance. Used for large crankshafts, heavy gears, turbine shafts, and highly stressed bolts in energy and heavy machinery sectors.

Boron micro-alloyed QT steel — 0.0008-0.0050% B multiplies hardenability dramatically at minimal cost. Achieves similar through-hardening to 41Cr4 or 42CrMo4 at lower alloy cost. THE cost-optimized approach for automotive fasteners, bolts, and cold-forged QT parts. Used for high-strength bolts (class 10.9/12.9), tie rods, stabilizer bars, and any mass-produced QT part where total alloy cost per ton matters.

Chromium-molybdenum Q&T steel — between 25CrMo4 (lower C) and 42CrMo4 (higher C). Good balance of through-hardenability and toughness for medium-sized parts. Used for shafts, gears, bolts, studs, and structural components in oil/gas and power generation. Better weldability than 42CrMo4 due to lower C.

Cr-Ni-Mo quenching and tempering steel for medium-high strength applications. Good balance of strength and toughness. Used for automotive connecting rods, crankshafts, gears, high-strength bolts, and heavily loaded machine parts.

Boron-alloyed cold heading steel — Mn 0.8-1.1%, B 0.0008-0.005%. Designed for cold-forged, then quenched & tempered high-strength fasteners (class 10.9). Good cold formability before heat treatment. Used for bolts, screws, studs, and rivets produced by cold heading followed by Q&T. Lower cost than CrMo grades for fastener applications.

Ultra-high-strength nickel-chromium-molybdenum QT steel. 4% Ni gives exceptional deep hardenability — air-hardening up to 90mm, through-hardening up to 300mm. UTS 1100-1300 MPa QT with good toughness. White-spot sensitive — dehydrogenation after forging mandatory. French designation 35NCD16. Used for landing gear, aerospace structural parts, heavy-duty shafts, racing components, and mining/construction equipment.

Simple chromium QT steel without Mo — lower cost than CrMo grades. 1% Cr gives adequate hardenability for small-to-medium sections (up to ~40mm). Close to AISI 5135. Used for bolts, studs, axles, shafts, and general mechanical engineering where moderate strength suffices and Mo premium is not justified.

Free-machining variant of 37Cr4 with controlled sulfur addition (0.020–0.040%) for improved chip-breaking during automated machining. Chromium steel with good hardenability for medium cross-sections. Same mechanical properties as 37Cr4 after quenching and tempering. Used for automotive and mechanical engineering components: shafts, connecting rods, crankshafts, and bolts.

Low-chromium (0.4–0.6% Cr) alloy steel for quenching and tempering with moderate hardenability. Economical alternative to higher-alloyed Cr steels for lighter-duty applications. Cold forging grade suitable for stressed machine and vehicle components, quenched-and-tempered screws, and bolts. Good machinability in annealed condition.

Boron press-hardening steel — higher C (0.36-0.42%) than 22MnB5 (0.20-0.25%) for higher final strength (UTS ~1800 MPa vs ~1500 for 22MnB5). Used for ultra-high-strength automotive structural parts where 22MnB5 is not strong enough: A/B-pillar reinforcements, bumper beams, door intrusion beams. Hot-stamped at 880-950°C then die-quenched to full martensite.

Microalloyed precipitation-hardened forging steel. Achieves high strength directly from forging heat — no separate quench & temper needed. Cost-effective alternative to QT steels for automotive crankshafts, connecting rods, and other high-volume forged components.

Silicon spring steel with lower C (0.35-0.42%) than 55Si7 — better toughness and fatigue life at the cost of slightly lower maximum hardness. Si (1.5-1.8%) gives excellent hot sag resistance to ~250°C. THE automotive engine valve spring material in many European OEMs. Also used for clutch springs, suspension springs, and applications requiring fatigue endurance under dynamic loading.

Nickel-chromium-molybdenum quench & temper steel. Similar to AISI 4340 but with lower Ni — more economical. Good hardenability for sections up to ~80mm. Excellent balance of strength, toughness, and fatigue resistance. High white-point sensitivity — hydrogen control required. Used for crankshafts, connecting rods, gear shafts, landing gear components, and heavy-duty machinery parts.

NiCrMo quenched & tempered steel — excellent combination of strength (UTS 1000-1200 MPa) and toughness. Ni 0.9-1.2% gives good low-temperature impact. Between 34CrNiMo6 (higher alloy) and 42CrMo4 (no Ni) in the performance/cost spectrum. Used for heavy-duty axles, crankshafts, large bolts, connecting rods, and hydraulic cylinder rods.

Lowest-chromium ferritic stainless steel with Ti stabilization. Developed specifically for automotive exhaust systems as a cost-effective alternative to austenitic grades. Good oxidation resistance to ~800°C. Used for exhaust manifolds, catalytic converters, mufflers, and heat shields.

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.

Pre-hardened plastic mold steel — delivered at 28-32 HRC, ready for machining without further heat treatment. The European equivalent of AISI P20. Cr-Mn-Mo composition for good through-hardenability in large sections. THE workhorse mold base material for injection molds, compression molds, and die casting dies. Good machinability, polishability, and photo-etchability. Used for mold frames, large injection molds, blow molds, and structural die components.

Free-machining variant of 40CrMnMo7 (1.2311/P20) — sulfur addition (0.05-0.10%) for significantly improved machinability. Same pre-hardened delivery condition (28-32 HRC). 30-40% faster machining than 1.2311. Slight trade-off in polishability due to MnS inclusions. Used where machining cost matters more than mirror polish: large mold frames, structural mold components, and prototype molds.

Pre-hardened mould steel with nickel addition for uniform hardness through large cross-sections. Delivered at 280-325 HB. The Ni addition (0.90-1.20%) provides better through-hardening than 1.2311/1.2312, making it suitable for large moulds with sections >400mm. Used for large injection moulds for automotive, household appliance, and furniture industry. The standard choice for large, complex mould frames. Similar to AISI P20+Ni.