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Manufacturing services
CNC turning and milling · From 1 part
Pins, shafts, axles, gears, landing gear parts and tooling in 4340 steel, machined from your file. Upload your CAD and order online, starting at a single part.
Pivot pin
4340 Steel · Ø38 × 8 mm head · Ø25 × 100 mm body · Ø6 cotter pin hole · ¼-28 grease fitting · CNC turned
1 pc
$88.89 USD
per part
25 pcs
$26.81 USD
per part
-69.84%100 pcs
$24.16 USD
per part
-72.82%4340 steel (UNS G43400, ASTM A29 / A322, AMS 6414) is a nickel-chromium-molybdenum alloy steel. It through hardens even in thick sections and, quenched and tempered, combines very high strength with toughness and good fatigue life. That is why it is used for pins, shafts, axles, gears and landing gear parts. At PREMSA we CNC turn and mill it from your file, starting at a single part with an instant price.
Engineering properties of 4340 steel: strength, hardness, heat treatment and what matters for machining it.
Material Type
Nickel-chromium-molybdenum (Ni-Cr-Mo) alloy steel
Primary Characteristics
Very high strength, toughness, good fatigue life, through hardens
Tensile Strength (Ultimate)
745 MPa (108 ksi) annealed; 1,000–1,800 MPa (145–260 ksi) quenched and tempered
Tensile Strength (Yield)
470 MPa (68 ksi) annealed; 860–1,600 MPa (125–230 ksi) quenched and tempered
Shear Strength
≈ 450 MPa (65 ksi) annealed; rises with hardening
Elongation at Break
22% annealed; 8–16% quenched and tempered
Brinell Hardness
217 HB annealed; 28–32 HRC pre-hardened; up to 50–54 HRC quenched and tempered
Density
7.85 g/cm³ (0.284 lb/in³)
Elastic Modulus
29,000 ksi (200 GPa)
Poisson’s Ratio
0.29
Thermal Conductivity
44.5 W/m·K
Coefficient of Thermal Expansion
12.3 µm/m·°C
Melting Range
1415–1540 °C (2580–2800 °F)
Machinability
Medium: annealed or pre-hardened (28–32 HRC) it is machined with carbide, good rigidity and coolant
Weldability
Difficult: needs preheat and post-weld heat treatment
Formability
Low
Corrosion Resistance
Low: it rusts; protected with black oxide, phosphate or a coating
Heat Treatment
Oil quenched from 815–845 °C and tempered; also nitrided
Common Forms
Round bar, plate and forgings; annealed or pre-hardened
Typical Applications
Pins, shafts, axles, gears, crankshafts, landing gear parts, tooling
Material Composition
Carbon 0.38–0.43%, manganese 0.60–0.80%, silicon 0.15–0.35%, nickel 1.65–2.00%, chromium 0.70–0.90%, molybdenum 0.20–0.30%, phosphorus 0.035% max, sulfur 0.040% max, balance iron
ASTM Standard
ASTM A29 / A322 (bar); AMS 6414 / 6415 (aerospace)
Rating across key engineering and manufacturing criteria.
Strength
Weight
Machinability
Weldability
Formability
Corrosion Resistance
Thermal Resistance
Cost Efficiency
Upload your CAD file and get an instant price and delivery date. CNC turning and milling from one part to production.
We CNC turn and mill 4340 steel parts that carry loads, rotate and take impacts.
Pivot pins
Shafts and axles
Gears
Crankshafts
Landing gear parts
Tooling
High-strength bolts
Bushings and sleeves
Custom 4340 parts
What people ask most about 4340 steel parts: what it is, what it is used for, composition, hardness, hardening, equivalents, strength, welding, rust, price and tolerances.
4340 steel is chosen for parts that carry heavy loads, rotate or take impacts and can’t fail: pins, shafts, axles, gears and landing gear parts.
At PREMSA Industries we machine 4340 with CNC turning and milling from your file, from a prototype to production.
4340 is chosen when the part needs very high strength and toughness at the same time.
If your drawing doesn’t specify tolerances, we machine to ISO 2768-m (medium). On dimensions you call out —diameters, threads, holes and fits— we can hold ±0.025 mm (±0.001 in), and critical dimensions are checked in inspection. If the part is hardened after machining, fit dimensions are left oversize and ground at the end.
4340 is machined with CNC turning, CNC milling, drilling and tapping, annealed or pre-hardened.
4340 is quenched and tempered to the hardness the part calls for.
Because it carries heavy loads and takes impacts, 4340 is used in many parts made with CNC machining.
4340 is usually the right choice when the part carries heavy loads, rotates or takes impacts and can’t fail.