Product Highlights
- 440C high-carbon martensitic precision solid shaft, UNS S44004 / 1.4125, fully compliant with ASTM A276 bar manufacturing standard
- Highest carbon grade in 400 series stainless steel with molybdenum additive, maximum hardening capacity up to HRC58–62 after quenching & tempering
- Fully magnetic under all heat treatment states, excellent wear resistance far exceeding 410 / 420 / 431 martensitic grades
- Moderate anti-rust performance against fresh water & weak corrosive atmosphere after hardening & polishing
- Supplied in fully soft annealed blank state for easy CNC turning, boring, threading and precision grinding
- Custom round shaft diameter, full length customization, all precision machining per customer CAD/PDF drawings
- Premium raw stock for precision bearing spindles, measuring tools, medical instruments and high-wear mold core shafts
Product Overview
This series 440C martensitic precision solid shafts are produced by hot rolling and cold drawing forming process. The factory standard delivery state is fully spheroidized annealing soft blank, which eliminates carbide agglomeration and ensures stable CNC machinability. Customers can conduct custom quenching and low-temperature tempering to reach target high hardness for heavy wear service.
440C is the highest-carbon martensitic stainless steel, adding molybdenum element to improve hardenability and mild corrosion resistance. Compared with other martensitic grades (410/420/431), it achieves ultra-high hardness after heat treatment, making it the preferred material for precision wear-resistant rotary components. It is widely processed into bearing mandrels, measuring fixture shafts, surgical instrument spindles, mold ejector cores and high-load mechanical transmission shafts for bearing manufacturing, medical equipment, precision molds and general machinery industries.
Material Grade Characteristics – 440C (UNS S44004 / 1.4125)
- High-carbon chromium-molybdenum martensitic stainless steel, carbon content 0.95–1.20%
- A large number of chromium carbides formed after quenching & tempering, deliver outstanding abrasion resistance
- Molybdenum improves hardening depth and mild anti-pitting performance in fresh water environment
- Soft spheroidized annealed delivery state reduces cutting tool loss during precision machining
- 100% magnetic after any heat treatment, suitable magnetic fixture rotary parts
- Optimal hardness range HRC58–62 after oil quenching + low-temperature temper; temper above 400°C will reduce hardness & corrosion resistance
Chemical Composition (Weight %)
| Grade |
EN No. |
C |
Si ≤ |
Mn ≤ |
P ≤ |
S ≤ |
Cr |
Ni ≤ |
Mo |
Fe |
| 440C |
1.4125 |
0.95–1.20 |
1.00 |
1.00 |
0.040 |
0.030 |
16.0–18.0 |
0.75 |
0.40–0.70 |
Balance |
Mechanical Properties (Spheroidized Fully Annealed, ASTM A276)
| Property |
440C Annealed Shaft |
440C Quenched & Tempered (160℃) |
| Delivery Condition |
Hot Rolled / Cold Drawn, Spheroidized Fully Annealed, Stress‑Relieved, Pickled |
| Minimum Tensile Strength (MPa) |
≥760 |
≥1960 |
| Minimum 0.2% Yield Strength (MPa) |
≥420 |
≥1890 |
| Minimum Elongation (50mm gauge) |
≥12% |
≥2% |
| Max Brinell Hardness (Annealed) |
≤269 HB |
580 HB / HRC58–62 |
Related Material Grades
- Martensitic Stainless Steel: 410, 420, 431, 440A, 440B, 440C
- Ferritic Stainless Steel: 409, 430, 439, 444
- Austenitic Stainless Steel: 304, 304L, 316L, 321, 904L
- Duplex Stainless Steel: 2205, 2507, S32750, F51
- PH Stainless Steel: 17-4PH, 15-5PH
- Nickel Alloys: Monel400/K500, Inconel600/625/718, Incoloy825/925
- Alloy & Carbon Steel: A105, 4140, F22, F91
Key Advantages
1 Ultra-High Wear Resistance After Heat Treatment
Highest hardness among common martensitic stainless steel grades, perfect for long-term friction-bearing precision shaft components.
2 Molybdenum-Enhanced Corrosion Performance
Molybdenum element improves anti-pitting ability compared to 410/420, applicable for fresh water and light humid working environments.
100 Magnetic Performance
Maintain magnetism after annealing, quenching or tempering, fit magnetic positioning fixture spindles.
Soft Annealed Machinable Blank
Spheroidized annealing optimizes carbide distribution, reduce tool wear during precision turning and grinding.
Customized Hardness Option
Adjust temper temperature to balance hardness and toughness to match light/heavy wear working requirements.
Typical Applications
- Precision Bearing Industry: Bearing mandrels, bearing race hollow shafts, miniature bearing spindle blanks
- Medical Equipment: Surgical instrument shafts, dental tool core rods, precision fixture spindles
- Mold Manufacturing: High-wear mold ejector pins, injection mold core shafts
- Measuring Tools: Calibration gauge spindles, precision positioning rotary rods
- General Machinery: High-load gear shafts, pump wear-resistant spindles, nozzle core pins
Processing Service
We provide integrated hot rolling & cold drawn precision solid shaft production, full custom CNC processing per customer CAD/PDF drawings:
- Custom fixed-length cutting, facing, centering, external turning & chamfering
- Precision threading, spline machining, cylindrical precision grinding & mirror polishing
- Custom quenching + low-temperature temper heat treatment service for target HRC hardness
- Surface pickling, passivation anti-rust finishing treatment
We supply 440C precision solid shafts for bearing, medical, mold and precision machinery global industrial clients.
Quality Assurance
- 100% UT & Eddy Current dual inspection to detect rolling segregation and surface crack defects
- Full batch tensile, yield & hardness mechanical testing per heat lot
- High-precision micrometer to control diameter & straightness tolerance
- Spectrometer full spectrum chemical composition analysis verification
- Metallographic martensite & carbide microstructure inspection after heat treatment
Mill Test Certificate EN 10204 3.1 can be issued and delivered together with shipment documents before delivery.
Packing & Delivery
Packing
- Inner: Independent anti-rust plastic sleeve + waterproof film full wrap for surface scratch protection
- Outer: Reinforced fumigated wooden pallet with separation strips to avoid bending & collision damage
- Custom heavy-duty export packaging for extra long/large-diameter shafts available upon request
Lead Time
Normally 10 – 45 working days after receiving advance payment. Exact lead time depends on shaft diameter, length, order quantity and custom heat treatment/machining demands.
