1.4125 X105CrMo17 UNS S44004 440C Stainless Steel

1. Introduction

440C is a high-carbon martensitic stainless steel designed for applications that demand very high hardness, strong wear resistance, and stable cutting performance after heat treatment. Its defining chemistry is built around about 1.0% carbon and 16–18% chromium, with molybdenum present in the common international specifications to improve hardenability and support corrosion performance.

In the annealed condition, 440C remains machinable enough for secondary processing, but its real value appears after quenching and low-temperature tempering, when it can reach around 58–60 HRC depending on section size and heat-treat practice. Compared with lower-carbon 440 grades, it offers higher attainable hardness and edge retention, while corrosion resistance remains moderate rather than outstanding. It is magnetic in all conditions and is widely used where a combination of wear resistance, polishability, and reasonable corrosion resistance is required.

Equivalent Grades

Note: These designations are commonly used to refer to the same material family across major markets, but minor chemistry differences can exist by standard and product form.

2. Applications

440C is typically selected for parts that must keep a hard edge, resist abrasion, or maintain bearing-type contact under load after heat treatment.

• Bearing balls
• Bearing races and race rings
• Bushings and wear sleeves
• Knife blades and industrial cutting knives
• Surgical blades and precision cutting instruments
• Valve seats and valve balls
• Pump wear parts
• Measuring instruments and gauge components
• Textile machinery wear parts
• Precision fixtures requiring hardened, polished surfaces

3. Specifications & Standards

440C appears in long-product, wire, and aerospace-related stainless steel specifications, with product form depending on the standard family. For exact supply condition, we match the order to the governing designation and required product shape.

4. Available Sizes & Delivery

FUSHUN METAL can supply 440C in rolled round bar, rolled flat bar, forged round bar, and forged flat bar forms. For common market supply, rolled bars are typically available in the small-to-medium diameter range, while forged bars cover larger sections; our 6,000-ton forging press and GFM radial forging machine give us the flexibility to produce heavy-section stock and near-net forged blanks for demanding machining routes.

We can also arrange plate, wire, or tube supply when the order basis and governing standard call for those forms. For common grades, we can offer ready stock with single-piece ordering and about 7-day delivery. For custom forged or rolled orders, MOQ is usually 3 tons with around 30-day lead time. For small-batch special grades, our small induction furnace can start from 3–5 tons. For large orders, 30–60 ton EAF heats help us keep delivery efficient.

5. Chemical Composition

The composition ranges below reflect the published limits for the main 440C designations. The ASTM/EN/JIS versions are very close; GOST 95Kh18 is a nearest equivalent with slightly different carbon, chromium, and molybdenum behavior.

6. Melting & Processing

For 440C, we can build the melt route around EAF + LF + VD for standard industrial supply. When the project requires tighter cleanliness or inclusion control, ESR or PESR can be added. For premium applications with the highest internal-quality demand, VIM + VAR is available. Because this is a stainless steel grade, an AOD refining stage can also be added where the chemistry window and clean-steel target require it. In practice, we select the route together with the customer based on cleanliness level, section size, machining allowance, and final service requirement.

7. Mechanical Properties

The verified public data available for 440C is strongest for room-temperature properties after annealing and after quenching plus tempering. Public datasheets also caution that the grade is not generally recommended for sub-zero service or for elevated-temperature service beyond the tempering range above 400°C.

The above tempered values are published for approximately 25 mm section size and are typical room-temperature results after heat treatment.

8. Heat Treatment

For best results, 440C should be tempered promptly after quenching while still hand warm, and tempering above 400°C is generally avoided because corrosion resistance and impact properties decrease.

9. Surface Finish & Machining

For 440C, we can supply black-surface rolled or forged stock for rough machining, peeled or turned round bars for improved concentricity, ground bars for tighter size control, and milled or CNC-finished flats and custom blanks for precision parts. As a practical guide, black surface stock is usually around Ra 6.3–12.5 μm, turned stock around Ra 1.6–3.2 μm, and ground stock around Ra 0.4–0.8 μm, with final dimensional tolerance controlled to drawing and section size. Because 440C machines best in the fully annealed condition, we normally recommend machining allowance based on final heat-treatment distortion and the customer’s target finish.

10. Quality Assurance & Inspection

Our quality control starts before melting and continues through final packing. Chemistry is checked heat by heat, mechanical properties are verified by tensile, hardness, and elongation testing, and dimensions are measured throughout processing. Metallographic inspection can be arranged when the order requires microstructure verification, and ultrasonic testing can be performed on bars and forgings with full-length or full-volume scanning according to the governing product standard or customer acceptance criteria.

Corrosion testing can be added when the contract or end use requires it. We can provide EN 10204 3.1 certificates, and 3.2 certificates can also be arranged when needed. Third-party inspection by SGS, TÜV, or similar agencies is available. FUSHUN METAL operates under ISO 9001 and AS9100 quality systems.

11. Packing & Shipping

Black-surface bars and forgings are bundled with steel wire or steel bands and secured to prevent movement and container damage during transit. For bright or precision-finished stock, we use protective paper, film, sleeves, wooden cases, and end protection to preserve surface quality and dimensional accuracy. Before shipment, we apply rust-preventive oil and use seaworthy export packing so the material remains protected through ocean transport and storage. We can also tailor the packing method to warehouse handling, inland trucking, or direct project delivery requirements.