High Carbon 440c Stainless Steel Flat Bar 1.4125 Precision Tools ISO 9001

Product Description

Product Description

440C Stainless Steel Flat Bar (1.4125 / UNS S44004)

High-carbon martensitic stainless steel flat bar for bearings, cutting tools and precision wear parts, produced and inspected under the FUSHUN METAL ISO 9001 quality system.

1. Introduction

440C stainless steel, also known as UNS S44004, EN 1.4125 and X105CrMo17, is a high-carbon martensitic stainless steel built for maximum hardness and wear resistance. With roughly 1.0% carbon and 16 to 18% chromium, it reaches the highest hardness of any standard stainless grade after quench and temper, while still keeping moderate corrosion resistance. It is chosen where extreme wear resistance, edge retention and dimensional stability matter more than toughness or severe-corrosion performance.

FUSHUN METAL produces 440C as flat bar, rolled round and strip for customers in the bearing, cutlery, surgical instrument, valve, mould, pump, textile and aerospace industries. Our production route begins with 30 to 60 ton electric-arc furnace heats, followed by ladle refining and continuous casting to keep the structure clean and uniform. Heavy sections are finished on a 6,000-ton press and a GFM radial forging machine, while small special grades can be started from a 3 to 5 ton induction furnace. Every heat is made under our ISO 9001 quality management system, from melting through forging to final dimensional and chemical inspection, giving buyers a consistent, fully traceable material they can specify with confidence.

2. Equivalent Grades and Standards

440C is referenced under many international systems. The table below lists the main designations and specifications so buyers can match the grade to their own drawing, purchasing standard or mill test requirement.

System	Grade / Specification
UNS	S44004
ASTM	A276, A473, A580, A493, A479, F899
AMS	5630, 5880, 5618, AMS-QQ-S-763
EN	1.4125 (X105CrMo17), EN 10088-3
DIN	X105CrMo17, W-Nr 1.4125
JIS	SUS440C, JIS G4303
GOST	95Kh18 (95Х18)
GB	108Cr17 / 9Cr18Mo, GB/T 1220

FUSHUN METAL can match any of these designations on the order and issue a mill test certificate confirming the chemistry and delivery condition for the selected standard.

3. Applications by Industry

440C is used for parts that must hold a hard, polished, wear-resistant surface after heat treatment. By industry, the typical components produced from FUSHUN METAL flat bar are:

Bearings: bearing balls, inner and outer races, race rings, rollers and cage components for pumps, motors and aircraft assemblies.

Cutlery and tools: knife blades, industrial cutting knives, razor blades, scissors and shear edges requiring a lasting sharp edge.

Medical: surgical blades, scalpels, dental and orthodontic instruments where a fine, clean polished finish is essential.

Valves and pumps: valve seats, valve balls, pump wear rings, mechanical seal faces, nozzles and bushings.

Moulds and measurement: mould cores, die inserts, punches, measuring gauges, micrometers and caliper jaws.

General industry: wear sleeves, textile machinery parts, bushings and selected structural aircraft parts.

Compared with lower-carbon 440A and 440B grades, 440C gives the highest attainable hardness and the best edge retention, which is why it is preferred for demanding wear parts rather than for corrosion-first service. FUSHUN METAL cuts flat bar to the sizes these parts require and can supply pre-machined blanks to reduce customer processing time and scrap.

4. Supply, Dimensions, Delivery and Surface

FUSHUN METAL supplies 440C in several product forms and wide size ranges to suit different machining routes:

Rolled round bar: diameter 2 to 300 mm (larger forged sections on request), length 3000 to 6000 mm.

Rolled flat bar: thickness 3 to 120 mm, width 10 to 400 mm, length 3000 to 6000 mm.

Cold-rolled strip: thickness 0.1 to 6.0 mm, width up to 300 mm, in coil or cut length.

Forged bar: round and flat produced on our 6,000-ton press and GFM radial forging machine for heavy sections and near-net shapes.

Delivery condition: annealed (≤269 HB, about 97 HRB) for easy machining, or hardened and tempered (58 to 62 HRC) supplied against order.

Surface condition: black, peeled, turned, ground or bright polished, chosen to match the customer's finishing process.

Common grades are available from stock with about 7-day delivery; custom rolled or forged orders typically need a 3-ton minimum and around 30-day lead time. Each bar is straightened, measured and marked with heat number before packing. FUSHUN METAL packs every order for export and ships the mill test certificate with the material, so the supplied size, condition and chemistry are documented from our furnace to the customer's workshop.

5. Chemical Composition (ASTM A276 / EN 1.4125 / JIS SUS440C)

The 440C chemistry is defined by ASTM A276, EN 10088-3 (1.4125) and JIS G4303. The typical limits in weight percent are:

Element

Content %

Function

Carbon (C)

0.95 to 1.20

Drives hardness, wear resistance and edge retention

Chromium (Cr)

16.0 to 18.0

Stainless corrosion resistance and carbide formation

Molybdenum (Mo)

≤ 0.75

Improves hardenability and pitting resistance

Manganese (Mn)

≤ 1.00

Steelmaking control element

Silicon (Si)

≤ 1.00

Deoxidation during melting

Phosphorus (P)

≤ 0.040

Controlled residual impurity

Sulfur (S)

≤ 0.030

Controlled for toughness and polishability

Nickel (Ni)

≤ 0.75

Optional, supports stability

Iron (Fe)

Balance

Base metal

FUSHUN METAL controls these limits through ladle refining and secondary metallurgy, then verifies each heat by spectrochemical analysis before issuing the mill test certificate, so the composition matches the ordered standard. For critical bearing or blade applications we can tighten sulfur and apply cleaner melting practice on request to improve polishability and fatigue life.

6. Mechanical Properties (Heat-Treated Condition)

440C is normally supplied annealed and then hardened and tempered by the user. Representative properties for both conditions are listed below.

Hardened and tempered (austenitize 1010 to 1065°C, oil quench, temper 150 to 370°C)

Property

Typical value

Tensile strength

up to 1965 MPa (about 285 ksi)

0.2% yield strength

up to 1900 MPa (about 275 ksi)

Hardness

58 to 62 HRC (about 580 to 650 HBW)

Elongation

2 to 5% in 50 mm

Charpy impact

about 9 J

Annealed condition (as supplied for machining)

Property

Typical value

Tensile strength

760 to 950 MPa

0.2% yield strength

about 450 MPa

Hardness

≤ 269 HB (about 97 HRB)

Elongation

about 14%

Higher tempering temperatures lower hardness in exchange for slightly more toughness; for most wear parts a low temper near 150 to 200°C keeps 58 to 60 HRC. Sub-zero treatment after quench is often used for bearing parts to convert retained austenite and improve dimensional stability. FUSHUN METAL heat-treats samples from each batch and reports the actual values on the certificate, letting customers validate performance for their specific components.

 

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