What is 1.4112 Stainless Steel?

1.4112 stainless steel, commonly known as 440B or UNS S44003, is a high-carbon martensitic stainless steel positioned between 440A and 440C in the 440 series. It offers a balanced combination of high hardness, good wear resistance, and moderate corrosion resistance, making it suitable for applications requiring greater hardness than 440A but better toughness than 440C. It is widely used for cutlery, bearings, valve components, and surgical instruments.

 

This intermediate hardness martensitic grade is recognized under several international standards.

Standard	Equivalent Grade
EN (Europe)	1.4112
ASTM/AISI (USA)	440B, UNS S44003
JIS (Japan)	SUS440B
KS (Korea)	STS440B

Its carbon content is higher than 440A but lower than 440C, balancing attainable hardness with retained toughness.

Element	C	Si	Mn	P	S	Cr	Mo
Content (%)	0.75 - 0.95	≤ 1.0	≤ 1.0	≤ 0.04	≤ 0.03	16.0 - 18.0	0.4 - 0.8

Mechanical properties vary significantly with heat treatment, offering excellent hardness potential.

 

Condition	Yield Strength (Rp0.2)	Tensile Strength (Rm)	Elongation (A)	Hardness (HRC)
Annealed	~ 450 MPa	~ 740 MPa	~ 14%	~ 25 HRC
Hardened & Tempered	≥ 700 MPa	≥ 850 MPa	≥ 10%	55 - 58 HRC

 

Key Characteristics and Applications of 1.4112 / 440B

High Hardness and Wear Resistance: Can be heat treated to achieve high hardness (55-58 HRC), providing excellent wear resistance and good edge retention for cutting applications.

Moderate Corrosion Resistance: Offers better corrosion resistance than many tool steels due to its high chromium content, but less than austenitic grades like 304. Suitable for mild corrosive environments.

Magnetic and Hardenable: Strongly magnetic and responds well to heat treatment, with through-hardening capability in sections up to moderate thickness.

Good Balance of Properties: Positioned between 440A and 440C, it offers a practical compromise between hardness and toughness.

 

Primary Applications:

Cutlery: High-quality knives, blades, scissors, and surgical instruments requiring a balance of hardness and toughness.

Bearings and Valve Parts: Ball bearings, races, valve seats, balls, and pump components where wear resistance is critical.

Industrial Tools: Gauges, measuring tools, molds, and machine parts requiring hardness and dimensional stability.

Dental and Surgical Tools: Instruments requiring sharp edges and compatibility with sterilization processes.

Nozzles and Orifices: Components subjected to abrasive fluids or particulate matter.

 

What distinguishes 440B (1.4112) from 440A and 440C?
The primary difference is carbon content: 440A has 0.60-0.75% C, 440B has 0.75-0.95% C, and 440C has 0.95-1.20% C. This results in 440B offering a middle ground-higher hardness and wear resistance than 440A (which maxes at about 56 HRC), but with better toughness and slightly easier heat treatment than 440C (which can reach 62 HRC). 440B is often chosen when a balance between hardness, toughness, and corrosion resistance is needed without the potential brittleness of 440C, particularly for applications involving impact or shock loading.

 

What is the recommended heat treatment for 440B stainless steel?
Typical heat treatment involves austenitizing at 1010-1065°C, with preheating recommended at 760-815°C to prevent thermal shock. Hold at temperature for sufficient time to dissolve carbides, then oil quench to achieve maximum hardness. Quenching should be rapid but controlled to minimize distortion. This is followed by tempering at temperatures between 150-370°C, depending on the desired balance of hardness and toughness. Lower tempering temperatures (150-200°C) yield maximum hardness (57-58 HRC); higher temperatures (300-370°C) increase toughness with some reduction in hardness (54-56 HRC). Double tempering is often used to ensure complete stress relief and dimensional stability. Sub-zero treatment immediately after quenching can increase hardness slightly by transforming retained austenite.

 

Looking for a Reliable Supplier of 1.4112 / 440B Stainless Steel?
GNEE Steel supplies high-quality 440B (1.4112) stainless steel in bar, wire, strip, and plate forms, available in annealed condition for machining or pre-hardened to customer specifications. We provide full material certification (EN 10204 3.1) and processing support including precision cutting, grinding, and heat treatment services. If you have any requirements, please feel free to contact us.