1.4401 Specifications
1.4401 and 1.4404 are stainless steel types also known as grades 316 and 316L respectively. Second only to 304 in its commercial importance, Grade 316 is an austenitic grade steel containing an addition of molybdenum, giving it improved corrosion resistance, particularly apparent for pitting and crevice corrosion in chloride environments. Due to the austenitic structure, 316 stainless steel has exceptional toughness, even at very low, cryogenic temperatures.
The low carbon variant of 316 stainless steel, 316L is well suited for use in heavy gauge welded components (over 6mm). This is due to it’s immunity to grain boundary carbide precipitation (sensitisation). 316H (high carbon) and 316Ti (stabilised grade) should be used for elevated temperature applications. 316Ti contains a small amount, only around 0.5% of titanium. This helps stabilise the structure of 316 at temperatures above 800c, meaning it can be held at much higher temperatures while preventing carbide precipitation and it prevents the steel from corroding. 316Ti retains the physical and mechanical properties that are present in standard 316 grades.
Applications
316 was initially developed to be used in paper mills, but is now used in the following applications:
Food processing equipment
Brewery equipment
Chemical and petrochemical equipment
Laboratory benches & equipment
Coastal architectural panelling
Coastal balustrading
Boat fittings
Chemical transportation containers
Heat exchangers
Mining screens
Nuts and bolts
Springs
Medical implants
Chemical Compositions
| Element | % Present |
| Chromium (CR) | 16.50 – 18.50 |
| Nickel (Ni) | 10.00 – 13.00 |
| Molybdenum (Mo) | 2.00 – 2.50 |
| Manganese (Mn) | 0.0 – 2.00 |
| Silicon (Si) | 0.0 – 1.00 |
| Nitrogen (N) | 0.0 – 0.11 |
| Carbon (C) | 0.0 – 0.07 |
| Phosphorous (P) | 0.0 – 0.05 |
| Sulphur (S) | 0.0 – 0.03 |
| Iron (Fe) | Balance |
Alloy Designations
Stainless Steel grade 316 (1.4401) also corresponds to the following designations but may not be a direct equivalent:
UNS S31600
316S31
EN 58H
Mechanical Properties
| Property | Value |
| Proof Stress | 200 Min MPa |
| Tensile Strength | 500 to 700 MPa |
| Elongation A50 mm | 40 Min % |
| Hardness Brinell | 215 Max HB |
Corrosion Resistance
Even when exposed to a wide range of corrosive environments and material, 316 has great resistance. Regarded as a “marine grade” stainless steel, it is not resistant to warm sea water, and warm chloride environments can cause pitting and crevice corrosion. 316 can also be subject to stress corrosion cracking when above 60°c
Machinability
Grade 316/1.4401 has excellent machinability which can be enhanced using the following:
• Cutting edges must be kept sharp. Dull edges will cause excess work hardening
• Cuts should be light but deep enough to prevent work hardening by riding on the surface of the material
• Chip breakers should be employed to assist in ensuring swarf remains clear of the work
• Low thermal conductivity of austenitic alloys results in heat concentrating at the cutting edges. This means coolants and lubricants are necessary and must be used in large quantities
