1.4305, DIN X8CrNiS18-9, AISI 303

1.4305, DIN X8CrNiS18-9, AISI 303

Designation by Standards

 

Chemical Composition (in weight %)

Description
303 is one of the most popular of all the free machining stainless steels. It offers good strength, corrosion resistance and great machinability. It will resist scaling at temperatures up to 871^oC.

Applications
Used in an incredibly wide variety of parts both in screw and general machining industries. Applications include hardware, fasteners, valve parts, nozzles and trim. For the food processing industry, dairies, fotographic industry, for paint,soap, paper and textile production.

Physical properties (avarage values) at ambient temperature
Modulus of elasticity [10³ x N/mm²]: 203, 186 (200^oC), 172(400^oC)
Density [g/cm³]: 7.9
Thermal conductivity [W/m.K]: 14.6
Electric resistivity [Ohm mm²/m]: 0.73
Specific heat capacity[J/g.K]: 0.502

Coefficient of Linear Thermal Expansion 10^{-6 o}C^-1

Hardening
Harden from a temperature of 1020-1070^oC followed by water quenching. Structure is austenite with small ferrite component.

Mechanical properties in solution-annealed condition and reistance to intercrystalline corrosion
Hardness: 130-190 HB
0.2 % proof stress: 190 N/mm² (for d<=160)
1.0 % proof stress: 225 N/mm² (for d<=160)
Tensile strength: 510-750 N/mm²
Elongation: 35% (for d<=160, longit.)
Resistance to interystalline corrosion: no (in as delivered condition), no (in sensitised condition)
Note: Sensitisation treatment for 15 min at 700^oC with subsequent cooling in air.

Mechanical Properties At Elevated Temperatures

Forging
Hot forming temperature: 1150-850^oC.

Machinability
Excellent speeds and feeds are capable with this material. The addition of sulfur causes a very brittle chip. Many companies now offer premium machinability grades, such as CarTech with their Project 70 and 7000 series.

Corrosion Resistance
Resistant to a variety of organic and inorganic chemicals, fresh water and atmospheric corrosion.

Welding
Although not recommended, welding may be performed if low temperatures are employed. Recommended filler metal is AWS E/ER312. At high temperature, the sulfur in 303 tends to precipitate at the weld boundary resulting in weak and brittle joints.

Cold working
Minor deformation is possible with this alloy, although it is not its strong point. Type 303 Se is superior in this aspect.