¬ AISI304
» AISI304

Definition : 

304 quality is the most commonly, and in a versatile way, used stainless steel in the world. It has ability to be perfectly shaped and welding capability. Austenitic structure of 304 provides to perform deep drawing without intermediate annealing, and therefore, it is preferred in manufacturing which requires deep drawing such as sink, natural gas chimneys and saucepan. It can be used for various purposes in sectors such as industry, architecture, transportation. 
It is the 304 type in which 304L carbon is found less. Its Nickel (Ni) ratio is a bit higher compared to 304 (see alloy table). Austenitic structure provides excellent toughness to these qualities, and it preserves the toughness even in crotonoic temperatures.  It is slightly difficult to process; processing 304L is comparatively more difficult than doing 304.



Chemical Composition :


Quality

C

Mn

Si

P

S

Cr

Mo

Ni

N

304

min.
max.

-
0.08

-
2.0

-
0.75

-
0.045

-
0.030

18.0
20.0

-

8.0
10.5

-
0.10

304L

min.
max.

-
0.030

-
2.0

-
0.75

-
0.045

-
0.030

18.0
20.0

-

8.0
12.0

-
0.10

 

Corrosion Resistance : 


Its corrosive resistance is really good at 304 and 304L normal atmospheric environment. In hot environments with acids, it is possible for capillary cracks and holes to occur in the inner structure of the material and for slits, caused by the tension, to exist when the temperature is above 60 °C.
On standard temperatures, it is durable against 200 mg/L chlorine in domestic water, and against 150 mg/L chlorine at above 60 °C.

 

Heat Resistance : 

304 has a good oxidation resistance in environments which become 870 °C with intervals and continuously become 925 °C. However, if the environment is watery and the temperature is between 425 - 860 °C, corrosion resistance reduces. Since carbon(C) of 304L is low, carbide sedimentation does not occur in these environments.

 

Heat Treating (Annealing) : 

Annealing is made at 1000 - 1100 ºC and 5 minutes for each thickness in mm. After annealing, it is cooled in the air. For the flat products thicker than 2mm, cooling is performed in water. Color changes and oxide layer occurrence after annealing decreases corrosion resistance, therefore these kinds of plates should be kept away. ( With Chemical or Mechanic methods)

 

Mechanic Features :


Quality

Tensile Resistance 
(MPa) 
min

Yielding Resistance 0.2% Proof
(MPa)
min

Stretching
(% in 50mm)
min

Hardness

Rockwell B 
(HR B) 
max

Brinell 
(HB) 
max

304

515

205

40

92

201

304L

485

170

40

92

201

 

Physical Features :



Quality

Density (kg/m3)

Coefficient of Elasticity (GPa)

Thermal expansion coefficient (mm/m/°C)

Thermal Conductivity (W/m.K)

Specific Heat 0-100°C (J/kg.K)

Electricity resistance (nW.m)

0–100°C

0–315 °C

0–538 °C

at 100°C

at 500°C

304/L

8000

193

17.2

17.8

18.4

16.2

21.5

500

720

 

Areas of Use :

Food processing equipment, a part of beer sector, dairy processing and wine making
Kitchen, boat tools and equipment (sink, armature, pot, handrail etc.)
Architectural exterior coatings (panel, rail etc.)
Chemical transport containers
Heat exchangers
Bolts, nuts, screws, etc.
Springs