Austenitic 304 Grade

Austenitic Stainless Steels are most known, most commonly used and having  largest application spectrum grades.
Its nichel content and abilitily to accept other alloys allow to austenitic staiinless steels to have strenght agaist chemical corrosive environment even on high temperatures. Austenitic Stainless steels can be used for very sophisticated applications and they can be adapted to several applications by adding differant alloys.
For example, 301 grade has an elesticity and used for springs, wires. Fishing hooks and known as “spring Steel”.
303  is known for its perfect machinability so used for manufacturing machine parts, axes, spidles etc.
AISI 304 is the most common Stainless Steel grade as it was one the earliest introduced grade. It has a large application spectrum and used to be called “18-8 chrom Steel” since the first applications.
AISI 304 grade Stainless stell is used from kitchen utensils to kitchen equipment, medical apparatus, food and beverage industries, chemical processes, -250 C crygenic applications, storage tanks, oudoor applications etc. Due its machinability, high strenghjt, ductility, anti-corrosive and anti-magnetic structure.
AISI 304 grade can be found at any commercial form as coils, sheets, plates, tubes, pipes, flat bars, round and hexagonals, rods, wires, profilkes etc as it has a wide application.
AISI 304 has subgrades as 304 L where carbon content decreased to improve ductility and on DDQ quotation for deep drawing and pressing.
304 grade’s resistance to heat can be improved by adding Titanium and it is called 321 grade and become resistant to up to 1100 C to be used on furnaces, heat exhangers, etc.
304-304H-304L-321 PHYSİCAL SPECIFICATIONS
(On 20°C if not specified.)
 
304
321
Units
Density
7,85 x 10 ³**      
7,8 x 10 ³**      
kg/m³
Elasticity Module
193
193
GPa
Poisson Rate
0,26
0,24
 
Specific Heat
500
500
J/kg K
Termal Conductivity:
 
 
 
   100°C ‘de
16,2
16,1
W/mK
   500°C ‘de
21,5
22,2
W/mK
Electrical Resistivity
72
72
nWm
Mean Thermal Expension
Rate Classes
   0 – 100°C
17,2
16,6
µm/mK
   0 – 315°C
17,8
17,2
µm/mK
   0 – 540°C
18,4
18,6
µm/mK
   0 – 700°C
18,9
19,0
µm/mK
Melting
1400 – 1450   
1400 – 1430    
C°
Magnetic Specification
Non Magnetic*
Non Magnetic*
 

* Basicly it is not magnetic ve may have a light magnetism after cold machinning.
** Those figures are real densities, for theoretical calculatiuon use 8,07kg/m²/mm

304 304L 304H 321/32H Units
Tensile Streght 485 min 485 min 515 min 515 min MPa
Ezilme Mukavemeti (0,2% gerilim) 205 min 170 min 205 min 205 min MPa
Elongation(50mm içinde) 40 min 40 min 40 min 40 min %
Brinell Hardness 202 max 183 max 202 max 217 max

SPECIFICATIONS FOR HIGH TEMPERATURES

TENSILE STRENGHT FOR ELEVATED TEMPARATURE FOR SHORT DURATION

Temperature°C 600 700 800 900 1000
MPa 304 365 240 125 60 35
MPa 321 340 260 160 90 50

CAPILAR SHEAR STRENGHT AFTER 10.000 HOURS

Temperature°C 540 600 650 700 800
Capilar Shear Strenght MPa 304 250 153 95 60 24
Capilar Shear Strenght MPa 304L 172 107 67 40 18
Capilar Shear Strenght MPa 321 175 170 105 63 24

SUGGESTED MAXIMUM SERVICE TEMPERATURE (ON CORROSIVE CONDITIONS)

304 321
Continious 925C 925C
Intermiteed 850C 870C

Graphics Copyright: Columbus Steel