Sep 26 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Welding
Hot Working
Cold Working
Annealing
Hardening
Applications
Introduction
Stainless steels are called as high-alloy steels. Due to the
presence of large amounts of chromium in the range of 4 to 30%, they
have high corrosion resistance than other steels. Stainless steels are
classified into martensitic, ferritic and austenitic based on their
crystalline structure. However, stainless steels present in the form of
a combination of martensitic and austenitic steels are known as
precipitation-hardened steels.
The following datasheet will provide more details about grade 305
stainless steel, which has high resistance to heat and corrosion.
Chemical Composition
The following table shows the chemical composition of grade 309S
stainless steel.
| Element |
Content
(%)
|
| Iron, Fe |
60 |
| Chromium, Cr |
23 |
| Nickel, Ni |
14 |
| Manganese, Mn |
2 |
| Silicon, Si |
1 |
| Carbon, C |
0.080 |
| Phosphorous, P |
0.045 |
| Sulfur, S |
0.030 |
Physical Properties
The physical properties of grade 309S stainless steel are given in
the following table.
| Properties |
Metric |
Imperial |
| Density |
8 g/cm3 |
0.289 lb/in³ |
| Melting point |
1454°C |
2650°F |
Mechanical Properties
The mechanical properties of annealed grade 309S stainless steel are
displayed in the following table.
| Properties |
Metric |
Imperial |
| Tensile strength, ultimate |
620 MPa |
89900 psi |
| Tensile strength, yield (0.2%) |
310 MPa |
45000 psi |
| Izod impact |
120 - 165 J |
88.5 - 122 ft-lb |
| Modulus of elasticity |
200 GPa |
29000 ksi |
| Shear modulus |
77 GPa |
11200 ksi |
| Poissons ratio |
0.3 |
0.3 |
| Elongation at break (in 50 mm) |
45% |
45% |
| Hardness, Brinell (converted from
Rockwell B hardness) |
147 |
147 |
| Hardness, Knoop (converted from
Rockwell B hardness) |
164 |
164 |
| Hardness, Rockwell B |
85 |
85 |
| Hardness, Vickers (converted from
Rockwell B hardness) |
169 |
169 |
Thermal Properties
The following table outlines the thermal properties of grade 309S
stainless steel.
| Properties |
Metric |
Imperial |
| Thermal expansion co-efficient (@
0-100°C/32-212°F) |
14.9 µm/m°C |
8.28 µin/in°F |
| Thermal conductivity
(@0-100°C/32-212°F) |
15.6 W/mK |
108 BTU in/hr.ft².°F |
Other Designations
Other designations that are equivalent to grade 309S stainless steel
include the following:
- AMS 5523
- AMS 5574
- AMS 5650
- ASTM A167
- ASTM A213
- ASTM A240
- ASTM A249
- ASTM A276
- ASTM A312
- ASTM A314
- ASTM A473
- ASTM A479
- ASTM A511
- ASTM A554
- ASTM A580
- ASTM A813
- ASTM A814
- DIN 1.4833
Fabrication and Heat Treatment
Machinability
Machining of grade 309S stainless steel is similar to that of grade
304.
Welding
Grade 309S stainless steel can be welded using most of the
resistance and fusion methods. Oxyacetylene welding is not preferred
for this steel.
Hot Working
Hot working of grade 309S stainless steel can be done at 1177°C
(2150°F) and reheated at 982°C (1800°F). This process is followed by
rapid cooling to obtain maximum corrosion resistance.
Cold Working
Grade 309S stainless steel can be drawn, headed, upset and stamped,
although this steel has high work hardening rate. However, it has be
fully annealed after cold-working to reduce internal stress.
Annealing
Grade 309S stainless steel can be annealed at temperature ranging
from 1038 to 1121°C (1900 to 2050°F) and then quenched with water.
Hardening
Grade 309S stainless steel is unresponsive to heat treatment. The
hardness and strength of the steel can be increased through cold
working.
Applications
The following are the major applications of grade 309S stainless
steel:
- Oven linings
- Boiler baffles
- Fire box sheets
- Furnace components
- Other high temperature containers.