Sep 26 2012
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Other Designations
Fabrication and Heat Treatment
Machinability
Welding
Hot Working
Cold Working
Annealing
Hardening
Introduction
Stainless steels are high-alloy steels which have high corrosion
resistance than other steels owing to the presence of large amounts of
chromium in the range of 4 to 30%. Stainless steels are classified into
martensitic, ferritic and austenitic based on their crystalline
structure. In addititon, they form another group known as
precipitation-hardened steels, which are a combination of martensitic
and austenitic steels.
The following datasheet will provide more details about grade 347H
stainless steel, which is slightly tougher than grade 304 steel.
Chemical Composition
The following table shows the chemical composition of grade 347H
stainless steel.
| Element |
Content
(%) |
| Iron, Fe |
62.83 - 73.64 |
| Chromium, Cr |
17 - 20 |
| Nickel, Ni |
9 - 13
|
| Manganese, Mn |
2 |
| Silicon, Si |
1 |
| Niobium, Nb (Columbium, Cb) |
0.320 - 1 |
| Carbon, C |
0.04 - 0.10 |
| Phosphorous, P |
0.040 |
| Sulfur, S |
0.030 |
Physical Properties
The physical properties of grade 347H stainless steel are given in
the following table.
| Properties |
Metric |
Imperial |
| Density |
7.7 – 8.03 g/cm3 |
0.278 – 0.290 lb/in³ |
Mechanical Properties
The mechanical properties of grade 347H stainless steel are
displayed in the following table.
| Properties |
Metric |
Imperial |
| Tensile strength, ultimate |
480 MPa |
69600 psi |
| Tensile strength, yield |
205 MPa |
29700 psi |
| Rupture strength (@750°C/1380°F,
time 100,000 hours) |
38 - 39 MPa, |
5510 - 5660 psi |
| Elastic modulus |
190 – 210 GPa |
27557 – 30458 ksi |
| Poisson’s ratio |
0.27 – 0.30 |
0.27 – 0.30 |
| Elongation at break |
29% |
29% |
| Hardness, Brinell |
187 |
187 |
Other Designations
Other designations that are equivalent to grade 347H stainless steel
include the following:
- ASTM A182
- ASTM A213
- ASTM A240
- ASTM A249
- ASTM A271
- ASTM A312
- ASTM A336
- ASTM A376
- ASTM A403
- ASTM A430
- ASTM A479
- ASTM A813
- ASTM A814
- SAE 30347H
Fabrication and Heat Treatment
Machinability
Machining grade 347H stainless steel is slightly tougher than that
of grade 304 steel. However, the hardenability of this steel can be
minimized by the use of constant positive feeds and slow speeds.
Welding
Grade 347H stainless steel can be welded using most of the
resistance and fusion methods. Oxyacetylene welding is not preferred
for this steel.
Hot Working
Forging, upsetting and other hot work processes can be performed at
1149 to 1232°C (2100 to 2250°F). The grade 347H steel has to be water
quenched and annealed to obtain maximum hardness.
Cold Working
Grade 347H stainless steel can be readily stamped, blanked, spun and
drawn as it is quite tough and ductile.
Annealing
Grade 347H stainless steel can be annealed at temperature ranging
from 1010 to 1193°C (1850 to 2000°F) and then quenched with water.
Hardening
Grade 347H stainless steel is unresponsive to heat treatment. The
hardness and strength of the steel can be increased through cold
working.