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
Aging
Applications
Introduction
Stainless steels are high-alloy steels. They contain about 4-30% of
chromium. They are classified into three types such as martensitic,
austenitic, and ferritic steels. Another group of stainless steels are
precipitation-hardened steels. They result from a combination of
austenitic and martensitic steels.
Grade 450 stainless steel alloy is a martensitic type stainless
steel. It has high ductility and strength. It has a yield strength
which is nearly 3 times the strength of grade 304 stainless steel. The
following datasheet gives an overview of grade 450 stainless steel
alloy.
Chemical Composition
The following table shows the chemical composition of grade 450
stainless steel alloy.
| Element |
Content
(%) |
| Iron, Fe |
74.3 |
| Chromium, Cr |
15 |
| Nickel, Ni |
6 |
| Copper, Cu |
1.5 |
| Silicon, Si |
1.0 |
| Manganese, Mn |
1.0 |
| Molybdenum, Mo |
0.75 |
| Niobium, Nb (Columbium, Cb) |
0.40 |
| Carbon, C |
0.050 |
| Phosphorous, P |
0.030 |
| Sulfur, S |
0.030 |
Physical Properties
The physical properties of grade 450 stainless steel alloy are
displayed in the following table.
| Properties |
Metric |
Imperial |
| Density |
7.80 cm³ |
0.282 lb/in³ |
Mechanical Properties
The following table outlines the mechanical properties of grade 450
stainless steel alloy.
| Properties |
Metric |
Imperial |
| Tensile strength |
986 MPa |
143000 psi |
| Yield strength (@ strain 0.200%) |
814 MPa |
118000 psi |
| Bulk modulus (typical for steel) |
166 GPa |
24100 ksi |
| Shear modulus (typical for steel) |
83.9 GPa |
12200 ksi |
| Charpy impact |
125 - 141 J |
92.2 - 104 ft-lb |
| Elongation at break (gage length is
4 times specimen diameter) |
13.30% |
13.30% |
| Hardness, Brinell (converted from
Rockwell C hardness) |
278 |
278 |
| Hardness, Knoop (converted from
Rockwell C hardness) |
296 |
296 |
| Hardness, Rockwell C |
28 |
28 |
| Hardness, Vickers (converted from
Rockwell C hardness) |
287 |
287 |
Thermal Properties
The thermal properties of grade 450 stainless steel alloy are
displayed in the following table.
| Properties |
Metric |
Imperial |
| Thermal expansion co-efficient ( @
20-100°C/68-212°F) |
10.1 µm/m°C |
5.61 µin/in°F |
| Thermal conductivity (typical value
for stainless steel) |
20.7 W/mK |
144 BTU in/hr.ft².°F |
Other Designations
Other designations that are equivalent to grade 450 stainless steel
alloy include:
- AMS 5763
- AMS 5773
- AMS 5859
- AMS 5863
- ASTM A564 (XM-25)
- ASTM A693 (XM-25)
- ASTM A705 (XM-25)
Fabrication and Heat Treatment
Machinability
Grade 450 stainless steel alloy uses feeds and speeds comparable
with other martensitic stainless steels. It is preferred to use
positive feeds and slow speeds to achieve good results.
Welding
Grade 450 stainless steel alloy can be welded using shielded methods
to reduce contamination.
Hot Working
Grade 450 stainless steel alloy can be hot worked by soaking at
1150-1177°C (2100-2150°F) followed by cooling and fully annealing.
Cold Working
Grade 450 stainless steel alloy can be cold worked using all common
techniques.
Annealing
Grade 450 stainless steel alloy is annealed by soaking at
1024-1052°C (1875-7925°F) for 1 h followed by quenching in water or oil.
Aging
Grade 450 stainless steel alloy is soaked at specific temperature
for 4 h followed by cooling to obtain condition H900, H950, H1000,
H1050 or H1150.
Applications
Grade 450 stainless steel alloy is mainly used in applications where
martensitics fail in terms of corrosion resistance, and standard
austenitics fail in terms of strength requirements in corrosive
environments.