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
Tempering
Hardening
Applications
Introduction
Stainless steels are high-alloy steels. They contain about 4-30% of
chromium. They are further classified into three types such as
martensitic, austenitic, and ferritic steels. Another group of
stainless steels are precipitation-hardened steels. They are a
combination of austenitic and martensitic steels.
Grade 350 stainless steel alloy is a heat treatable
austenitic/martensitic alloy. The following datasheet gives an overview
of grade 350 stainless steel alloy.
Chemical Composition
The following table shows the chemical composition of grade 350
stainless steel alloy.
| Element |
Content
(%) |
Iron, Fe
|
72.69 - 76.29
|
| Chromium, Cr |
16-17 |
| Nickel, Ni |
4 - 5 |
| Molybdenum, Mo |
2.5-3.25 |
| Manganese, Mn |
0.5-1.25 |
| Silicon, Si |
0.5 |
| Nitrogen, N |
0.07-0.13 |
| Carbon, C |
0.07-0.11 |
| Phosphorus, P |
0.04 |
| Sulfur, S |
0.03 |
Physical Properties
The physical properties of grade 350 stainless steel alloy are
highlighted in the following table.
| Properties |
Metric |
Imperial |
| Density |
7.7-8.03 cm3 |
0.278-0.290 lb/in3 |
Mechanical Properties
The following table outlines the mechanical properties of grade 350
stainless steel alloy.
| Properties |
Metric |
Imperial |
| Tensile strength |
1105 MPa |
160266 psi |
| Yield strength |
415 MPa |
60190 psi |
| Elastic modulus |
190-210 GPa |
27557-30458 ksi |
| Poisson's ratio |
0.27-0.30 |
0.27-0.30 |
| Elongation |
30% |
30% |
| Hardness |
95 |
95 |
Thermal Properties
The thermal properties of grade 350 stainless steel alloy are
displayed in the following table.
| Properties |
Metric |
Imperial |
Thermal expansion co-efficient (@
20-100°C/70-212°F)
|
11.3 µm/m°C |
6.55 µin/in°F |
Thermal conductivity (@ 38°C/100°F)
|
14.5 W/mK |
100.7 BTU in/hr.ft².°F |
Other Designations
Other designations that are equivalent to grade 350 stainless steel
alloy include:
- AMS 5546
- AMS 5548
- AMS 5554
- ASTM A579
- ASTM A693
- MIL S-8840
- AMS 5745
- AMS 5774
- AMS 5775
- SAE J467 (AM-350)
Fabrication and Heat Treatment
Machinability
Grade 350 stainless steel alloy can be machined using practices
applied on high strength stainless steels. It is recommended to use
sharp tooling, positive feeds, slow speeds, and adequate lubricant.
Welding
Grade 350 stainless steel alloy can be welded using all common
techniques except oxyacetylene welding method. After welding, this
alloy is annealed to restore maximum properties.
Hot Working
Hot working of grade 350 stainless steel alloy is performed after
heating at 1177°C (2150°F). This process is finished at 982°C (1800°F)
Cold Working
Grade 350 stainless steel alloy can be cold worked in the annealed
condition. Radical deformation of this alloy is limited due to its high
work hardening rate and the formation of martensite.
Annealing
Grade 350 stainless steel is annealed by soaking at 1010 to 1066°C
(1850 to 1950°F) followed by quenching.
Tempering
Grade 350 stainless steel is soaked at -73°C (-100°F). It is then
tempered at 454°C (850°F) to attain maximum strength or at 538°C
(1000°F) to attain maximum toughness and corrosion resistance for 3 to
4 h.
Hardening
Grade 350 stainless steel can be hardened by sub zero or double
aging. Before performing this process, this alloy is prepared by
rapidly cooling at 932°C (1710°F).
Applications
Grade 350 stainless steel is used in valve and gas turbine
components, and industrial cutters which require good strength and
corrosion resistance.