Introduction
Stainless steels have high corrosion resistance when compared to other steels due to the presence of large amounts of chromium. Based on their crystalline structure, they are further divided in to ferritic, austenitic, and martensitic steels.
Grade 348 stainless steel is similar to that of 321 stainless steel. It uses stabilizing elements such as columbium or tantalum to increase intergranular corrosion resistance.
The following datasheet gives an overview of grade 348 stainless steel.
Chemical Composition
The chemical composition of grade 348 stainless steel is outlined in the following table.
| Element | Content (%) |
| Iron, Fe | 66 |
| Chromium, Cr | 19 |
| Nickel, Ni | 11 |
| Manganese, Mn | 2 |
| Silicon, Si | 1 |
| Nb + Ta | 0.8 |
| Cobalt, Co | 0.2 |
| Tantalum, Ta | 0.1 |
| Carbon, C | 0.08 |
| Phosphorous, P | 0.045 |
| Sulfur, S | 0.03 |
Physical Properties
The physical properties of grade 348 stainless steel are displayed in the following table.
| Properties | Metric | Imperial |
| Density | 8 g/cm3 | 0.289 lb/in3 |
| Melting point | 1427 C | 2600 F |
Mechanical Properties
The following table shows the mechanical properties of annealed grade 348 stainless steel.
| Properties | Metric | Imperial |
| Tensile strength | 655 MPa | 95000 psi |
| Yield strength (@ strain 0.200%) | 275 MPa | 39900 psi |
| Izod impact | 120 - 160 J | 88.5 - 118 ft-lb |
| Charpy impact | 160 J | 118 ft-lb |
| Shear modulus (typical for steel) | 77.0 GPa | 11200 ksi |
| Elastic modulus | 190-210 GPa | 27557-30458 ksi |
| Poisson's ratio | 0.27-0.30 | 0.27-0.30 |
| 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 thermal properties of grade 348 stainless steel are displayed in the following table.
| Properties | Metric | Imperial |
| Thermal expansion co-efficient ( @ 0-100C/32-212F) | 17.3 m/mC | 9.61 in/inF |
| Thermal conductivity (@ 100C/212F) | 16.3 W/mK | 113 BTU in/hr.ft.F |
Other Designations
Other designations equivalent to grade 348 stainless steel are included in the following table.
| ASTM A167 | ASTM A312 | ASTM A479 | QQ S766 | ASME SA376 |
| ASTM A182 | ASTM A314 | ASTM A580 | ASME SA182 | ASME SA403 |
| ASTM A213 | ASTM A336 | ASTM A632 | ASME SA213 | ASME SA409 |
| ASTM A240 | ASTM A358 | ASTM A813 | ASME SA240 | ASME SA479 |
| ASTM A249 | ASTM A376 | ASTM A814 | ASME SA249 | MIL-S-23196 |
| ASTM A269 | ASTM A403 | DIN 1.4550 | ASME SA312 | SAE 30348 |
| ASTM A276 | ASTM A409 | MIL S-23195 | ASME SA358 | SAE J405 (30348) |
Fabrication and Heat Treatment
Machinability
Grade 348 stainless steel is slightly tougher than grade 304 stainless steel. Hardenability of this alloy will be reduced if constant positive feeds and slow speeds are used.
Welding
Grade 348 stainless steel can be welded using fusion and resistance welding methods. Oxyacetylene welding method is not preferred for this alloy. AWS E/ER348 filler metal can be used when required.
Hot Working
Grade 348 stainless steel can be hot worked at 1149-1232°C (2100-2250°F). It should not be heated below 927°C (1700°F). It is water quenched or fully annealed to restore corrosion resistance property.
Cold Working
Grade 348 stainless steel is ductile and tough, and can be readily blanked, stamped, drawn and spun.
Annealing
Grade 348 stainless steel is annealed at 1010-1093°C (1850-2000°F) followed by quenching in water.
Hardening
Grade 348 stainless steel does not react to heat treatment. However, elevated properties can be obtained by cold reduction.
Applications
Grade 348 stainless steel is used in different kinds of nuclear applications.
Source - www.azom.com
(www.steelguru.com)
