Stainless Steel – Grade 348 (UNS S34800)

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 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 2.0
Silicon, Si 1.0
Nb + Ta 0.8
Cobalt, Co 0.2
Tantalum, Ta 0.1
Carbon, C 0.080
Phosphorous, P 0.045
Sulfur, S 0.030

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 ( @ 0-100°C/32-212°F) 17.3 µm/m°C 9.61 µin/in°F
Thermal conductivity (@ 100°C/212°F) 16.3 W/mK 113 BTU in/hr.ft².°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 sightly 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.

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