When it comes to high-temperature industrial environments, standard stainless steel grades like 304 often fall short due to chromium carbide precipitation. This is where ASTM A240 Type 347 Stainless Steel Shim stock becomes indispensable. Stabilized by the addition of columbium (niobium) and tantalum, ASTM A240 347 Stainless Steel offers exceptional resistance to intergranular corrosion and excellent mechanical strength in elevated temperature zones.
Whether you are looking for a reliable ASTM A240 347 Stainless Steel Shim Manufacturer or verifying material data for precision engineering, this comprehensive guide covers the critical technical data, chemistry, and applications of ASTM A240 Type 347.
ASTM A240 347 Specification & Overview
The ASTM A240 347 Specification covers chromium, chromium-nickel, and chromium-manganese-nitrogen stainless steel plate, sheet, and strip for pressure vessels and general applications. A shim manufactured under this standard ensures high dimensional accuracy, uniform thickness, and a smooth surface finish.
SS 347 Shim Specification Table
| Parameter | Technical Details |
| Standard | ASTM A240 / ASME SA240 |
| Grade | ASTM A240 Grade 347 Shim (UNS S34700) |
| Type | ASTM A240 Type 347 |
| Thickness Range | 0.01 mm to 3.0 mm (Varies by manufacturer) |
| Hardness | Annealed (Max 92 HRB / 201 HBW) |
| Finish | 2B, BA, Polished, Cold Rolled (CR) |
ASTM A240 Type 347 Chemical Composition
The defining feature of ASTM 347 Stainless Steel is its stabilization chemistry. The addition of Columbium (Nb) prevents carbide precipitation during welding and exposure to high temperatures (between 800°F and 1500°F).
The exact ASTM A240 Type 347 Chemical Composition requires the columbium content to be at least 10 times the carbon content, capping at a maximum limit:
- Carbon (C): 0.08% Max
- Chromium (Cr): 17.0% – 19.0%
- Nickel (Ni): 9.0% – 13.0%
- Columbium + Tantalum (Nb + Ta): $10 \times \text{C Min} / 1.0\% \text{Max}$
- Manganese (Mn): 2.0% Max
- Silicon (Si): 0.75% Max
- Phosphorus (P): 0.045% Max
- Sulfur (S): 0.030% Max
- Iron (Fe): Balance
ASTM A240 347 Mechanical Properties
The ASTM A240 347 Mechanical Properties highlight why ASTM A240 Gr 347 is favored over lower-alloy variants. It retains higher creep and stress rupture properties compared to Grade 304 or 321.
- Tensile Strength (Minimum): $515 \text{ MPa} \text{ (75,000 psi)}$
- Yield Strength (0.2% Offset, Minimum): $205 \text{ MPa} \text{ (30,000 psi)}$
- Elongation (in 50mm, Minimum): 40%
- Hardness (Rockwell B, Maximum): 92 HRB
ASTM A240 347 Equivalent Grades
When sourcing A240 347 Stainless Steel Shim stock globally, it helps to know international structural equivalent designations:
- UNS: S34700
- Werkstoff / EN: 1.4550
- AFNOR: Z6CNNb18-10
- BS: 347S31
- JIS: SUS 347
ASTM A240 347 Stainless Steel Thickness Chart
Because precision alignments require exact tolerances, standard ASTM A240 347 Material shims are cold-rolled to tightly controlled thickness limits. Below is a standard thickness matrix commonly provided by leading suppliers:
| Thickness (mm) | Thickness (Inches) | Tolerance (± mm) |
| 0.025 mm | 0.001” | 0.004 mm |
| 0.050 mm | 0.002” | 0.005 mm |
| 0.100 mm | 0.004” | 0.008 mm |
| 0.250 mm | 0.010” | 0.015 mm |
| 0.500 mm | 0.020” | 0.025 mm |
| 1.000 mm | 0.040” | 0.035 mm |
| 2.000 mm | 0.080” | 0.050 mm |
ASTM A240 Grade 347 Shim Uses & Applications
Thanks to its stabilization, the ASTM A240 347 Shim Applications span across aggressive, high-temperature, and corrosive sectors.
Sourcing an ASTM A240 Type 347 Stainless Steel Shim Supplier in India
When standard austenitic steel is subjected to temperatures between 425°C and 815°C, chromium carbides precipitate at the grain boundaries, leaving the steel vulnerable to corrosion. In Grade 347, the columbium preferentially combines with carbon to form harmless columbium carbides, leaving the chromium intact to protect against oxidation.
Key Applications:
- Aerospace & Rocketry: Manifolds, exhaust collector rings, and high-temperature engine gaskets.
- Petrochemical & Chemical Processing: Used in heat exchangers, oil refinery equipment, and catalytic cracking units where precision spacing and shimming are necessary.
- Power Generation: Superheater tubes, boiler casings, and heavy-duty industrial steam valve components.
- Automotive: High-performance exhaust systems, turbocharger flanges, and joint expansion elements.
Sourcing an ASTM A240 Type 347 Stainless Steel Shim Supplier in India
If you are procuring raw materials for global projects, partnering with a certified ASTM A240 Type 347 Stainless Steel Shim Supplier in India provides an excellent balance of competitive pricing, strict compliance with ASTM standards, and robust material documentation (including Mill Test Certificates to EN 10204 3.1).
