347 Stainless Steel Pipe Description

Main Characteristics:

  • Contains tantalum and niobium for improved resistance to intergranular corrosion.
  • Maintains high strength while preserving ductility, allowing for reduced material thickness.
  • Used extensively in welding applications for high-temperature components.

Heat Treatment:

  • Solid solution treatment (C) at 980-1150°C followed by rapid cooling.

Mechanical Properties (Solution Treated):

  • Yield Strength: ≥ 205 MPa
  • Tensile Strength: ≥ 520 MPa
  • Elongation: ≥ 35%
  • Hardness (HBS): ≤ 187
  • Hardness (HRB): ≤ 90
  • Hardness (HV): ≤ 200


347 stainless steel, known for its high chromium and nickel content, is enhanced with tantalum and niobium to resist intergranular corrosion. It maintains structural integrity under high temperatures and is particularly suitable for welding applications. After solid solution treatment, it exhibits excellent mechanical properties, making it a preferred choice in industries requiring strength and corrosion resistance.


347/347H Stainless Steel Product Introduction

347 and 347H stainless steels are stabilized austenitic stainless steels known for their excellent resistance to intergranular corrosion. This article provides a comprehensive overview of 347/347H stainless steel, covering its chemical composition, mechanical properties, performance characteristics at different temperatures, industry applications, shapes and sizes, production standards, welding and processing capabilities, advantages and disadvantages, and a comparison with similar alloys.

Chemical Composition

347 and 347H stainless steels have similar chemical compositions, with the main difference being the carbon content in 347H for improved high-temperature strength.

ElementComposition (%) for 347Composition (%) for 347H
Chromium (Cr)17.0 – 19.017.0 – 19.0
Nickel (Ni)9.0 – 13.09.0 – 13.0
Manganese (Mn)2.0 max2.0 max
Silicon (Si)0.75 max0.75 max
Carbon (C)0.08 max0.04 – 0.10
Phosphorus (P)0.045 max0.045 max
Sulfur (S)0.030 max0.030 max
Niobium (Nb)10xC – 1.108xC – 1.10

Mechanical Properties

347/347H stainless steels exhibit excellent mechanical properties suitable for various applications:

Tensile Strength, ksi (MPa)75 (515) min
Yield Strength (0.2% offset), ksi (MPa)30 (205) min
Elongation (% in 2 inches)40 min
Hardness, Rockwell B (HRB)90 max

Performance Characteristics

347/347H stainless steels offer several performance advantages:

  • High Temperature Resistance: Excellent resistance to oxidation and creep at elevated temperatures up to 1000°C.

  • Intergranular Corrosion Resistance: Contains niobium which stabilizes the alloy against sensitization and intergranular corrosion.

  • Weldability: Good weldability with standard welding techniques, with care needed to avoid hot cracking.

Industry Applications

347/347H stainless steels find applications across various industries requiring corrosion resistance and high-temperature performance:

Industry SectorApplications
Chemical ProcessingReactor vessels, heat exchangers, and piping systems handling corrosive chemicals.
AerospaceExhaust systems, jet engine parts, and aircraft components.
Oil and GasOffshore platforms, oil refinery equipment, and pipelines.
Power GenerationBoiler components, superheater tubes, and turbine blades.

Shapes and Sizes

347/347H stainless steels are available in various forms and sizes:

  • Forms: Sheets, plates, bars, pipes, tubes, and forgings.

  • Sizes: Thickness ranging from 0.1 mm to 100 mm for plates, and diameter ranging from 1 mm to 500 mm for round bars.

Production Standards

347/347H stainless steels conform to international production standards ensuring quality and reliability:

Product FormShapes AvailableSizes AvailableProduction Standards
Plates/SheetsSheets, PlatesThickness: 0.1 mm – 100 mmASTM A240, ASME SA-240
Bars/RodsRound bars, Square barsDiameter: 1 mm – 500 mmASTM A276, ASME SA-276
Pipes/TubesSeamless, WeldedOD: 6 mm – 2500 mmASTM A312, ASME SA-312

Welding and Processing

347/347H stainless steels offer good weldability and processing characteristics:

  • Welding: Can be welded using standard welding techniques such as GTAW (TIG) and GMAW (MIG), with preheating and post-weld heat treatment sometimes required for thick sections.

  • Machinability: Can be machined using conventional methods, with low cutting speeds and adequate coolant recommended.

Advantages and Disadvantages

AdvantagesExcellent high-temperature strength and corrosion resistance, good weldability, and intergranular corrosion resistance due to niobium stabilization.
DisadvantagesHigher cost compared to non-stabilized austenitic stainless steels, reduced mechanical properties at cryogenic temperatures.

Comparison with Similar Alloys

347/347H stainless steels are often compared with other stabilized austenitic stainless steels like 321 and 317L. Here’s a brief comparison:

Alloy Type/Property347/347H Alloy321 Alloy317L Alloy
Chemical CompositionContains niobium for stabilization against intergranular corrosion.Contains titanium for stabilization against sensitization.Contains molybdenum for improved corrosion resistance in acidic environments.
Mechanical PropertiesHigher strength and creep resistance compared to 321.Similar strength, but lower creep resistance compared to 347.Lower strength but better corrosion resistance compared to 347.
ApplicationsHigh-temperature applications requiring intergranular corrosion resistance.Heat exchangers, chemical processing equipment.Chemical and petrochemical industries requiring corrosion resistance.

This detailed article introduces 347/347H stainless steel, highlighting its chemical composition, mechanical properties, performance characteristics, industry applications, available forms and sizes, production standards, welding and processing capabilities, as well as advantages, disadvantages, and a comparison with similar alloys. Engineers and professionals seeking a stainless steel alloy with excellent high-temperature performance and corrosion resistance will find 347/347H alloy suitable for a wide range of applications in challenging environments.