347-347H Stainless Steel Plate

347/347H Stainless Steel

347 is a stable austenitic chromium steel containing niobium, which can eliminate carbide precipitation, thereby preventing intergranular corrosion. Alloy 347 is stabilized by the addition of chromium and tantalum, offering higher creep and stress-rupture properties compared to alloys 304 and 304L, and is suitable for applications where sensitization and intergranular corrosion are a concern. The addition of niobium also imparts excellent corrosion resistance to alloy 347, even superior to alloy 321. 347H is a higher carbon form of alloy 347, demonstrating improved high-temperature and creep properties.

Spec: UNS S34700 / S34709

Standard:

ASTM/ASME：UNS S34700 / S34709

EURONORM：FeMi35Cr20Cu4Mo2

DIN：2.4660

Chemical Composition

Mechanical properties: (See attached image:)

Weldability

Austenitic stainless steel is considered to be the easiest to weld among all high-alloy steels.

Weldable via all熔焊 and 电阻焊 processes

Heat Treatment

The annealing temperature range is from 1800 to 2000°F.

Stress-relief annealing can be performed within the carbide precipitation range of 800 to 1500°F without any risk of subsequent intergranular corrosion; cannot be hardened through heat treatment.

Corrosion Resistance:

Offer corrosion resistance similar to alloy 304

Applications for alloys (such as Alloy 304) prone to intergranular corrosion

Commonly used for heavy-duty welding equipment that cannot be annealed and for equipment operating between 800 to 150°F (427 to 816°C).

In water and other low-temperature environments, 347 alloy is superior to 321 alloy.

Primarily used in high-temperature environments requiring desensitization to prevent low-level intergranular corrosion.

Susceptible to stress corrosion cracking

Demonstrate similar corrosion resistance to all other 18-8 Austenitic stainless steels

Application:

Alloy 347 is commonly used in the manufacture of equipment that must operate under severe corrosion conditions and is also prevalent in the oil refining industry. Typical applications that consistently employ Alloy 347 include:

High-temperature chemical process

Heat exchanger tube

High-Temperature Steam Service

High-pressure steam pipe

Radiation Overheater

Boiler Tube

Heavy-duty exhaust system

Typical Refinery Pipelines