347 Stainless Steel Data Sheet

GENERAL PROPERTIES

 
Alloy 347 (UNS S34700) is a columbium stabilized austenitic stainless steel with good general corrosion resistance and somewhat better resistance in strong oxidizing conditions than 321 (UNS S32100). It has excellent resistance to intergranular corrosion after exposure to temperatures in the chromium carbide precipitation range of 800 – 1500°F (427 – 816°C). The alloy has good oxidation resistance and creep strength to 1500°F (816°C). It also possesses good low temperature toughness. Alloy 347H (UNS S3409) is the higher carbon (0.04 – 0.10) version of the alloy. It was developed for enhanced creep resistance and for higher strength at temperatures above 1000°F (537°C). In most instances, the carbon content of the plate enables dual certification. Alloy 347 cannot be hardened by heat treatment, only by cold working. It can be easily welded and processed by standard shop fabrication practices. 

• Resistance to corrosion  
• Prevention of product contamination 
• Resistance to oxidation  
• East of fabrication 
• Excellent formability  
• Beauty of appearance 
• Ease of cleaning 
• High strength with low weight 
• Good strength and toughness at cryogenic temperatures  
• Ready availability of a wide range of product forms  

RESISTANCE TO CORROSION

Alloy 347 exhibits good general corrosion resistance that is comparable to 304. It was developed for use in the chromium carbide precipitation range of 800 – 1500°F (427 – 816°C) where un-stabilized alloys such as 304 are subject to intergranular attack. In this temperature range, the overall corrosion resistance of Alloy 347 is superior to Alloy 321. Alloy 347 also performs somewhat better than Alloy 321 in strongly oxidizing environments up to 1500°F (816°C). The alloy can be used in nitric solutions, most diluted organic acids at moderate temperatures and in pure phosphoric acid at lower temperatures and up to 10% diluted solutions at elevated temperatures. Alloy 347 resists polythionic acid stress corrosion cracking in hydrocarbon service. It can also be utilized in chloride or fluoride free caustic solutions at moderate temperatures. Alloy 347 does not perform well in chloride solutions, even in small concentrations, or in sulfuric acid.  

PHYSICAL PROPERTIES

MECHANICAL PROPERTIES 

CHEMICAL PROPERTIES 

WELDING 

 
Alloy 904L can be readily welded by most standard processes. Austenitic plate materials have a homogeneous austenitic structure with an even distribution of alloying elements. Solidification after welding causes the redistribution of certain elements such as molybdenum, chromium and nickel. These segregations remain in the cast structure of the weld and can impair the corrosion resistance in certain environments. Segregation is less evident in 904L, and this material is normally welded using a filler metal of the same composition as the base metal and can even be welded without filler metal. The welding consumables for 904L are 20 25 CuL covered electrode  
 
 

HEAT TREATMENT 
 
 

 
Working temperatures of 1562 – 2102°F (850 –1150°C) are recommended for hot working processes. Normally hot working should be followed by a solution anneal and quench, but for 904L, if hot forming is discontinued at a temperature above 2012°F (1100°C)  and the material is quenched directly thereafter, the material may be used without subsequent heat treatment. It is important that the entire workpiece be quenched from temperatures above 2012°F (1100°C). In the event of partial heating or cooling below 2012°F (1100°C), or if the cooling has been  too  slow, hot working should always be followed by a solution anneal and quenching. 904L should be solution annealed at 1940–2084°F (1060–1140°C)