347 Stainless Steel 347 Stainless Steel Supplier Stainless Shapes is a proud 347 Stainless Steel supplier. Type 347 stainless steel has slightly improved corrosion resistance over type 321 stainless steel in strongly oxidizing environments. Stabilized with columbium, Type 347 is preferred for aqueous and low-temperature environments due to its strong resistance to intergranular attack. Both 347 and 321 exhibit good resistance to polythionic acid stress corrosion cracking, a common issue in oil refineries. Since columbium and tantalum have a stronger affinity for carbon than chromium, columbium-tantalum carbides precipitate within the grains instead of forming at the grain boundaries. Alloy 347 Stainless bar should be considered for applications requiring intermittent heating between 800ºF (427ºC) and 1650ºF (899ºC), and also for welding under conditions that prevent a post-weld anneal. Uses for 347 Stainless Steel Oil Refineries Fluid catalytic cracking units (FCC) Hanger rods Recuperator tube sheets, shell, and supports Where temperatures exceed 550°F, resistance to sulfidation is needed Fired heater tubes Distributor trays and thermowell Equipment in and around reactors (good resistance to polythionic acid) Special Attributes of SS 347 Strong Machinability – Slightly tougher than 304 stainless, this material will produce the same tough, stringy chips. Whereas, the use of slow speeds and constant positive feeds will minimize this alloy’s tendency to work harden. Easy Welding – 347 may be welded by all commonly used fusion and resistance methods. However, oxyacetylene welding is not recommended. When necessary, use AWS E/ER347 filler metal. Hot Working/Cold Working – Working Temperatures of 2100 are recommended for forging, upsetting, and other processes. Although the material requires a high initial force, it can be readily stamped, blanked, spun, and drawn for cold working. Not Sure What You’re Looking For? At Stainless Shapes, we’ve got our sales team working around the clock to help you with your stainless needs better. The 347 is also available in the 347H form and can be purchased in any of our listed shapes in Florida or Illinois. If you would like to know more about our steel or speak to a sales representative, call us today at (800) 748-9811 Furthermore, for a prompt and accurate quote, call us today. Call - 800-748-9811 Frequently Asked Questions What is the difference between 304 and 347 stainless steel? + Grade 347 contains niobium (columbium) as a stabilizing element (minimum 10x the carbon content, max 1.0%). This prevents carbide precipitation (sensitization) at 800-1650 F during and after welding -- a problem that can occur in standard 304 and reduce corrosion resistance near welds. 347 retains full corrosion resistance in welded assemblies at elevated temperatures where 304 would sensitize. What is 347 stainless used for? + Grade 347 is used for welded structures operating at elevated temperatures -- aircraft exhaust systems, jet engine components, chemical processing piping and vessels, power generation equipment, and any welded stainless assembly exposed to 800-1650 F service temperatures where intergranular corrosion must be prevented. What is the cheapest grade of stainless steel? + The most economical standard stainless grades are 409 and 430 (ferritic, minimal nickel). Among austenitic grades, 304 is the most economical entry point. Grade 347 is more expensive than 304 due to the niobium addition and tighter chemistry controls. What is the highest grade of stainless steel? + Among austenitic grades stocked by Stainless Shapes, the highest-performing grades for combined strength and corrosion resistance are duplex 2205 (for chloride environments), super-austenitic grades (904L), and precipitation-hardening grades (17-4 PH) for strength. 347 is a specialized grade for high-temperature welded service. What is the difference between 321 and 347 stainless steel? + Grade 321 is stabilized with titanium and Grade 347 is stabilized with niobium -- both for the same purpose (preventing weld sensitization at elevated temperatures). Grade 347 has slightly better high-temperature strength and is preferred for jet engine applications. Grade 321 is more commonly used in pressure vessels and heat exchangers. What are the 4 types of stainless steel? + All standard stainless grades fall within four types: austenitic (300 series), ferritic (400 series ferritic), martensitic (400 series martensitic), and precipitation-hardening. Grade 347 is austenitic. Is there a better stainless steel than 304? + Yes, Grade 321 (titanium-stabilized) is generally considered better than 304 for elevated-temperature welded service because it resists sensitization. For room-temperature applications where sensitization is not a concern, 304 is equivalent and less expensive. What's more expensive, 304 or 316 stainless? + Grade 347 is more expensive than 304 due to niobium addition but comparable to 321. It is less expensive than duplex or precipitation-hardening grades. Pricing depends on form, size, and market conditions. Is 321 stainless better than 304? + The key difference between 321 and 347 is the stabilizing element: 321 uses titanium; 347 uses niobium. Both prevent weld sensitization. 347 offers slightly higher creep strength at elevated temperatures. For aerospace jet engine applications, 347 is often preferred; for pressure vessels, 321 is more common. What is the difference between 347 and 316 stainless steel? + The key difference between 347 and 316 is purpose. Grade 347 is niobium-stabilized for elevated-temperature welded service. Grade 316 has molybdenum for superior chloride corrosion resistance at ambient temperature. For high-temperature weld-intensive applications, 347 is better; for marine or chemical corrosion resistance, 316 is the correct choice.
