904L is an austenitic stainless steel. It is softer than 316L,[1] but its molybdenum addition gives it superior resistance to localized attack (pitting and crevice corrosion) by chlorides and greater resistance reducing acids; in particular, its copper addition gives it useful corrosion resistance to all concentrations of sulfuric acid. Its high alloying content also gives it greater resistance to chloride stress corrosion cracking, but it is still susceptible. Its low carbon content makes it resistant to sensitization by welding and which prevents intergranular corrosion.

Alloy 904L (UNS N08904) is a superaustenitic stainless steel that is designed for moderate to high corrosion resistance in a wide range of process environments. The combination of high chromium and nickel content, coupled with additions of molybdenum and copper, assure good to excellent corrosion resistance.

With its highly alloyed chemistry — 25% nickel and 4.5% molybdenum, 904L provides good chloride stress corrosion cracking resistance, pitting and general corrosion resistance superior to 316L and 317L molybdenum enhanced stainless steels.

Alloy 904L was originally developed to withstand environments containing dilute sulfuric acid. It also offers good resistance to other inorganic acids such as hot phosphoric acid as well as most organic acids.

Alloy 904L is easily welded and processed by standard shop fabrication practices.

Alloy 904 (N08904) stainless steel is a high alloy austenitic product intended for use under severely corrosive conditions. It offers good resistance to:

·         Pitting and crevice corrosion

Intergranular corrosion

Stress corrosion cracking

General corrosion

Grade 904L stainless steel is a non-stabilized austenitic stainless steel with low carbon content. This high alloy stainless steel has added copper to improve its resistance to strong reducing acids, such as sulphuric acid. The steel is also resistant to stress corrosion cracking and crevice corrosion. Grade 904L stainless steel is non-magnetic, and offers excellent formability, toughness and weldability. Grade 904L contains high amounts of expensive ingredients, such as molybdenum and nickel. Today, most of the applications that employ grade 904L are replaced by low-cost duplex stainless steel 2205.

Grade 904L stainless steels have excellent resistance to warm seawater and chloride attack. The high resistance of grade 904L against stress corrosion cracking is due to the presence of high amounts of nickel in its composition. Moreover, the addition of copper to these grades develops resistance to sulphuric acid and other reducing agents in both aggressive and mild conditions.

The corrosion resistance of grade 904L is intermediate between super austenitic grades, with 6% molybdenum content, and standard 316L austenitic grades. Grade 904L is less resistant to nitric acid than grades 304L and 310L, which are free of molybdenum. This steel grade needs to be solution treated following cold working, to achieve maximum stress corrosion cracking resistance under critical environments.

Application

Construction/Indutry/Building/Chemical/Auto

l  Air Pollution Control — scrubbers for coal-fired power plants

l  Chemical Processing — process equipment for the production of sulfuric, phosphoric, inorganic and organic acids and the production of phosphate-based fertilizers

l  Metallurgical Processing — pickling equipment using sulfuric acid

l  Oil and Gas Production — offshore process equipment

l  Pharmaceutical Industry — process equipment

l  Pulp and Paper — processing equipment

l  Seawater and Brackish Water — condensers, heat exchangers and piping systems

Summary

Foshan Sewaly Steel Co., Ltd. is a large-scale comprehensive processing group mainly engaged in stainless steel coil, stainless steel strip, stainless steel plate and stainless steel pipe. We have been engaged in the stainless steel industry for 13+ years, with a monthly shipment of 5,000+ tons, a standing inventory of 15,000+ tons, and a professional team of 500+ people. The company can provide corresponding certifications according to customer requirements, such as: EN, ASTM/ASME, DIN/JUV, JIS/SUS, etc.

So far, we have the branches located in Shanghai, Jiangsu, Chengdu, Shandong, and formed a Russian team. Meanwhile, we won the first-level agent of Shanxi Taigang STSS, Fujian Hongxin Machinery Co.,Ltd., Posco Stainless Steel Co., Ltd.. The company has expanded its export business and established good cooperative relations with major foreign steel mills. Our partners include: Outokumpu Oyj, Avista Corporation, Nippon Yakin Europe Limited, ATI, JFE Steel Corporation and other companies