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Product development history

Electric arc furnace stainless steel mass production in China after 1949, early production Cr13 Martensitic stainless steel, production technology, mass production of 18-8-type Cr-Ni austenitic steels, for example, 1Cr18Ni9Ti, beginning in 1952. Subsequently, in order to meet the domestic needs of the chemical industry, and began production of Mo2%-3% such as 1Cr18Ni12Mo2Ti and 1Cr18Ni12Mo3Ti. In order to save precious element nickel, since 1959, started copying to Mn,N Ni 1Cr17Mn6Ni5N added to the AISI steel 204 Mo2%-3% and 1Cr18Mn8Ni5N,1958 years, 1Cr18Mn10Ni5Mo3N has been developed (204+Mo) for total recycle urea production plant in place of 1Cr18Ni12Mo2Ti. Late 50 and early 60 ‘s, started industrial manufacture of iron-nickel-free stainless steel such as 1Cr17Ti,1Cr17Mo2Ti and 1Cr25Mo3Ti, and began researching the fuming nitric acid corrosion resistance of high silicon stainless steel 1Cr17Ni14Si4ALTi (equivalent to grades э и 654 of the Soviet Union), the steel is actually an α + γ duplex stainless steel. 60 ‘s, because the domestic chemical, aerospace, aviation, Atomic Energy, industrial development and the use of electric oxygen steel-making technology, a large number of new steel grades, such as 17-4PH,17-7PH,PH15-7Mo precipitation hardening stainless steel, super low carbon stainless steel w/c ≤ 0.03% 00Cr18Ni10, 00Cr18Ni14Mo2, 00Cr18Ni14Mo3 and Cr-Mn-N without Ni stainless 1Cr18Mn14Mo2N ( A4) has successfully developed and put into production. 70, in order to address chemical industry and atomic power industry 18-8 appeared in Cr-Ni chloride stress corrosion of steel, α + γ Cr-Ni duplex stainless steels have been developed and production and application of primary steel 1Cr21Ni5Ti,00Cr26Ni6Ti,00Cr26Ni7Mo2Ti,00Cr18Ni5Mo3Si2 (3RE60) and 00Cr18Ni6Mo3Si2Nb.

00Cr18Ni6Mo3Si2Nb to resolve Sweden brand 3RE60 vulnerable to single phase ferritic structure after welding, leading to development of corrosion resistance and toughness decreases with n and Nb α + γ duplex stainless steel. To the 80 ‘s to address localized corrosion such as pitting, crevice corrosion of chloride damage research and imitation of second generation of n-containing α + γ duplex stainless steels, such as 00Cr22Ni5Mo2N,00Cr25Ni6Mo3N and 00Cr25Ni7Mo3WCuN, not only formed a series of duplex stainless steel in China, but also delved into their structures and properties in mechanism in duplex stainless steel and n. 70, China stainless steel material progress to other important studies: development of high-strength and ultra-high strength maraging stainless steel and industrial development and application of vacuum induction furnaces, vacuum electron beam furnace and vacuum furnace smelting and production of C+N ≤ 150-250ppm consumption of high purity ferritic stainless steel 00Cr18Mo2, and 00Cr26Mo1 and 00Cr30Mo2; w/Mo ≥ 4.5% Higher Mo and Mo-NI austenitic stainless steels containing n, for example, developed 00Cr20Ni25Mo4.5Cu, 00Cr18Ni18Mo5 (n), 00Cr25Ni25Mo5N, and in the chemical, petrochemical and marine development in application in solving solid soluble concentrated nitric acid corrosion and intergranular corrosion, 00Cr25Ni20Nb has been developed and several extra low carbon high silicon stainless steel, 80, Super low carbon and on steel in the p content and alpha phase volume strictly control of urea level stainless steel 00Cr18Ni14Mo2 and 00Cr25Ni22Mo2N two species grades development completed, they of Board, and tube, and Rod material, and forging and welding material are in medium urea industrial in the get has application, made has satisfaction of results; due to some special Mills gradually built smelting stainless steel of furnace outside refining equipment, for example AOD (argon oxygen refining furnace), and VOD (vacuum oxygen refining furnace), and has production, China stainless steel smelting technology to a new level. It not only makes the production of low carbon and ultra low carbon stainless steel make it easy, and improve the quality of stainless steel, cost reduction. Due to containing Ti of 18-8 type Cr-Ni Austrian’s body steel exists series shortcomings, beauty, and day, industrial advanced national early in 60 generation will has achieved has by containing Ti stainless steel to General used low carbon, and super low carbon stainless steel of transition, and China is in 1985-1990 years between only vigorously for low carbon, and super low carbon stainless steel of development, and production and application, made has some welcome of progress, for example 1988 end of China low carbon, and super low carbon 18-8 type stainless steel production has accounted for China stainless steel production of 10% You Joh. But compared to stainless steel production, application of advanced countries (such as Japan and the United States and other countries 18-8 Cr-Ni steel containing Ti only about 1.5% of stainless steel production), there is a big gap. 80, China has also carried out a controlled nitrogen (n-0.05%-0.10%) and nitrogen alloying (N>0.10%)-NI austenitic stainless steel developed. Tests showed that n-NI austenitic stainless steel and duplex stainless steel is an invaluable and very useful element. Strengthen the role of nitrogen and lower intergranular corrosion susceptibility of steel, improved corrosion resistance, in particular to improve the pitting-resistance of steel and other mechanisms, in-depth research work being carried out. Several controlled nitrogen and Cr-Ni of nitrogen alloyed austenitic stainless steel project requires the production and application.

Product features
Usually stainless steel pipe has three characteristics: weldability, corrosion resistance, polishability (BQ)
Application requirements for welding performance also varies. Type of cutlery on the welding properties not required generally, even including some kind of enterprise. But most products need good welding properties of raw materials, two types of cutlery, mug, steel pipes, water heaters, drinking fountains, etc.
Corrosion resistance
Most stainless steel products requirements resistance corrosion performance good, stainless steel tube as one or two class tableware, and kitchen, and water heater, and water machine,, some abroad businessman on products also do resistance corrosion performance test: with NACL water solution heating to boiling, a time Hou pour off solution, wash NET drying, said weight loss, to determine by corrosion degree (Note: products polishing Shi, for Emery cloth or sandpaper in the contains Fe of components, will led to test Shi surface appeared rust)
Polishing (BQ)

Stainless steel products generally have polished the processes in production, only a few products, such as water heaters, drinking fountains liner does not require polishing. This requires polishing of the material very well. Factors affecting properties of polished mainly the following points:
① material surface defects. Such as scratches, pits, acid, etc.
② stainless steel raw material issues. Hardness is too low, polishing, it is not easy to throw light (bad BQ), and hardness is too low, the surface appears orange peel phenomenon in deep drawing, thus affecting the BQ. High hardness BQ is relatively good.
③ After deep drawing of product, distortion great regional and RIDGING can make small black spots on the surface, which affects the BQ.

Source: http://www.steel-tubes.com/