With more than 30 years of casting history, Wenzhou Longzhu Industrial Co., Ltd. has a large number of experienced casting engineers and technicians. We can produce castings of various sizes, shapes and materials according to the drawings provided by customers, especially in the field of valve castings. Cooperate with Fortune 500 companies for many years.
GS-C251.0619,WCB.WCC,LCB,LCC,LC3,4C,4D,WC6,C5,C12, C12A,CA15，CF3,CF8(-196’C),CF3M,CF8M,CF8C,CD4MCu,CK3MC uN,ZG200-400,ZG230-450,ZG270-500,2G40Cr1,ZG20CrM0.2G15C r1Mo1V,ZG35Cr1MO.ZG16CrMOG(1Cr5Mo),ZG1Cr13,ZGOCr18Ni9 Ti.5A.KmTB Cr26.4A
Resin sand casting, etc.
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Tel： 0086-0577-86621768 Fax： 0086-0577-86621935
Address ： No.19 Longyong Road.Xiongxin Village. Longwan,Wenzhou,Zhejiang,China
Stainless steel castings are classified by chemical composition as Cr stainless steel, Cr stainless steel and Ni stainless steel. The main factors affecting the corrosion function of stainless steel are C content and separated carbides, so the lower the C content of corrosion-resistant stainless steel, the better, generally C 0.08%. However, the high-temperature mechanical function of heat-resistant steel depends on the stable carbide deposition phase in its arrangement, so the C content of heat-resistant steel is higher, generally more than 0.20%.
According to metallographic arrangement, stainless steels are classified as ferrite stainless steel, martensitic stainless steel, austenitic stainless steel and duplex (ferrite in austenite matrix) stainless steel:
(1) Ferrite stainless steel
With chromium as the main alloy element, the content of Cr is generally between 13% and 30%. Excellent ability to resist corrosion of oxidizing medium and oxidation of air at high temperature can also be used as heat-resistant steel. The welding function of this kind of steel is poor. When the content of chromium is more than 16%, the as-cast arrangement is rough. The brittle phase and phase will appear between 400-525 and 550-700 for a long time, which will make the steel brittle. The brittleness at 475 C is related to the ordering of ferrite containing Cr. The brittleness of brittle phase and phase at 475 C can be improved by heating above 475 C and then cooling rapidly. Room temperature brittleness and brittleness of heat affected zone after welding are also one of the basic problems of ferrites stainless steel, which can be improved by vacuum refining, microelements (such as boron, rare earth and calcium) or austenite elements (such as Ni, Mu, N, Cu, etc.). In order to improve the mechanical function of weld zone and heat-affected zone, a small number of Ti and Nb are usually added to prevent grain growth in heat-affected zone. Commonly used ferrites steels are ZGCr17 and ZGCr28. This kind of steel has low impact toughness and is replaced by austenitic stainless steel with high nickel content in many cases. Ferrite steels containing more than 2% Ni and 0.15% N have excellent impact properties.
(2) Martensitic stainless steel
Martensitic stainless steel includes martensitic stainless steel and deposition hardening stainless steel. In engineering application, mechanical function is the primary purpose. Although such steels have excellent corrosion resistance in atmospheric and mild corrosive media (such as water and some organic media), their corrosion function is often not considered as an inspection item. The scale of chemical composition is: Cr13%-17%, Ni2%-6%, C ; 0.06%. In the metallographic arrangement, the low carbon lath martensitic is the most important. Therefore, it has mechanical function; strength target is more than twice that of austenitic stainless steel, together with outstanding technological function, especially welding function. Therefore, it occupies an extremely important position in the use of important projects and is an important branch in the field of cast stainless steel.
(3) Austenitic stainless steel
Austenitic stainless steel can be divided into four groups, namely, Cr Ni Mo system, Cr Ni Cu or Cr Ni Mo Cu system, Cr Mn N system and Cr Ni Mn N system. The chromium-nickel system is represented by the famous "18-8;. In order to improve the corrosion resistance of sulfuric acid, the systems of Cr Ni Mo, Cr Ni Cu, Cr Ni Mo Cu take part in 2% - 3% molybdenum and copper (or both) on the basis of the system of Cr Ni, but molybdenum is a ferrite constituent element. In order to ensure austenitization, the content of Ni should be properly added after adding molybdenum. The Cr-Mn-N system is an alloy for saving Ni. When the content of Cr is more than 15%, the ideal austenite arrangement can not be achieved by taking part alone. It is necessary to take part in 0.2% - 0.3% nitrogen, and it is necessary to take part in more than 0.35% nitrogen to get a single austenite. Owing to the defects of porosity and porosity in castings caused by excessive N content, single austenite can be obtained by adding appropriate N and a small amount of N i, which presents a system of Cr-Ni-Mn-N. Of course, in order to obtain austenite and ferrite multiphase arrangement, it is not necessary to participate in more N and Ni.
(4) Austenite-ferrite duplex stainless steel
The metallographic arrangement of multiphase steels usually contains 5% - 40% ferrite to improve the weld ability, strength and stress corrosion resistance of alloys. For example, Cr28% - Ni10% - C0.30% high carbon high chromium alloy steel, with outstanding ability of sulfuric acid corrosion resistance, can be used for casting. The controllable ferrite section steel developed on this basis has high strength and excellent stress corrosion resistance in sulphate. It is often used in petroleum industry equipment.