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.
Sales manager： Mrs.peng E-mail: email@example.com
Tel： 0086-0577-86621768 Fax： 0086-0577-86621935
Address ： No.19 Longyong Road.Xiongxin Village. Longwan,Wenzhou,Zhejiang,China
The main feature of this steel grade is that it has significantly better corrosion resistance in different corrosive environments than carbon steel and other common low alloy steels. However, alloying elements added to improve the corrosion resistance of steel. The strength of the steel is often increased while the toughness and weldability are deteriorated. This research on low-alloy corrosion-resistant steel has increased many difficulties, and its development, application and development have been hindered. Therefore, although the research on low-alloy corrosion-resistant steel has been more than half a century old, it has not yet formed a complete system. In development.
There is no uniform classification standard for this steel grade. According to its corrosion resistance characteristics and application fields, it can be divided into atmospheric corrosion resistant low alloy steel, seawater corrosion resistant low alloy steel, salt resistant halogen corrosion low alloy steel, sulfide resistant stress corrosion low alloy steel. , anti-hydrogen corrosion low alloy steel and anti-sulfate dew point corrosion low alloy steel.
Resistance to atmospheric corrosion Low alloy steel is resistant to atmospheric corrosion steel, also known as weathering steel. The experimental study on atmospheric corrosion of steel began in the early 20th century. In 1916, the American Society for Testing and Materials conducted atmospheric corrosion tests on 260 test steels under different atmospheric conditions. The first thing that was confirmed was the anti-atmospheric corrosion effect of copper in steel. Subsequently, the corresponding effect of phosphorus in steel on corrosion resistance was further confirmed. In 1929, the US Steel Company conducted atmospheric corrosion tests on about 300 types of steel, and developed the world's first copper-phosphorus-chromium-nickel-based atmospheric corrosion-resistant steel, named Cor-Ten. The main alloying elements contained in the steel are copper, phosphorus, chromium and nickel, which are only a few tenths of a percent, but their corrosion resistance is several times that of carbon steel, so they are widely used in countries all over the world. Applications. Subsequently, countries have carried out the imitation and improvement of cor-Ten steel. A number of low alloy steels resistant to atmospheric corrosion have been developed.
The development of China's atmospheric corrosion resistant steel is mainly based on domestic resource conditions, starting with copper-containing steel. The 16Mncu, which was prototyped in 1964, was first applied to tankers, bridges and vehicles. So far, many brands have been put into production. In addition to copper-containing steel, a series of steels containing phosphorus and manganese copper have also been developed.
The grades are resistant to atmospheric corrosion. Low-alloy steels have many grades, but most of them contain copper and phosphorus. For example, copper-phosphorus-chromium-nickel-based cor-Ten steels in the United States. Phosphorus-copper-nickel-based steels are removed from the series of steels. (eg BS968 (chromium-copper-nickel-manganese) in the UK, NM (chromium-nickel-copper-copper-titanium) in the former Soviet Union, and 15XCHπ (chromium-silico-nickel-copper), etc. Phosphorus-copper-based steels based on Cor-Ten steel, dephosphorized and nickel, Such as Japan's SMA_41A, B, C (chromium copper) and the United States cor-TenB (chromium copper vanadium), etc. China's manganese-copper steel and phosphorus-based steel developed in combination with national resources. The former has 16 manganese copper, 10 manganese copper Steel such as silicon, 09-manganese-copper-titanium, and 15-manganese-copper. The latter has steels such as phosphonium, phosphorus vanadium, and phosphorus rare earth.
Corrosion characteristics Carbon steel is prone to corrosion in the atmosphere, and its corrosion rate is highly dependent on environmental factors. The corrosion rate in the rural field atmosphere with slight pollution degree is slow. In the industrial atmosphere, due to the increase of pollutant components such as SOz, H2S, HN()3, CO2, N0 and HCl, under the promotion of moisture, Corrosion rate is 1 to 2 times higher than that of rural field environment; in the marine atmosphere, particles containing chloride (such as NaCl, MgCl2, etc.) fall on the steel surface with sea fog, forming a wet film of electrolyte, which aggravates corrosion. It makes the corrosion rate more serious than the industrial atmosphere.
In order to reduce the loss of atmospheric corrosion, a large amount of experimental work has been carried out in adding alloying elements to steel to improve the corrosion resistance of steel, and various low-alloy steels resistant to atmospheric corrosion have been developed.
The role of alloying elements Carbon steel initially develops rapidly in the atmospheric environment. However, after the rust layer is formed on the steel surface, the rust layer plays a protective role, which slows down the corrosion rate, but because the rust layer is loose and porous, Poor adhesion to steel surfaces. Easy to peel off to further accelerate the corrosion rate.
When the steel contains alloying elements with good corrosion resistance such as copper, phosphorus, chromium, molybdenum and nickel, these alloying elements can be concentrated in the rust layer, promote the formation of the amorphous rust layer, improve the structure of the rust layer, and improve the structure. Density and adhesion to the steel surface enhances the isolation from the atmosphere, which slows down the corrosion rate and improves the corrosion resistance of the steel.
Among the above alloying elements, copper is an alloying element which improves the atmospheric corrosion resistance of steel. Steels containing 0.2% to 0.5% copper have exhibited significant corrosion resistance in the atmosphere. The mechanism of the mechanism is different. The former Soviet Union Toma Xiaofu (ToMA Mountain 0B) and others believe that the cathode contact between the steel and the copper precipitated on the surface can promote the anodization of the steel and form a protective rust layer. . It has also been suggested that copper forms a barrier layer that is strongly bonded to the substrate with Cu0 as a main component between the substrate and the rust layer. It has also been suggested that alloying elements such as copper and phosphorus change the hygroscopicity of the rust layer, thereby increasing the critical humidity. Therefore, it is beneficial to improve the corrosion resistance of steel.
Phosphorus plays a special role in improving atmospheric corrosion resistance in steel, which may be related to the unique effect of phosphorus on the formation of amorphous rust layers. When phosphorus and copper are added to steel at the same time, the composite effect is more significant. For example, cor-Ten steel in the United States is composed of chromium and nickel on the basis of copper-phosphorus.
Chromium has a significant effect in improving the passivation ability of steel. When chromium and copper coexist in steel, the effect is more pronounced.
The corrosion resistance of molybdenum is also remarkable. In copper-phosphorus steel, the effect of adding molybdenum is more obvious than that of chromium and nickel. Its role is mainly to improve the properties of the rust layer, but also to promote the formation of amorphous oxide rust layer.
Nickel is mainly used when it is added together with other alloying elements, which plays an advantageous role in improving the structure of the rust layer.
Silicon is mainly concentrated on the steel surface to improve the stability of the rust layer and improve corrosion resistance. Especially in the environment with stress, it can hinder the process of stress corrosion cracking of steel.