History of stainless steel

The invention of stainless steel is a great achievement in the history of metallurgy in the world. In the early 20th century, l.b.guillet and a.m.portervin were in France from 1909 to 1911. W.giesen found the corrosion resistance of Fe Cr and Fe Cr Ni Alloys in England from 1907 to 1909. In 1908-1911, p.monartz put forward many viewpoints on the theory of rust free and passivation in Germany. The inventors of industrial stainless steel include: h.brearly developed martensitic stainless steel containing 12% - 13% Cr12% in Britain from 1912 to 1913; c.dantsizen developed ferritic stainless steel with cr14% - 16%, C × 0.07%? - 0.15% in the United States from 1911 to 1914; e.maurer and b.strauss developed in Germany from 1912 to 1914?? The austenitic stainless steel with 15% - 40% and Ni < 20%. In 1929, Strauss (b.strauss) obtained the patent of low carbon 18-8 (cr-18%, ni-8%) stainless steel. In order to solve the sensitized intergranular corrosion of 18-8 steel, in 1931, e.houdreuot of Germany invented 18-8 stainless steel containing Ti (equivalent to 1Cr18Ni9Ti or AISI? 321). At the same time, the intergranular corrosion resistance of austenitic stainless steel can be improved obviously when ferrite is found in unieu laboratory in France, thus, γ + α duplex stainless steel is developed. In 1946, r.smithtal of the United States developed martensitic precipitation hardening stainless steel 17-4PH, and then semi austenite precipitation hardening stainless steel 17-7ph and ph15-7mo which have high strength and cold working forming were successively produced. At least, the main steel categories in the stainless steel family, namely martensite, ferrite, austenite, α + γ duplex and precipitation hardening type, are basically complete and continue to the present. Of course, in the 1940s-50's, Cr Mn N and Cr Mn Ni n stainless steel with Ni saving, ultra low carbon (C ≤ 0.03%) austenitic stainless steel; in the 1960s, the appearance of α + γ duplex stainless steel with γ: α close to 1, high purity ferritic stainless steel with c+n ≤ 150ppm and martensitic aging stainless steel appeared. Although it also belongs to the major progress in the field of stainless steel, these new steel categories are still classified into the five categories in essence, but they are still classified into the five categories above Rust steel is only the new development of some steel in specific steel. In stainless steel, in addition to the elements of C, Cr, Ni, according to the requirements of different uses for performance, Mo, Cu, Si, N, Mn, Nb, Ti and other elements are further used to alloy or further reduce the elements of C, Si, Mn, s, P in the steel, and many new steel grades have been developed. For example, to solve the pitting and crevice corrosion of chloride, high purity, high chromium molybdenum ferrite stainless steel 00cr25ni4mo4, 00cr29mo4ni2, The high Cr, Mo and high nitrogen content super austenitic stainless steel, such as 00Cr25Ni7Mo3N, 00cr25ni7mo3cun, etc.; nitrogen control stainless steel which appears to improve the strength and corrosion resistance of low carbon and ultra-low carbon Cr Ni austenitic stainless steel; the super austenitic stainless steel with high Cr Mo and high nitrogen content, which is developed to improve the local corrosion resistance of Cr Ni austenitic stainless steel and inhibit the precipitation of gold intermedium in steel, such as 00cr25ni20m O6cun, 00cr24ni22mo7mn3cun; high silicon (SI-6%) stainless steel developed for smoke resistant nitric acid and strong sulfuric acid (93% - 98%). In addition, some special stainless steel has been produced, such as nuclear power, nitric acid, urea, food grade, etc. According to statistics, there are more than 100 brands that have been included in various standards (including factory marks) worldwide, and more non-standard brands are not included. However, the stainless steel grades produced and widely used in advanced countries are limited to nearly ten grades of martensite, ferrite and austenite.

Except for the former Soviet Union, Eastern Europe and China, the world stainless steel output has reached 11million tons, while in 1950, the world stainless steel output is less than 1 million tons, and the output has increased more than 10 times in 40 years. Since 1970, Japan has surpassed the United States in stainless steel production, leading and has been growing continuously. The production of stainless steel is about 30% - 40% of Cr13 martensitic steel and Cr17 type ferritic steel, while 18-8 Cr Ni austenite steel accounts for 60% - 70%. The output of stainless steel in the world's advanced industrial countries generally accounts for 2.5% to 3.5% of the total steel in China. In stainless steel production, new technologies such as ultra high power electric furnace, refining outside furnace, continuous ingot (including thin slab continuous casting), hot continuous rolling or new type rolling mill, cold continuous rolling, continuous pickling heat treatment and continuous protection atmosphere bright heat treatment, as well as various quality detection methods, have been widely used. Large scale, high speed, continuous and automatic are the main development direction of stainless steel production technology and equipment. The stainless steel materials that can be produced and supplied abroad include: cold rolled sheet with width of 2m, including mirror panel, color plate, pattern plate, coating plate, etc.; hot rolled medium plate with width of more than 3m; hot rolled thick plate with thickness of more than 300mm; diameter of more than 1m and small to 0 1mm seamless pipe and various specifications of welded pipe (maximum diameter up to 2m); thickness of about 0.05mm, width of 1m stainless steel foil. The cold rolled sheet and strip account for about 60% of the stainless steel produced by the United States and Japan??. (about 70% of the total sheet and strip materials); about 4% - 5% of the pipes (of which welding pipes account for about 60% of the output of stainless steel pipes in Japan); wire rod accounts for 8% - 9%; rod and profile account for about 10% - 11%.

Application of stainless steel

1. application of stainless steel in construction industry

In recent years, stainless steel is widely used as building materials. There are many reasons for the more and more extensive use of materials, including better understanding of materials, attempts to update some designs, and the production of a durable and maintenance free structural material.

In the early days, stainless steel was used only in some cases, that is, architects were looking for a new material with special effect when they thought there was no suitable material in the past. In fact, many such occasions, stainless steel has been used for a long time and its effect has been continuously washed on stainless steel for a long time, which makes the manufacturer believe that stainless steel materials are not corrosive even in the condition of high corrosive gas.

Because stainless steel has two characteristics of durability and almost no need to maintain the surface, people pay more attention to its application than ever before. Most of the building materials prices are rising rapidly in a certain proportion, and many materials have risen far more than stainless steel materials. The cost of maintaining and maintaining the structure inside and outside the building in good condition has soared even more dramatically. Today's architects must take all the building into account. If the building needs to be replaced or repaired for a long time, the architect's design is a failure.

In recent years, the walls of swimming pools have been made of stainless steel. The main materials concrete used for a long time need to be repaired and painted every year, especially in the north. The swimming pool constructed with carbon steel and coating also needs a large area of scrubbing and painting every year, both of which increase a considerable use cost of the swimming pool. When the swimming pool is made of stainless steel (304, 2b finish) as side wall, it is easy to scrub, and it can be cleaned quickly with water and soap. Nowadays, the pool is usually made of stainless steel trough wall and mixed earth pool bottom, and concrete is mainly used for anti slip.

Some buildings are made of 304 type, 8 grade mirror polished stainless steel. The stainless steel plates connected with each other are polished and colored to make the walls have consistent color fading and reflective properties. To prevent oil scale, the exposed part (antler foot) of large area stainless steel plate is installed in a thick interlayer composed of galvanized plate and compression plate. Polished stainless steel plate is connected and fixed with galvanized steel plate with epoxy resin as binder.

The soft properties of dry stainless steel can be obtained, which may be used as roof covering material on the right. Because this material is easy to form and durable and beautiful, many architects choose stainless steel as not only a protective layer, but as a part of the overall design.

Some buildings (indoor skating rink pipes) use stainless steel to build the roof of the Yongping overlapping layer, which not only makes the building beautiful and generous from the design point of view, but also makes the indoor skating season prolonged due to the reflective effect of the stainless steel surface, and the rabbit will take unreasonable investment.

For some special structures, many problems are often solved by using stainless steel. For example, there is an automobile garage, which is designed to have not only protective effect on parking vehicles but also good ventilation effect on exhaust gas; meanwhile, it can also make a certain degree of sunlight enter the garage, and the material selection is durable and need not be maintained. To meet the above requirements, the designer selects 6 * 10In (15 * 25cm) 201 stainless steel grid plate, which is fixed on the vertical column, so as to make the internal and external staggered layout overlap. To enhance the juice setting effect of the building, floating surface finish is adopted on the staggered outer grid plate, and the outer row column grid plate adopts ordinary 2B finish, and all the inner grids are 2D gloss. This change of the pattern of lending makes the garage have a vivid appearance.

For the roof structure of a building, the service life and appearance of a building should be paid equal attention. In the restaurant of the airport, in order to make the roof beautiful, the exhaust fans are covered with stainless steel plate. When selecting covering materials, the non reflective properties of the materials are also emphasized. The village material selected is 304 stainless steel, rough polishing, low reflection, and grade 6 finish. Special attention should be paid to the selection of the light sell, especially because of glare, which prevents the pilot from seeing the aircraft when landing at the destination.

Stainless steel is used in the internal and external building of the office hall. The building measures are made of stainless steel curtain wall. The columns at the entrance of the building are covered with stainless steel plates, and the purification devices of all windows on the front of the building are covered with stainless steel.

The flower free board on the rest hall of the office building is made of stainless steel plate with relief. The floating convex part of stainless steel sheet is made by using the male and female die

Stainless steel not only has long service life, but also is a good material for making convex structure. This can strengthen the modeling beauty of buildings, so it is often the main sign of square.

Another example of stainless steel used as a main material for outdoor art terminal buildings is the famous arch bridge on the river.

Stainless steel materials can be selected at will. It has many different strength weight ratios to meet the requirements of various building structures. In addition, different grades of surface finish also provide a range of choices for various building facilities to meet the actual needs. The bold idea of architects will make stainless steel more and more widely used in the construction industry.

2. application of stainless steel in marine equipment

Various types of stainless steel are increasingly widely and successfully used in various marine environments. It is necessary to point out that the stainless steel in seawater needs complex anticorrosion engineering technology and a large amount of investment in order to avoid corrosion for a long time. Austenite and martensitic stainless steel have been used for long time in Superheater pipes and turbine blades on marine power plants. It is not easy to keep the chloride content low in these devices, because the application technology of marine power plant is not different from the basic principle of general power generation device. Stainless steel is also being used in large capacity chemical vessels on ocean going commercial ships, and its use is in some ways different from that of onshore chemical plants.

Most stainless steel grades can be used in marine conditions and satisfactory results can be obtained, but different grades are sensitive to stress corrosion cracking. Martensitic steel represented by 410 and ferritic steel, which is representative of 430, will rust in months under ocean conditions. This uniform corrosion can be removed by mechanical grinding. The more popular stainless steel is austenitic stainless steel because it has strong corrosion resistance (except for stress corrosion cracking). As time goes on, austenitic stainless steel will also blacken. If for aesthetic or other reasons, this blackening can also be removed by grinding. Stainless steel rarely produces even rust candle in seawater, so it is not necessary to worry about it in practical use.

Tugboats on the propeller ocean and thrusters on other ships can be made of cast stainless steel cf-8 (equivalent to dry type 304 stainless steel). When the ship is not sailing, the main shaft of the propeller passes through the bearing to the hull, forming a conductive metal circuit. The casting thruster with 410 type stainless steel is often used and widely used in other fields, such as ice breaker.

With the development of modern stainless steel technology, the compound austenite ferrite stainless steel 20cr-8ni-3.5mo has been used to cast large propellers (weighing 3000kg) on ocean giant wheels.

Ships often working in ports are especially vulnerable to damage of thrusters due to logs or other floating bodies on the sea. Therefore, it is a problem worthy of attention that the propeller made of austenitic stainless steel can be repaired by straightening or welding.

The pump has long observed that centrifugal pump can show certain reliability if stainless steel components are used under the condition of seawater operation. In the seawater which keeps flowing, it is not any problem to use cf-8m cast stainless steel impeller (its composition is equivalent to 316 type stainless steel) and 316 stainless steel as the main shaft. When the pump stops working, crevice corrosion and point corrosion are likely to become serious problems. But if it is used to make a pump box with a relatively large wall thickness with relatively active and rusty cast iron, the cast iron can play a cathodic protection role in the shutdown time. When the pump works, the cathodic protection of cast iron box can polarize the lower rust steel, but the flowing water dimension needs the cathodic protection. In addition, pumps that work for a long time may be protected by alternate use, sometimes sea water is replaced with fresh water.

Bulk containers stainless steel has been used as bulk containers in cargo, to load liquefied natural gas (LNG), chemicals, beverages, etc. The container containing LNG in freight is used to 304L stainless steel, which is not designed to resist corrosion but to consider the mechanical properties under low temperature.

For containers of marine chemicals, stainless steel is mainly used to consider its corrosion resistance, which is different from the storage and transportation of onshore chemicals. If the vessel is a general irregular cargo ship, the container carrying chemical products can also transport any items, from acetic acid, slurry to xylene. 316L stainless steel is generally used as valve, freight pump, pipe cover, heating coil and container itself. The vessel can be made of integral stainless steel or a layer of stainless steel plate with 0.06-0.08in (1.5-2.0mm) coated with carbon steel. Before use, the plates must be carefully inspected for defects and thoroughly cleaned and passivated.