1. Stainless steel hot-rolled steel plate
Stainless steel hot-rolled steel sheet is a stainless steel sheet produced by a hot rolling process. Those with a thickness not greater than 3mm are thin plates, and those with a thickness greater than 3mm are thick plates. Used in the manufacture of corrosion-resistant parts, containers and equipment in the chemical, petroleum, machinery, shipbuilding and other industries. Its classification and grades are as follows:
1 . Austenitic steel
(1) 1Cr17Mn6Ni15N; (2) 1Cr18Mn8Ni5N; (3) 1Cr18Ni9; (4) 1Cr18Ni9Si3; (5) 0Cr18Ni9;
(6) 00Cr19Ni10; (7) 0Cr19Ni9N; (8) 0Cr19Ni10NbN; (9) 00Cr18Ni10N; (10) 1Cr18Ni12;
(11) 0Cr23Ni13; (12) 0Cr25Ni20; (13) 0Cr17Ni12Mo2; (14) 00Cr17Ni14Mo2;
(15) 0Cr17Ni12Mo2N; (16) 00Cr17Ni13Mo2N; (17) 1Cr18Ni12Mo2Ti; (18) 0Cr18Ni12Mo2Ti;
(19) 1Cr18Ni12Mo3Ti; (20) 0Cr18Ni12Mo3Ti; (21) 0Cr18Ni12Mo2Cu2;
(22) 00Cr18Ni14Mo2Cu2; (23) 0Cr19Ni13Mo3; (24) 00Cr19Ni13Mo3; (25) 0Cr18Ni16Mo5;
(26) 1Cr18Ni9Ti; (27) 0Cr18Ni10Ti; (28) 0Cr18Ni11Nb; (29) 0Cr18Ni13Si4
2 . Austenitic-ferritic steel
(30) 0Cr26Ni5Mo2; (31) 00Cr18Ni5Mo3Si2;
3. Ferritic steel
(32) 0Cr13Al; (33) 00Cr12; (34) 1Cr15; (35) 1Cr17; (36) 1Cr17Mo; (37) 00Cr17Mo;
(38)00Cr18Mo2; (39)00Cr30Mo2; (40)00Cr27Mo
4. martensitic steel
(41) 1Cr12; (42) 0Cr13; (43); 1Cr13; (44) 2Cr13; (45) 3Cr13; (46) 4Cr13;
(47) 3Cr16; (48) 7Cr17
5. Precipitation hardening steel
2. Stainless steel cold rolled steel plate
Stainless steel cold-rolled steel plate is a stainless steel plate produced by cold-rolling process, the thickness is not more than 3mm is thin plate, the thickness is more than 3mm is thick plate. It is used to make corrosion-resistant parts, petroleum and chemical pipelines, containers, medical equipment, marine equipment, etc. The classification and grades are as follows:
1 . Austenitic steel
In addition to the same as the hot-rolled part (29 types), there are: (1) 2Cr13Mn9Ni4(2)1Cr17Ni7(3) 1Cr17Ni8
2 . Austenitic-ferritic steel
In addition to the same as the hot rolled part (2 types), there are: (1) 1Cr18Ni11Si4AlTi (2) 1Cr21Ni5Ti
3. Ferritic steel
In addition to the same as the hot rolled part (9 types), there are: 00Cr17
4. martensitic steel
In addition to the same as the hot rolled part (8 kinds), there are 1Cr17Ni2
5. Precipitation hardening section steel: same as hot rolled part
3. Introduction to ferrite, austenite and martensite
We all know that solid metals and alloys are all crystals, that is, the atoms in them are arranged according to certain rules, and there are generally three arrangements: body-centered cubic lattice structure, face-centered cubic lattice structure and close-packed hexagonal lattice structure. . Metals are composed of polycrystals, and their polycrystalline structures are formed during the crystallization of the metal. The iron constituting the iron-carbon alloy has two lattice structures: α-iron with body-centered cubic lattice structure below 910 °C, and γ-iron with face-centered cubic lattice structure above 910 °C. If carbon atoms are squeezed into the lattice of iron without destroying the lattice structure of iron, such a substance is called a solid solution. The solid solution formed by dissolving carbon into α-iron is called ferrite. Its ability to dissolve carbon is extremely low, and the maximum solubility does not exceed 0.02%. The solid solution formed by dissolving carbon into γ-iron is called austenite, and its carbon-dissolving ability is high, up to 2%. Austenite is the high temperature phase of iron-carbon alloys.
The austenite formed by steel at high temperature becomes unstable supercooled austenite when it is supercooled below 727 °C. If it is supercooled to below 230 ℃ at a great cooling rate, the carbon atoms in the austenite have no possibility of diffusion, and the austenite will directly transform into a carbon-containing supersaturated α solid solution, called martensite . Due to the supersaturation of carbon content, the strength and hardness of martensite are increased, the plasticity is decreased, and the brittleness is increased.
The corrosion resistance of stainless steel mainly comes from chromium. Experiments have shown that the corrosion resistance of steel will be greatly improved only when the chromium content exceeds 12%. Therefore, the chromium content in stainless steel is generally not less than 12%. Due to the increase of chromium content, it also has a great influence on the structure of steel. When the chromium content is high and the carbon content is low, chromium will balance iron and carbon, and the γ phase area on the figure will shrink or even disappear. This stainless steel is iron The ferrite structure, which does not undergo phase transformation when heated, is called ferritic stainless steel.
When the chromium content is low (but higher than 12%) and the carbon content is high, when the alloy is cooled from high temperature, it is easy to form martensite, so this type of steel is called martensitic stainless steel.
Nickel can expand the γ phase region and make the steel have austenite structure. If the nickel content is high enough that the steel also has an austenitic structure at room temperature, the steel is called austenitic stainless steel.
4. Approximate comparison of stainless steel grades commonly used in my country and Japan
1 . Chart:
Japan (JIS) & China (GB)
2 . After the brand number, press NO. 1 means heat treatment, pickling or similar treatment after hot rolling; NO. 2 means heat treatment, pickling or corresponding treatment after cold rolling; NO. 2B means cold rolling followed by heat treatment, pickling or similar treatment, and finally cold rolling to obtain a suitable finish. Such as 304NO. 1 Stainless steel plate means hot rolled stainless steel plate of grade 304. Another example is 321-2B, which means the cold-rolled stainless steel plate with the grade of 321. The surface is required to be heat-treated after cold-rolling, pickling or similar, and finally cold-rolled to obtain an appropriate finish.
5. the application of stainless steel in various fields
1 . During about 40 years from 1960 to 1999, the output of stainless steel in Western countries soared from 2.15 million tons to 17.28 million tons, an increase of about 8 times, with an average annual growth rate of about 5.5 million tons. 5%. Stainless steel is mainly used in kitchens, home appliances, transportation, construction, and civil engineering. In terms of kitchen utensils, there are mainly washing tanks and electric and gas water heaters, and home appliances mainly include the drum of automatic washing machines. From the viewpoint of environmental protection such as energy saving and recycling, the demand for stainless steel is expected to expand further.
In the field of transportation, there are mainly exhaust systems for railway vehicles and automobiles. The stainless steel used for exhaust systems is about 20-30kg per vehicle, and the annual demand in the world is about 1 million tons. This is the largest application field of stainless steel.
In the construction sector, there has been a recent surge in demand, such as: guards in Singapore MRT stations, using around 5,000 tonnes of stainless steel exterior trim. Another example is Japan after 1980, the stainless steel used in the construction industry has increased by about 4 times, mainly used for roofs, building interior and exterior decoration and structural materials. In the 1980s, 304-type unpainted materials were used as roofing materials in the coastal areas of Japan, and the use of painted stainless steel was gradually changed from the consideration of rust prevention. In the 1990s, ferritic stainless steel with a high corrosion resistance of more than 20% high Cr was developed and used as a roof material, and various surface finishing techniques were developed for aesthetics.
In the field of civil engineering, stainless steel is used for dam suction towers in Japan. In the cold regions of Europe and the United States, in order to prevent the freezing of highways and bridges, it is necessary to sprinkle salt, which accelerates the corrosion of steel bars, so stainless steel steel bars are used. In the roads in North America, about 40 stainless steel rebars have been used in the past 3 years, and the consumption of each place is 200-1000 tons. In the future, stainless steel will make a difference in the market in this field.
2 . The key to expanding the application of stainless steel in the future is environmental protection, long life and the popularity of IT.
Regarding environmental protection, first from the viewpoint of atmospheric environmental protection, the demand for heat-resistant and high-temperature corrosion-resistant stainless steel for high-temperature waste incinerators, LNG power generation devices, and high-efficiency power generation devices using coal to suppress dioxin generation will expand. It is also estimated that the battery casing of fuel cell vehicles, which will be put into practical use in the early 21st century, will also use stainless steel. From the viewpoint of water quality and environmental protection, in water supply and drainage treatment equipment, stainless steel with excellent corrosion resistance will also expand the demand.
Regarding long life, the use of stainless steel is increasing in existing bridges, highways, tunnels and other facilities in Europe, and this trend is expected to spread all over the world. In addition, the lifespan of general residential buildings in Japan is particularly short at 20-30 years, and the disposal of waste materials has become a major problem. With the recent emergence of buildings with a lifespan of 100 years, the demand for materials with excellent durability will grow. From the perspective of global environmental protection, while reducing civil engineering and construction waste, it is necessary to explore how to reduce maintenance costs from the design stage of introducing new concepts.
Regarding the popularization of IT, in the process of IT development and popularization, functional materials play a great role in equipment hardware, and the requirements for high-precision and high-functional materials are very large. For example, in mobile phone and microcomputer components, the high strength, elasticity and non-magnetic properties of stainless steel are flexibly applied, which expands the application of stainless steel. Also in manufacturing equipment for semiconductors and various substrates, stainless steel with good cleanliness and durability plays an important role.
Stainless steel has many excellent properties that other metals do not have, and is a material with excellent durability and recyclability. In the future, stainless steel will be widely used in various fields in response to changes in the times.
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