About stainless steel knowledge:
A, stainless steel hot-rolled steel plate
Stainless steel hot-rolled steel plate is a stainless steel plate produced by hot rolling process. Thickness is not greater than 3mm for thin plate, thickness greater than 3mm for thick plate. It is used in chemical, petroleum, machinery, shipbuilding and other industries to manufacture corrosion-resistant parts, containers and equipment. 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 type steel
(30) 0Cr26Ni5Mo2; (31) 00Cr18Ni5Mo3Si2;
3. Ferritic type steel
(32) 0Cr13Al ; (33) 00Cr12; (34) 1Cr15; (35) 1Cr17; (36) 1Cr17Mo; (37) 00Cr17Mo; (38) 00Cr18Mo2; (39) 00Cr30Mo2; (40) 00Cr27Mo
4. Maraging-type steel
(41) 1Cr12; ( (42) 0Cr13; (43); 1Cr13; (44) 2Cr13; (45) 3Cr13; (46) 4Cr13; (47) 3Cr16; (48) 7Cr17
5. Precipitation hardening steel
(49) 0Cr17Ni7Al
II. Stainless Steel Cold Rolled Steel Plate
Stainless steel cold-rolled steel plate is a cold rolling process to produce stainless steel plate, the thickness of not more than 3mm for the thin plate, the thickness of more than 3mm for the thick plate. Used to make corrosion-resistant parts, petroleum, chemical pipelines, containers, medical equipment, ship equipment, etc., its classification and grade are as follows:
1. Austenitic steel
In addition to the same as the hot rolled part (29 kinds), there are: (1) 2Cr13Mn9Ni4 (2) 1Cr17Ni7 (3) 1Cr17Ni8
2. Austenitic --Ferrite sections
In addition to the same as the hot rolled section (2 types), there are: (1) 1Cr18Ni11Si4AlTi (2) 1Cr21Ni5Ti
3. Ferritic sections
In addition to the same as the hot rolled section (9 types), there are: 00Cr17
4. martensitic steel
In addition to the same as the hot-rolled portion (8 kinds), there are 1Cr17Ni2
5. precipitation hardening steel: the same as the hot-rolled portion
Third, ferrite, austenite, martensite introduction
We all know that solid metals and alloys are crystals, that is, in its internal atoms are arranged in accordance with a certain law, arranged in a general way, there is a good way to make a solid metal. Arrangement, the arrangement of the way there are generally three that is: body-centered cubic lattice structure, face-centered cubic lattice structure and dense rows of hexagonal lattice structure. Metal is composed of polycrystals, its polycrystalline structure is formed in the process of metal crystallization. The iron that makes up iron-carbon alloys has two lattice structures: α--iron with a body-centered cubic lattice structure below 910°C and Υ--iron with a face-centered cubic lattice structure above 910°C. If carbon atoms squeeze into the lattice of iron without destroying the lattice structure of iron, such a substance is called solid solution. Carbon dissolves into α--Fe to form a solid solution called ferrite, its ability to dissolve carbon is very low, the maximum solubility does not exceed 0.02%. While carbon dissolved to Υ - iron in the formation of solid solution is called austenite, its ability to dissolve carbon is higher, up to 2%. Austenite is the high temperature phase of iron-carbon alloys.
Steel at high temperatures when the formation of austenite, subcooled to below 727 ℃ into an unstable subcooled austenite. Such as a great cooling rate of subcooling to 230 ℃ below, then the carbon atoms in the austenite has no diffusion possibility, austenite will be directly into a carbon oversaturated alpha solid solution, known as martensite. As a result of carbon oversaturation, caused by martensite strength and hardness, plasticity reduction, brittleness increased.
The corrosion resistance of stainless steel is mainly derived from chromium. Experiments have shown that only when the chromium content of more than 12% of the steel corrosion resistance will be greatly improved, therefore, the chromium content of stainless steel are generally not less than 12%. Due to the increase in chromium content, the organization of the steel also has a great impact, when the chromium content is high and the carbon content is very small, chromium will make the iron-carbon equilibrium, the Υ-phase area on the graph shrinks, or even disappears, this stainless steel for the ferrite organizational structure, heating does not occur when the phase change, known as ferrite-type stainless steel.
When the chromium content is low (but higher than 12%), the carbon content is high, the alloy is very easy to form martensite when cooled from a high temperature, so this type of steel is called martensitic stainless steel.
Nickel can extend the Υ-phase region, so that the steel has an austenitic organization. If the nickel content is enough to make the steel at room temperature also has an austenitic structure, the steel is called austenitic stainless steel.