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I. Classification of steel materials Steel and its classification Steel molten steel produced in a steelmaking furnace is cast into billets, and steel ingots or billets are processed into steel (steel products) by pressure. There are many types of steel, which can be generally divided into four types: type, plate, tube and wire.
1. There are many varieties of steel type steel, which is a solid Steel BAR with a certain cross-sectional shape and size. According to the different shape of the cross section, it is divided into two types: simple and complex. The former include round steel, square steel, flat steel, hexagonal steel and angle steel; the latter includes steel rails, I-beams, channel steels, window frame steels, and profiled steels. Small round steel with diameter of 6.5-9.0mm is called wire rod.
2. The steel plate is a flat steel with a wide aspect ratio and a large surface area. According to the thickness of different thin plate (thickness <4mm), the medium plate (thickness 4-25mm) and thick plate (thickness> 25mm) three. Steel strips are included in the steel sheet.
3, Steel Pipe is a hollow section of long steel. According to its different cross-sectional shape can be divided into round tube, square tube, hexagonal tube and a variety of profiled steel pipe. According to different processing technology, it can be divided into two categories: Seamless Steel Pipe and Welded Pipe.
4, wire steel wire is a cold wire products once again processed products. According to the shape of different round wire, flat wire and triangular steel wire and so on. In addition to direct use of steel wire, it is also used to produce wire ropes, steel wire and other products.
1. Classification of pig iron Iron and steel materials usually refer to iron-carbon alloys, classified according to the size of carbon content, carbon content (mass fraction) greater than 2% for pig iron, less than 2% for steel, carbon content (mass fraction) Less than 0.04% of industrial pure iron.
Classification and classification of pig iron Classification Name Description
1. According to the purpose of use (1) steelmaking pig iron steelmaking pig iron is used for open hearth, converter steelmaking pig iron, generally lower silicon content (less than 1.75%), high sulfur content (less than 0.07%), quality Hard and brittle, fractured white, also known as white iron
(2) Cast pig iron Cast pig iron refers to pig iron used to cast various pig iron castings. Generally, the silicon content is high (up to 3.75%), the sulfur content is slightly lower (less than 0.06%), and the fracture is gray, also called gray. Iron
2. According to chemical composition (1) Ordinary pig iron Ordinary pig iron refers to pig iron that does not contain other alloying elements, such as steel-making pig iron, foundry pig iron, etc.
(2) Special pig iron 1) Natural alloy pig iron - a kind of special pig iron made of iron ore or concentrate containing symbiotic metal and reduced with reducing agent, can be used for steel making and casting
2) Ferro-alloys—specially added with other elements during the iron-making process, and refined into special pig iron containing various alloying elements. There are many varieties, such as ferromanganese, ferrosilicon, ferrochromium, etc., which are one of the raw materials for steelmaking. , can also be used for casting Note: The composition content refers to the mass fraction.
2. Classification of cast iron Classification of cast iron Classification Name Description
1. According to the color of the fracture (1) Gray cast iron Most or all of the carbon in this cast iron is in the form of flake graphite in the free state. Its fracture is dark gray, and has certain mechanical properties and good cutting performance. It is widely used in industry. in
(2) White cast iron White cast iron is an iron-carbon alloy with no or almost no graphite in the structure. Its fracture is bright white, hard and brittle, and cannot be cut. It is rarely used directly in the industry. Mechanical Parts. Because of its high surface hardness and wear resistance, it is also called chilled cast iron or chilled cast iron.
(3)Mock cast iron Cast iron is a kind of cast iron between white cast iron and gray cast iron. Its fractures are gray and white with pitting, poor performance, and are rarely used.
2. According to chemical composition (1) Ordinary cast iron means cast iron that does not contain any alloying elements, such as gray cast iron, malleable cast iron, nodular cast iron, etc.
(2) Alloy cast iron is a kind of advanced cast iron that is prepared by adding some alloying elements to common cast iron to improve certain special properties. Such as various corrosion resistance, heat resistance, wear resistance, special properties of cast iron
3. According to production methods and properties (1) Ordinary gray cast iron See "Grey Cast Iron"
(2) Breeding cast iron This is based on the gray cast iron, using "modified treatment" made of, also known as deteriorating cast iron. Its strength, plasticity and toughness are much better than those of ordinary gray cast iron, and the structure is relatively uniform. Mainly used for manufacturing large-scale castings with high mechanical performance requirements and large changes in section size
(3) Malleable cast iron Malleable cast iron is a white cast iron of a certain composition which is graphitized and annealed. It has higher toughness than gray cast iron and is also called tough cast iron. It is not forged and is often used to make castings subject to impact loading
(4) Ductile Iron Casting iron for short. It is obtained by adding a certain amount of nodularizer and ink agent to the molten iron in the casting to promote the crystallization of spherical graphite. Compared with steel, it has similar properties except steel with lower ductility and toughness. It is an excellent material that combines the advantages of steel and cast iron. It is widely used in mechanical engineering.
(5) Cast Iron with Special Properties This is a kind of cast iron with certain characteristics. According to different uses, it can be divided into wear-resistant cast iron, heat-resistant cast iron, and corrosion-resistant cast iron. Most of them belong to alloy cast iron and are widely used in machinery manufacturing.
3. Classification of steel Classification and classification of steel Classification name Description
1. Chemical composition
(1) Carbon steel Carbon steel is an iron-carbon alloy that contains a small amount of elements such as manganese, silicon, sulfur, and phosphorus in addition to iron and carbon. The carbon steel can be classified according to its carbon content:
1) Low carbon steel - carbon content wc≤0.25%
2) Medium carbon steel - Carbon content wc> 0.25% to 0.60%
3) High-carbon steel - carbon content wc> 0.60%
(2) Alloy steel In order to improve the performance of steel, based on the carbon steel smelting, adding some alloying elements and refining the steel, such as chromium steel, manganese steel, chromium manganese steel, chromium nickel steel. According to the total content of alloying elements, it can be divided into:
1) Low-alloy steel - the total content of alloying elements ≤ 5%
2) Medium alloy steel - the total content of alloying elements 5% to 10%
3) High Alloy Steel - Total Content of Alloying Elements >10%
2. Press smelting equipment
(1) Converter steel Converter steel can be classified into bottom-blowing, side-blown, top-blown and air-blown, and oxygen-blown converter steels; depending on the furnace lining, it can be divided into two types: acidic and alkaline.
(2) Open hearth steel The steel produced by open hearth refining is divided into two types, acidic and basic, depending on the material of the lining material. Generally, the open hearth steel is mostly alkaline.
(3) Electric furnace steel The steels refined by electric furnace include arc furnace steel, induction furnace steel and vacuum induction furnace steel. Industrially mass-produced, alkaline arc furnace steel
3. According to the degree of deoxidation prior to pouring (1) Boiling steel is incompletely deoxidized steel, which causes boiling phenomenon in the ingot mold. Its advantages are less smelting loss, low cost, good surface quality and deep drawability; disadvantages are uneven composition and quality, poor corrosion resistance and mechanical strength, generally used in the rolling of carbon steel structural steel and steel plate
(2) Calorific steel A steel that is completely deoxidized. The molten steel in the ingot mold is sedated during pouring, and there is no boiling phenomenon. The advantage is that the composition and quality are uniform; the disadvantage is that the yield of the metal is low and the cost is high. General alloy steel and high-quality carbon structural steel are killed steel
(3) Semi-static steel Steels with a degree of deoxidation between the killed steel and boiling steel are difficult to control because of production. Current output is less
4. According to the quality of steel
(1) Ordinary Steel Steel contains many impurity elements, sulfur content ws generally ≤ O. 05%, phosphorus content wP ≤ 0.045%, such as carbon structural steel, low alloy structural steel, etc.
(2) High-quality steel steel contains less impurity elements, sulfur and phosphorus content ws, wp, are generally ≤ 0.04%, such as high-quality carbon structural steel, alloy structural steel, carbon tool steel and alloy tool steel, spring steel , bearing steel, etc.
(3) High-quality steel The steel contains very few impurity elements, and the sulphur content is generally ≤O. 03%, phosphorus content wP ≤ 0.035%, such as alloy structural steel and tool steel. High-quality steel is usually marked with “A” or Chinese character “high” behind the steel number for identification
5. According to the use of steel (1) structural steel 1) structural steel for construction and engineering - referred to as construction steel, it refers to steel used for making metal structural parts in buildings, bridges, ships, boilers or other projects. Such as carbon structural steel, low alloy steel, steel bars, etc.
2) Structural Steel for Mechanical Manufacturing - refers to the steel used to make structural parts on mechanical equipment. This kind of steel is basically high-quality steel or high-quality steel, mainly high-quality carbon structural steel, alloy structural steel, easy-cut structural steel, spring steel, rolling bearing steel, etc.
(2) Tool steels are generally used for manufacturing various tools such as carbon tool steels, alloy tool steels, and high-speed tool steels. According to the purpose, it can be divided into cutting tool steel, die steel, measuring steel
(3) Special steels Steels with special properties, such as stainless acid-resistant steels, heat-resistant steels, high-resistance alloys, wear-resistant steels, magnets, etc.
(4) Professional steel This refers to steel for professional use in various industrial sectors, such as automotive steel, agricultural machinery steel, aerospace steel, chemical machinery steel, boiler steel, electrical steel, welding rod steel, etc.
6. According to the manufacturing process (1) cast steel Cast steel is a kind of steel casting produced by casting method. Cast steel is mainly used to make parts that are complex in shape, hard to forge or cut, and require high strength and plasticity.
(2) Forged steel Forged steel refers to various forgings and forgings produced by forging. Forgings are of higher quality than cast steel and can withstand large impact forces. The plasticity, toughness and other mechanical properties are also higher than those of cast steel. Therefore, all important machine parts should use forgings.
(3) Hot-rolled steel Hot-rolled steel refers to various hot-rolled steel products produced by the hot rolling method. Most steels are hot-rolled. Hot-rolling is commonly used to produce large steels such as steel, steel pipes, and steel plates, as well as rolling wires.
(4) Cold-rolled steel Cold-rolled steel refers to various cold-rolled steel materials produced by a cold rolling method. Compared with hot-rolled steel, cold-rolled steel is characterized by its smooth surface, precise dimensions, and good mechanical properties. Cold rolling is commonly used to roll thin plates, strips and steel tubes
(5) Cold drawn steel
Cold-drawn steel refers to various kinds of cold drawn steel produced by cold-drawing method. The characteristics of cold drawn steel are: high precision and good surface quality. Cold drawing is mainly used for the production of steel wire, but also for the production of round and hexagonal steel with diameters below 50mm, and for steel alloys with non-alloy steel, low-alloy steel and alloy steel with diameters up to 76mm. Specification limits (GB/T 13304-1991)
According to the chemical composition of the alloying elements Alloy elements defined content (mass fraction) limit (%)
Non-alloy steel Low alloy steel Alloy steel
A1 <0.10 – ≥0.10
B <0.0005 — ≥0.0005
Bi <0.10 – ≥0.10
Cr <0.30 to nbsp0.30 to <0.50 ≥ 0.50
C0 <0.10 – ≥0.10
Cu <0.10 0.10 to <0.50 ≥ 0.50
Mn <1.00 to 1.00 to <1.40 ≥ 1.4
Mo <0.05 0.05 to <0.10 ≥0.10
Ni <0.30 0.30 to <0.50 ≥ 0.50
Nb <0.02 0.02 to <0.06 ≥ 0.06
Pb (0.40) — ≥0.40
Se <0.10 — ≥0.10
Si <0.50 to nbsp0.50 to <0.90 ≥ 0.90
Te <0.10 – ≥0.10
Tj <0.05 0.05~<0.15 ≥0.13
W < 0.10 - ≥ 0.10
V <0.04 0.04~<0.12 ≥0.12
Zr <0.05 0.05~<0.12 ≥0.12
La line (each element) <0.02 0.02 to <0.05 ≥0.05
Other regulatory elements
(except for S, P, c, and N) <0.05 — ≥0.05
Note: The content of La element can also be the total content of mixed rare earth elements.
The main classification and examples of non-alloy steel (GB/T 13304--1991)
Classified by major characteristics Classified by major quality levels
General quality non-alloyed steels Non-alloyed steels of high quality Special quality non-alloyed steels Non-alloyed steels with the specified maximum strength as the main feature Ordinary quality low-carbon structural steel plates and strips
Low carbon steel grade in GB912
GB2517 RJ216, RJ235,
RJ255, RJ294, RJ343, RJ392 a. Stamped sheet low carbon steel
08A1 in GB5213
08, 10 in GB3276
b. For tin plating, galvanizing, lead plating strips and carbon steel for original panels
GB2518
GB2520
GB4174 All carbon steel grades
GB5065
GB5066
c. Cold-forged and cold-extrusion steels without heat treatment
Non-alloyed steels with a specified minimum strength as the main feature. Carbon structural steel
A and B of Q195 and Q215 in GB700
Class A, Class B of Q235, Class A, B of Q255
Grade, Q275
b. Carbon steel
Q235 in GBl3013
c. Railway Steel
50Q, 55Q a in GBll264. Carbon structural steel
All grades other than ordinary quality grades A and B in GB700 and grades A and B for cold formability and forging special requirements
b. High-quality alkali structural steel
GB699 except for 65Mn, 70Mn, 70, 75, 80, 85 all other brands
YB2009 55Ti, 60Ti, 70Ti a. High quality carbon structural steel
65Mn, 70Mn, in GB699
70,75,80,85 steel
b. Guaranteed hardenability steel
45H in GB5216
c. Thickness-direction performance steel
All non-alloy steels in GB5313
d. Non-alloyed steels with the main characteristic of minimum strength specified for railway steels Q235-A, Q255-A in GBll265
Carbon steel for GBll266 light rail cushion
Carbon steel for GB2826 rail cushion
d. Steel sheet pile steel
e. General quality carbon steel YBl70 of ordinary quality without general heat treatment. Boiler and pressure vessel steel
20g, 22g in GB713
10, 20 in GB3087
20G in GB5310 and GB5311
10, 20G in GB6479
20HP, 15MnHP in GB6653
20R in GB6654
d. Shipbuilding steel
A, B, D, E, AH32, DH32, EH32 in GB712
C10, C20 in GB5312
A, B in GB9945
e. Railway Steel
U71, U74 in GB2585
CL860B grade in GB8601
LG60B and LG65B in GB8602
Carbon steel for YB354 rail fish tail plate
f. Bridge steel
LZ, JZ in 16q GB5068 in YBl68
Class A of LG60 and LG65 in CL60A class GB8602 in GB8601. Aeronautical steels include all aviation-specific non-alloy structural steel grades f. The steel for weapons includes all kinds of non-alloy structural steel grades for weapons. g. Non-alloy steel with non-alloy steel for nuclear pressure vessels with the specified minimum strength as its main characteristic g. Automotive steel
12LW, 15LW in GBll262
45 in GB3088
08Z, 20Z, 25Z in GB9947
h. Chain steel
M15, M20, M30 in YB897
i. Bicycle steel
Z06A1, ZQl95, ZQ215, ZQ235 in GB3644
ZQl95, ZQl95-F, ZQ215, ZQ215-Al, ZQ215-F, ZQ235, ZQ235-A1, ZQ235-F, Z06A1, Z09Mn, Z13Mn, Z17Mn, Z09A1 in GB3645
19Mn in GB3646
19Mn in GB3647
j. Oil and Gas Pipe steel
k. Cast carbon steel for engineering structures
ZG200-400, ZG230-450, ZG270-500, ZG310-570, ZG340-640 in GBl1352
Non-alloyed steels with the specified minimum strength as the main feature ZG200-400H, G230-450H, ZG275-485H in GB7659
1. High-quality non-alloy steel for prestressed and reinforced concrete
Non-alloyed steels with carbon content as the main characteristic a. Ordinary carbon steel wire rod
All carbon steel grades in GB701
b. General purpose low carbon steel wire
All low-carbon steel grades in GB343
c. Tread plate
General quality carbon structural steel in GB3277 a. Welding rod steel
H08, H08A, H08Mn in GBl300,
H08MnA, H15A, H15Mn
H08A in GB3429
H08A in ZBH4405
b. Cold heading steel
BL2, BL3 in GB715
ML10 to ML45 in GB5953
ML15, ML20 in GB5955
ML08 to MLA5 in GB6478
ML25Mn to ML45Mn
c. Tread plate
CB3277 high quality non-alloy steel
d. Wire rod steel
25 to 65 in GB4354-
40Mn~60 MnZBH44003 a. Welding rod steel
H08E in GBl300
H08E, H08C in ZBH4405
b. Carbon spring steel
65~85, 65Mn in GBl222
All non-alloy steels in GB4357
c. Special coil steel
60, 60 Mn, 65, 65 Mn, 70, in GB4355
70Mn, 75, 80, T8MnA, T9A
60-85, 60Mn, 65Mn in ZBH44004,
70Mn, 75Mn, 80Mn, 85Mn
d. Non-alloyed quenched and tempered steel (in accordance with the provisions of 3.1.3.1 in the second part of this standard)
e. Non-alloy hardened steel (in accordance with 3.1.3.1 of Part II of this standard)
f. Flame and induction hardening steels (Unalloyed steels with carbon content as the main characteristic of this standard e. Non-alloyed quenched and tempered steels (except special quality steels)
f. Non-alloy hardened steel (except special quality steel)
g. Non-alloyed spring steel (except for special quality steel) Part 3.1.3.1 of Part 2)
g. Cold upset and cold-extruded steel (in accordance with 3.1.3.1 of the second part of this standard)
Non-alloy free-cutting steel Free-cutting structural steel
Y12, Y12Pb, Y15, in GB8731
Y15Pb, Y20, Y30 Y35, Y45Ca special free-cutting steels require to measure the impact toughness after heat treatment YB685
Y75 in
Non-alloy tool steel a. Carbon tool steel
All grades in GBl298
T12A in YB483
b. Carbon hollow steel
ZKT8 in GBl301
Non-alloyed steels with specified magnetic and electrical properties a. Non-alloy electrical steel plate, with GB2521 silicon-free electrical steel plate, with
b. Non-alloyed electrical steel with specified electrical conductivity (<9s/m). Non-alloyed electrical steel with specified conductivity (≥9s/m)
b. Non-alloy soft magnetic material with specified magnetic properties
DT3 in GB6983, GB6984, GB6985,
DT3A, DT4, DT4A, DT4E, DT4C
F7402-UF7402-V in ZBH72001,
F7402-W
Other non-alloy steel fence steel wire
YTlF, YT2F, YT3, YT4 in GB9971
Major classification and examples of low alloy steel (GB/T13304-1991)
According to the main quality grade classification according to the main characteristics of the ordinary quality of low alloy steel high quality low alloy steel special quality low alloy steel can weld low alloy high strength structural steel e. Low alloy steel for bridges
12Mnq, 12MnVq, 16Mnq, 15MnVNq, 15MnVNq in YBl68
16Mnq, 16MnCuq, 15MnVq, 15MnVNq in YB(T)10
f. Low-alloy steel for bicycles
12Mn, 16Mn in GB3646
12Mn, 16Mn in GB3647
Low alloy weathering steel a. Low Alloy High Weathering Steel
09CuPCrNi-A, 09CuPCrNi-B, 09CUP in GB4171
b. Weldable low alloy weathering steel
16CuCr, 12MnCuCr, 15MnCuCr, 15MnCuCr-QT in GB4172
Low-alloy rebar steel General low-alloy rebar steel
GBl499
20MnSi, 20MnTi, 20MnSiV25MnSi,
20MnNbb
Low alloy steel for railway Low alloy light rail steel
45SiMnP, 50SiMnP a in GBll264. Low alloy heavy rail steel
U71Cu, U71Mn, U70MnSi, U71MnSiCu in GB2585
b. Low-alloy rail steel for cranes
U71Mn in GB3426
c. Railway special-shaped steel
09CuPRE in GB8603
09V Low Alloy Wheel Steel for GB8604
CL45MnSiV in GB8601
Low alloy steel for mine Low alloy structural steel for mine
20MnK, 25MnK, 24Mn2K (hot rolling), 30Mn2K low alloy structural steel for GB3414
20Mn2K in GB3414 (conditioning),
20MnVK, 34SiMnK
Other low-alloy steel Free-cutting structural steel
Low-alloy steel for Y40Mn shave blades in GB8731
Cr03 in GB3527
Classification of alloy steel GB/T 13304--1991)
Main quality level 1 2 3 4 5 6 7 8
High quality alloy steel The main use characteristics of special quality alloy steel Engineering structural steel Other
Steels for engineering structures Steels for mechanical structures (except 4th and 6th) Stainless, corrosion-resistant and heat-resistant steels Tool steels Bearing steels Special physical properties steels Further classification of steel by other characteristics 11
General engineering structure alloy steel 16
Electrician silicon (aluminum) steel (without magnetic permeability requirements) 21
Alloy Steel for Pressure Vessels (Except 4 Types) 3l
Mn(x) steels 41
Martensitic or
42
Ferrite type 411/421 cr(x) steel 51 alloy tool steel
511
Cr(x) steel 6l
High carbon chromium bearing steel 71
Soft magnetic steel
(except 16)
412/422
CrNi(x) steel
12
Alloy rebar steel 32 SiMn(x) steel 512 Ni(x), CrNi(x) steel
413/423
CrNo(X)
CrCo(x) steel
& nbsp17 Alloy steel for railway 22 heat-treated alloy rebar 513 M0(x), CrMo(x) steel 62
Carburizing Bearing Steel 72
Permanent magnet
414/424
CrAI(x)
CrSi(x) steel
13
Alloy steel for geological oil drilling (except 23) 23
Heat treated geology, alloy steel for oil drilling 33
Cr(x) steel 514 v(x),CrV(x) steel 63
Stainless bearing steel
73
Non-magnetic steel
415/425Others 515 w(x), CrW(x)
Steel
34
CrMo(x) steel 431/441/451
CrNi(x) steel
74
High resistance steel and alloy
432/442/452 CrNiMo(x) steel 516
Others 64
High temperature bearing steel
43
Austenite or
44
Austenite-ferritic or
45
Precipitation hardened 52
High speed tool steel 521
WMo steel
35 CrNiMo(x) steel 433/443/453 CrNi+ or Nb steel
24
High manganese steel 522
W Department Steel 65
Non-magnetic bearing steel
434/444/454 CrNiMo+Ti or Nb Steel
36
Ni(x) steel
523
Co steel
435/445/455
CrNi+V, w, co steel
37
B(x) steel 436/446 CrNiSi(x) steel
437 CrMnNi(x) steel
38
other
438
other
Note: (x) indicates that the alloy series also includes other alloying elements, such as cr(x), and Cr steels in addition to Cr steels.
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