1. Brand Q 195, low carbon content, low strength, good plasticity, toughness, machinability and weldability. Used for rolling thin plates and wires. Cold-rolled and hot-rolled steel plates and their galvanized, tinned and plastic composite steel plates are widely used in roof panels, decorative plates, general dust removal pipes, packaging containers, iron drums, instrument shells, switch boxes, protective covers, train carriages and so on. Most of the wires are cold-drawn low-carbon steel wires or galvanized low-carbon steel wires, which are used for binding, tensioning and fixing, or used as steel mesh, rivets and so on.
2. The strength of Q2 15 steel is slightly higher than that of Q 195 steel, and its application is basically the same as Q 195 steel. In addition, it is also widely used for welding steel pipes, galvanized welded pipes, furnace supports, anchor screws, bolts, round nails, wood screws, stamped iron hinges and other hardware parts.
3.Q235 has moderate carbon content, good comprehensive properties, good strength, plasticity and weldability, and is the most widely used steel. It is often rolled into wire or round steel, square steel, flat steel, angle steel, I-beam, channel steel, window frame steel and other profiles, as well as medium-thick steel plates. A large number of buildings and engineering structures are used. Used for manufacturing steel bars or building factories, high-voltage transmission towers, bridges, vehicles, boilers, containers, ships, etc. It is also widely used as mechanical parts with low performance requirements. Grade C and D steels can also be used for some professional steels.
4. The brand Q255 is similar to Q235 in performance, with slightly improved strength and reduced plasticity. Q235 is not as widely used, mainly used for riveting and inspection structures.
5.Q275 brand has high strength, hardness and good wear resistance. Used for manufacturing shafts, agricultural machines and tools, wear-resistant parts, rail joint splints, pads, wheels, rollers, etc.
(II) Main uses of low-alloy high-strength structural steels of various brands
The old standard of low-alloy high-strength structural steel is called low-alloy structural steel, which is also called ordinary low-alloy structural steel.
1.Q295 steel contains only a few alloying elements, and its strength is not high, but it has good plasticity, cold bending, weldability and corrosion resistance. Mainly used in building structures, industrial workshops, low-pressure boilers, medium and low-pressure chemical containers, oil tanks, pipelines, cranes, tractors, vehicles and general engineering structures with low strength requirements.
2.Q345 and Q390 steels have good comprehensive mechanical properties, good weldability, cold and hot workability and corrosion resistance, while C, D and E steels have good low-temperature toughness. It is mainly used for welding high-load structural parts such as ships, boilers, pressure vessels, oil storage tanks, bridges, power station equipment, lifting and transportation machinery.
3.Q420 steel has high strength, especially in normalized or normalized+tempered state. It is mainly used for large welding structural parts such as large ships, bridges, power station equipment, medium and high pressure boilers, high pressure vessels, rolling stock, hoisting machinery and mining machinery.
4.Q460 steel has the highest strength, has high comprehensive mechanical properties in normalized, normalized+tempered or quenched and tempered state, and is completely deoxidized with aluminum, with quality grades of C, D and E, which can ensure good toughness of steel. Used in various large engineering structures and light structures with high strength and heavy load.
(III) Characteristics and uses of high-quality carbon structural steel
High quality carbon structural steel is the abbreviation of carbon structural steel, commonly known as high quality steel. It is steel used to make various machine parts.
1.08 and 08F steels are used for rolling thin plates, deep drawing products, oil drums and high-grade enamel products, and can also be used for manufacturing pipes, washers, carburized and cyanided parts with low core strength requirements and covered electrode.
2. 10 and 10F steel are cold-pressed and deep-drawn products, such as deep-drawn containers and shells below 4 mm. It can also be used to manufacture boiler tubes, oil drum covers, steel belts, steel wires, weldments and mechanical parts.
3. 15 and 15F steels are used to manufacture carburized parts, fasteners, stamping and forging modules and low-load parts without heat treatment, such as bolts, screws, flanges, storage tanks for chemical machinery, steam boilers, etc.
4.20 steel is used for various mechanical parts that require toughness without great stress, such as tie rods, bushings, screws, hooks, etc. It can also be used to manufacture pipes, conduits, etc. Used in non-corrosive medium at 60 atmospheric pressure and below 450℃; It can also be used for carburizing and cyaniding parts with weak core strength, such as shaft sleeves, rollers and shafts of chains, and unimportant gears and sprockets.
5.25 Steel is used as mechanical parts for hot forging and hot stamping in large and medium-sized machinery manufacturing, cyanide parts on metal cutting machine tools, shafts, rollers, connectors, washers, bolts, nuts and other parts with small load, and can also be used as steel castings.
6.30 steel, used for hot forging and ...
Question 2: What do you mean by the brand of steel? Hello, I have been doing mechanical design for many years. Let me make a few agreements based on my own experience.
The most common types are ordinary carbon steel and high-quality carbon steel.
Ordinary carbon steel is A 1 A2 A3 A4 A5 A6, of which A3 is the most commonly used.
The commonly used number of high-quality carbon steel is 35 45 40CR 38crmola to indicate the carbon content.
In addition, there are some steel beams, such as hexagonal rods, angle steels, channel steels, I-beams, light rails, rigid square steels and round steels.
There is also a kind of color steel on the market now.
My answers are relatively simple, which are commonly used in mechanical design. There are no details of these copies.
Question: What does the type of Q235B steel mean? Q235 ordinary carbon structural steel-ordinary steel plate is a kind of steel. Q represents the yield value of this material, and the latter 235 refers to the yield value of this material, which is around 235. And the yield value will decrease with the increase of material thickness. Q235A, Q235B, Q235C, Q235D. This is the classification, which mainly represents the different impact temperatures! The difference between a, b, c and d refers to the difference of impact temperature in their properties. They are: Q235A, indicating no influence; Q235B grade, impact at room temperature of 20 degrees; Q235C level, that is, 0 degree impact; Q235D, that is, -20 degree impact. At different impact temperatures, the impact value is also different. Element content: the sulfur content of a, b, c and d decreases in turn; The phosphorus content of a and b is the same, followed by c and d.
Question 4: What do you mean by the group number and brand number of steel? Specific instructions. Generally, the combination of Chinese phonetic alphabet, chemical element symbol and * * * is used to represent the brand of steel.
Such as: low-alloy high-strength steel features: wear resistance, Chinese pinyin Monet, using the symbol Q.
Carbon structural steel ① consists of Q+ number+quality grade symbol+deoxidation method symbol. For example, Q235 stands for carbon structural steel with a yield point (σs) of 235 MPa.
(2) When necessary, symbols indicating quality grade and deoxidation method can be marked behind the steel grade. The quality grade symbols are a, b, c and d respectively. Deoxidation mode symbol: f stands for boiling steel; B stands for semi-killed steel; Z stands for killed steel; TZ stands for special killed steel, and killed steel can be left unmarked, that is, Z and TZ can be left unmarked. For example, Q235-AF stands for Class A boiling steel.
High-quality carbon structural steel ① The two digits at the beginning of the steel number indicate the carbon content of the steel, which is expressed as a few ten thousandths of the average carbon content. For example, the steel with an average carbon content of 0.45% has a steel grade of "45", not a serial number, so it cannot be read as 45 steel.
(2) High-quality carbon structural steel with high manganese content should be marked with manganese, for example, 50Mn.
(3) Boiling steel, semi-killed steel and special-purpose high-quality carbon structural steel shall be specially marked at the end of the steel grade, such as semi-killed steel with an average carbon content of 0. 1%, and the steel grade is 10b.
The steel grade of carbon tool steel ① is marked with "T" to avoid confusion with other steels.
(2) The number in the steel grade indicates the carbon content, which is expressed as a few thousandths of the average carbon content. For example, "T8" means that the average carbon content is 0.8%.
③ If the manganese content is high, mark "Mn" at the end of the steel grade, such as "T8Mn".
④ The phosphorus and sulfur content of high-quality carbon tool steel is lower than that of ordinary high-quality carbon tool steel, and the letter "A" is added at the end of the steel number to indicate the difference, such as "T8MnA".
Free-cutting steel ① The steel number is marked with "Y" to distinguish it from high-quality carbon structural steel.
② The number after the letter "Y" indicates the carbon content, which is expressed as a few ten thousandths of the average carbon content. For example, the free-cutting steel with an average carbon content of 0.3% has a brand name of "Y30".
③ If the manganese content is high, the steel grade is also marked with "Mn", such as "Y40Mn".
Alloy structural steel ① The two digits at the beginning of the steel number indicate the carbon content of the steel, which is expressed as a few ten thousandths of the average carbon content, such as 40Cr.
② The main alloying elements in steel, except a few microalloyed elements, are generally expressed as a few percent. When the average alloy content is Question 5: The steel model ZG270-500 means the old standard ZG35.
Composition of ZG270-500(ZG35): C-0.4; si-0.5； Mn-0.9； S- less than 0.04; P- less than 0.04. Remaining-less than 1%.
Question: What does Q235 steel grade mean? Q235 is a carbon structural steel, equivalent to A3 and C3 steels in the old standard GB700-79, and is a brand of Russian TOCT. Q in its steel grade stands for yield strength. Usually, this kind of steel is used directly without heat treatment.
Question 7: What brand is the steel bar? Hot rolled ribbed bar for reinforced concrete is short for hot rolled ribbed bar, commonly known as rebar. It is made of low-alloy high-strength structural steel by high-temperature hot rolling, and its cross section is usually.
Ribbed round steel for concrete structure is one of the most widely used steels in civil engineering.
Hot-rolled ribbed bars are divided into ordinary hot-rolled bars and fine-grained hot-rolled bars according to the production process, and are divided into three grades according to the characteristic value of yield strength: 335, 400 and 500.
Common brands of hot-rolled steel bars are: HRB335, HRB400 and HRB500, and the brands are HRB (abbreviation of English hot-rolled ribbed steel bar)+yield strength.
Eigenvalue composition
The brands of fine-grained hot-rolled steel bars are HRBF335, HRBF400 and HRBF500, and the brand name is HRBF (English abbreviation of hot-rolled ribbed steel bar followed by the first word of English "Fine").
Mother)+yield strength eigenvalue.
The applicable brands of seismic structural reinforcement with higher requirements are: HRB335E, HRB400E, HRB500E, HRBF335E, HRBF400E and HRBF500E.
Key indicators
1. Mechanical properties. According to GB 1499.2-2007 "Steel for Reinforced Concrete Part 2: Hot Rolled Ribbed Reinforcement", the yield strength ReL and tensile strength of reinforcement are specified.
The characteristic values of mechanical properties, such as Rm, elongation at break A and maximum total elongation Agt, can be used as the minimum guaranteed values for ex-factory inspection.
The mechanical properties of steel bars in seismic structures should also meet the ratio of measured tensile strength to measured yield strength, and the ratio of measured yield strength to specified yield strength characteristic value, so as to
And the special requirements of maximum total elongation.
2. Process performance. After bending 180 according to the specified bending core diameter, there should be no cracks on the surface of the bending part of the steel bar.
3. Chemical composition. The brand, chemical composition and carbon equivalent of steel bars shall comply with the relevant provisions of GB 1499.2-2007.
4. Weight deviation. The deviation between the actual weight and the theoretical weight of steel bars should not exceed the range specified in GB 1499.2-2007.
5. size. The main indicators include inner diameter, cross rib height, cross rib spacing, curvature or elbow.
6. Surface quality. Steel bars should not have harmful surface defects.
Shopping tips
1. Check the surface quality, smoothness and color of steel bars. Steel surface should be smooth and tidy, with uniform color, bright and uniform dark blue gray, without cracks, scars and folds.
Defects visible to the naked eye, such as the end face of steel bars, should be basically round. Inferior steel bars often have oval end faces, uneven and rough surface colors, and even scars, cracks and folds.
Defect: Iron oxide dander produced during rolling falls off due to knocking or wiping.
2. Check the signs, signs and quality certificates of steel bars. Steel surface should be rolled with brand marks, and the factory name (or trademark) number and diameter (mm) should be rolled in turn.
HRB335, HRB400 and HRB500 are denoted by 3, 4 and 5 respectively, HRB335, HRB400 and HRB500 are denoted by C3, C4 and C5 respectively, HRB335E, HRB400E,
HRB500E is represented by 3E, 4E and 5E respectively, and HRBF335E, HRBF400E and HRBF500E are represented by C3E, C4E and C5E respectively.
Question: What does X42 steel mean? X, the line initials of the pipeline, 42, i.e. 420, stands for the tensile strength of steel >: 420 MPa, which is equivalent to S290, S, the initials of the oil and gas pipeline, and 290 stands for the yield strength >; 290 MPa, tensile strength >; 4 15 MPa.
Question 9: What is the type of Q235-A steel? What does b mean? Yes, B is the symbol of deoxidation mode, which means semi-killed steel.
① It consists of Q+ number+quality grade symbol+deoxygenation method symbol. Its steel grade crown has "Q", which represents the yield point of steel, and the number behind it represents the yield point value in Mpa. For example, Q235 stands for carbon structural steel with a yield point (ss) of 235MPa.
(2) When necessary, symbols indicating quality grade and deoxidation method can be marked behind the steel grade. The quality grade symbols are a, b, c and d respectively. Deoxidation mode symbol: f stands for boiling steel; B stands for semi-killed steel; Z stands for killed steel; TZ stands for special killed steel, and killed steel can be left unmarked, that is, Z and TZ can be left unmarked. For example, Q235-AF stands for Class A boiling steel.
(3) Special-purpose carbon steel, such as bridge steel and marine steel, is basically represented by carbon structural steel, but the letter indicating the purpose is added at the end of the steel number.
Question 10: What is the brand of steel and how is it divided? In China, the classification of steel use is used as the basis of classification, and the representation methods are as follows:
1) carbon structural steel:
Representation method: Q+ number+(quality grade symbol)+(deoxidation method symbol)+(special purpose symbol)
(1) The title of steel grade is "Q", which represents the yield point of steel;
② The number after "q" indicates the yield point value in MPa. For example, Q235 stands for carbon structural steel, and its yield point (σs) is 235 MPa.
(3) When necessary, symbols indicating quality grade and deoxidation method can be marked behind the steel grade.
The quality grade symbols are a, b, c and d respectively.
Deoxidation mode symbol: f stands for boiling steel; B stands for semi-killed steel; Z stands for killed steel; TZ stands for special killed steel, and killed steel can be left unmarked, that is, Z and TZ can be left unmarked. For example, Q235-AF stands for Class A boiling steel.
Special purpose carbon steel: such as bridge steel, marine steel, etc. The representation of carbon structural steel is basically adopted, except that the letter indicating the purpose is attached at the end of the steel number.
2) High quality carbon structural steel
Representation method: number+(symbol of element)+(symbol of deoxidation method)+(symbol of special purpose)
① The two digits at the beginning of the steel grade indicate the carbon content of the steel, which is expressed as a few ten thousandths of the average carbon content. For example, the steel with an average carbon content of 0.45% has a steel grade of "45", not a serial number, so it cannot be read as 45 steel.
(2) High-quality carbon structural steel with high manganese content should be marked with manganese, for example, 50Mn.
(3) Boiling steel, semi-killed steel and special-purpose high-quality carbon structural steel shall be specially marked at the end of the steel grade, such as semi-killed steel with an average carbon content of 0. 1%, and the steel grade is 10b.
3) Carbon tool steel
Representation: letter T+ number+(element symbol)+(quality grade symbol)
① The grade of steel is marked with "T" to avoid confusion with other steels.
(2) The number in the steel grade indicates the carbon content, which is expressed as a few thousandths of the average carbon content. For example, "T8" means that the average carbon content is 0.8%.
③ If the manganese content is high, mark "Mn" at the end of the steel grade, such as "T8Mn".
④ The phosphorus and sulfur content of high-quality carbon tool steel is lower than that of ordinary high-quality carbon tool steel, and the letter "A" is added at the end of the steel number to indicate the difference, such as "T8MnA".
4) Free cutting steel
Representation: letter Y+ number+(element symbol)
① Steel grade is marked with "Y" to distinguish it from high-quality carbon structural steel.
② The number after the letter "Y" indicates the carbon content, which is expressed as a few ten thousandths of the average carbon content. For example, the free-cutting steel with an average carbon content of 0.3% has a brand name of "Y30".
③ If the manganese content is high, the steel grade is also marked with "Mn", such as "Y40Mn".
5) Alloy structural steel
Representation method: (special symbol)+number+symbol of main alloy elements and number+symbol of trace alloy elements+(quality grade symbol)+(special symbol)
① The two digits at the beginning of steel grade indicate the carbon content of steel, which is expressed as a few ten thousandths of the average carbon content, such as 40Cr.
② The main alloying elements in steel, except a few microalloyed elements, are generally expressed as a few percent. When the average alloy content is less than 1.5%, only the element symbol is indicated in the steel grade, but in special cases, the number "1" can be indicated after the element symbol, such as steel grades "12CrMoV" and "12cr 1". When the average content of alloying elements is ≥ 1.5%, ≥2.5%, ≥ 3.5%, ..., the content should be indicated after the element symbol, which can be expressed as 2, 3, 4, etc. For example 18Cr2Ni4WA.
(3) Vanadium V, titanium Ti, aluminum AL, boron B, rare earth re and other alloying elements in steel are all microalloyed elements. Although the content is very low, they should still be marked in the steel grade. For example, in 20MnVB steel, vanadium is 0.07-0. 12% and boron is 0.00 1-0.005%.
④ High-quality steel should be marked with "A" at the end of the steel grade to distinguish it from ordinary high-quality steel.
(5) Alloy structural steel for special purposes, the steel grade is preceded by (or suffixed with) a symbol representing the purpose of the steel grade. For example, 30CrMnSi steel for riveting screws, the steel number is marked as ML30CrMnSi.
6) Low alloy high strength steel
Representation method: (special symbol)+number+symbol of main alloy elements and number+symbol of trace alloy elements+(quality grade symbol)+(special ... >; & gt