There are many types of steel used for sheet metal processing and many varieties of steel grades involved. In order to indicate the grade and specification of the metal material, certain markings are usually made on the material, and the commonly used marking methods include colouring, printing and hanging. Colour-coded markings on metal materials are used to indicate the steel type and steel number, and are painted on the end of the material or on the outside. Steel delivered in bundles should be painted on the end face of the same end, while coils are painted on the outside of the volume. The specific colouring methods are detailed in the relevant standards and can be used to identify steel materials according to their colour code. The table below gives the painted colour marks for common steels.
|Steel Tube Type||Colouring Marks||Steel Tube Type||Colouring Marks|
|05~15||White||Manganese steel||Yellow + Blue|
|20~25||Brown + Green||Silicon-manganese steel||Red + Black|
|20~25||Brown + Green||Chrome steel|
Blue + Yellow
|45~85||White + Brown||W12Cr4V4Mo||One in Brown + One in Yellow|
|15Mn~40Mn||Two in White||W18Cr4V||One in Brown + One in Blue|
|15Mn~40Mn||Two in White Green||W9Cr4V2||Two in Brown|
In the sheet metal production process, it is not enough to identify the steel number alone. As the steel used in production is supplied by the steel mills in accordance with certain size specifications, a reasonable choice of steel species and specifications must be made in order to improve product quality and steel utilisation to reduce production costs.
In addition, sheet metal products often need to be calculated for their theoretical quality in terms of manufacture, transport and lifting, and production cost control.
Varieties and specifications of steel for sheet metal
Depending on the variety of steel used and the shape of the section, steel for sheet metal processing can be divided into four main categories: plates, steel tubes, sections and steel wires. The dimensions and specifications for each category are mainly as follows.
Plate mainly has steel plate, flat steel, patterned steel plate, etc. , plate delivery, its size specifications, thickness allowable deviation should be in line with the corresponding national standards, Appendix A gives the steel plate and steel strip, patterned steel plate and other metal materials size specifications and thickness allowable deviation.
⒈Steel plate. Steel plate specifications are marked according to the thickness of the steel plate, such as often said 24 of the steel plate, refers to the thickness of t = 24mm steel plate. Steel plate is commonly used in the manufacture of pressure vessels, boxes, bodies and steel structural components. There are two main categories of thin steel plates and thick steel plates according to their thickness.
Thin steel plate is a steel plate with a thickness between 0. 2 and 4mm. The width of thin steel plate is 500~1500mm and the length is 1000~4000mm, thin steel plate is also available in rolls. There are two types of thin steel plates: hot rolled thin steel plates and cold rolled thin steel plates. Commonly used in the automotive, electrical, mechanical and other industrial sectors in the manufacture of housing, water tanks, fuel tanks, stamping parts, etc. . Some thin steel plates are used after rolling, pickling, galvanizing, tin plating, and composite thin steel plates with plastic coating on the surface. These thin steel plates are mainly used as stamping parts or components requiring corrosion resistance, such as containers, sinks, ventilation pipes and roofing corrugated sheets.
Thick steel plate is a steel plate with a thickness of 4mm or more. Usually, the steel plate of 4~25mm thickness is called medium plate, the steel plate of 25~60mm thickness is called thick plate, the steel plate of more than 60mm is rolled on the special extra thick rolling mill and is called extra thick steel plate. The width of thick steel plate is 600~3000mm and the length is 4000~12000mm.
Thick steel plates are divided into boiler steel plates, pressure vessel steel plates, marine steel plates, bridge steel plates and special steel plates according to their applications.
The most used in stamping processing is the rolled thin steel plate with the plate thickness below 4mm, according to the national standard GB/T708-2006, the thickness accuracy of steel plate can be divided into four groups of Ⅰ (special advanced finishing surface), Ⅱ (advanced finishing surface), Ⅲ (higher finishing surface), Ⅳ (ordinary finishing surface), each group can be divided into Z (deepest drawing depth), S (deep drawing depth), P (ordinary drawing depth) according to the drawing depth level. P (ordinary deep drawing) three levels. On the stamping process information and drawings, there are special provisions for the representation of materials, such as
Indicates: 08 steel plate, plate size 1. 0mm x 1000mm x 1500mm, ordinary accuracy, advanced finishing surface, deep drawing deep grade cold rolled steel plate.
⒉Flat steel. Flat steel specifications with the width of the flat steel and thickness together marked. Such as 40 × 5 flat steel, that is, the width of 40mm, thickness t = 5mm flat steel.
⒊Patterned steel plate. Patterned steel plate labeling method and the same steel plate, also with thickness, but the thickness of the patterned steel plate does not include the height of the pattern. According to the material, there are ordinary carbon structural steel patterned plate, stainless steel patterned plate and aluminium and aluminium alloy patterned plate and other types; according to the different surface patterns of patterned steel plate, there are mainly diamond-shaped, lentil-shaped and other patterns.
⒋Strip material. Strip material, also known as coil material, is available in a variety of widths and lengths. The width is below 300mm and the length can reach several tens of metres, supplied in rolls, mainly thin material, suitable for the production of large quantities of stamped parts with automatic feeding.
Steel tubes are divided into two categories: seamless steel tubes and seamed steel tubes. Seamless steel pipe is rolled from the whole metal, there is no seam in the section. Seamless steel tubes are made of ordinary carbon steel, high-quality carbon steel and alloy structural steel and many other materials. Seamless steel pipe according to the shape of the section has two kinds of round and shaped, shaped steel pipe has a square, oval, triangular, hexagonal and other shapes. According to the different wall thickness of steel pipe is also divided into thick-walled pipe and thin-walled pipe. Seamless steel tubes are mainly used as geological drilling tubes, cracking tubes for petrochemical industry, boiler tubes and other important components. Cold-drawn seamless steel pipe with an outer diameter of 5 to 200mm, a wall thickness of 0. 25 to 14mm and a length of 1500 to 9000mm.
Seamed steel pipe, also known as welded steel pipe, is bent and welded with steel strips and has two types of galvanization and no galvanization. Galvanised pipes, also known as white iron pipes, have a zinc-plated surface to prevent rusting and are commonly used as low-pressure water pipes, gas pipes and oil pipes. Ungalvanised steel pipes, also known as black iron pipes, are used as ordinary low pressure, non-pressure pipes or general structural parts.
Steel pipe labeling methods are legal metric labeling methods, the inherited imperial method and industry customary nominal diameter labeling three methods, as shown in the figure.
A metric marking method. Steel pipe metric marking is indicated by the outside diameter of the steel pipe d × wall thickness t. For example: steel pipe 159 × 8 said that the outside diameter of the steel pipe size of 159mm, wall thickness of 8mm.
B imperial labeling method. Inch labeling method is indicated by the diameter of the steel pipe. For example: 3/4" steel pipe that the effective diameter of the pipe 3/4". The actual inner diameter d is greater than 3/4" because it takes into account the frictional resistance of the tube wall to the fluid.
C Nominal diameter marking method. The nominal diameter marking method is directly marked with the nominal diameter of the pipe, indicated by D.
Section steel according to the different shape of the section, can be divided into simple section steel and complex section steel. Simple section sections have round steel, square steel, hexagonal steel, flat steel and angle steel, complex section sections have channel steel, Steel beam, steel rails and shaped steel and moulded steel, etc. .
In the production and processing and engineering construction, for the convenience of the section of the representation, can be commonly used in the table below to mark the section of steel.
Commonly used sections are mainly angles, channels and Steel beams, etc. Profiles should generally be marked in detail with the appropriate standard, the profile size specifications and its centre of gravity position can be consulted in the relevant national standards.
⒈Angle steel. Angle steel is divided into equilateral angle and unequal angle steel. Its specifications are marked with the width of the two sides of the angle and the thickness of the angle side together. For example: equilateral angle 63 × 63 × 6 said that the width of the two sides of the angle are 63mm, the thickness of the angle side t = 6mm, see the figure below a; unequal angle 90 × 120 × 8 said that the width of one side of the angle is 120, the width of the other side is 90, the thickness of the angle side t = 8mm, see the figure below b.
⒉Channel steel. The type of channel steel is marked with the value of 1/10 of the high H of the channel steel and the type of web thickness together. For example: channel 16a indicates that the height of the channel H = 160mm and the thickness of the web is common, i. e. type a channel [see figure c below, the specific thickness of the web can be consulted in the corresponding national standard]. In the case of type b channel, this can be expressed as channel 16b. Its web thickness is 2mm thicker than that of type a.
⒊Steel beam. Steel beam specifications are marked the same as channel steel, also marked with the value of H/10, for example: Steel beam 12. 6 indicates the height of Steel beam 126mm ordinary Steel beam, see figure d below.
Steel wire is usually made from hot rolled wire rod (coils), which is cold drawn. Steel wire is widely used, a wide variety of varieties, classification is also relatively complex. Steel wire by chemical composition can be divided into carbon steel wire, alloy steel wire; steel wire by cross-sectional shape can be divided into round steel wire, shaped steel wire (square, rectangular, oval, triangular steel wire, etc. ); steel wire by use can be divided into general purpose steel wire, welding steel wire, nail steel wire, steel wire, spring steel wire, etc. ; steel wire by surface state can be divided into bright steel wire, bright heat-treated steel wire, pickled steel wire, black steel wire, etc. Plated steel wire, etc. ; steel wire can be divided into fine steel wire (0. 1 to 0. 5mm), finer steel wire (0. 5 to 1. 5mm), medium fineness steel wire (1. 5 to 3. 0mm), coarser steel wire (3. 0 to 6. 0mm), coarse steel wire (6. 0 to 8. 0mm) according to size.
Calculation of the theoretical mass of steel for sheet metal
The theoretical mass G of a metal material is calculated by multiplying the cross-sectional area A of the material by the length L and then by the density of the material p. The calculation formula is
G = ALρ/ 1000
G - the theoretical mass of the metallic material, kg.
A - the cross-sectional area of the metallic material, mm², the formula for calculating the cross-sectional area of various steels is given in the table below.
L - the length of the metallic material, m
ρ- the density of the metal material, g/cm³, the table below gives the density of commonly used metal materials.
|Name of steel||Formula for calculating cross-sectional area|
|Square steel with rounded corners||A=a²-0.8584r²|
|Steel plates, Flat bars, Strips||A=at|
|Rounded flat steel||A=at-0.8584r²|
|Round steel, Round coils, Steel wire||A=0.8584d²|
|Steel tubes||A=3. 1416δ(D-δ)|
|Equilateral Angle steel||A=d(2b-d)+0. 2146(r²-2r1²)|
|Unequal Angle steel||A=d(B+b-d)+0. 2146(r²-2r1²)|
|Steel beam||A=hd+2δ(b-d) +0. 8584(r²-2r1²)|
|Channel steel||A= hd+2δ(b-d)+0. 4292(r²-2r1²)|
|Name of material||Density/（g/cm³）||Name of material||Density/（g/cm³）|
|Carbon steel||7.85||Tin bronze||8.70~8.90|
|Cast steel||7.80||Without tin bronze||7.50~8.20|
|Grey cast iron||6.80~7.20||Aluminium for industrial use||2.70|
|Malleable iron||7.20~7.40||Magnesium alloy||0.74~1.81|
|Cemented Carbide (Tungsten)||13.90~14.90||Silicon-steel strip||7.55~7.80|
|High speed steel||8.30~8.70||Tin-based bearing alloys||7.34~7.75|
|Purple Tongue||8.90||Lead-based bearing alloys||9.33~10.67|
In the cold work products, the most widely used and the most applied material is steel plate, in the calculation of the quality of steel plate, because ρ is 7. 85g/cm³, so the area of steel plate A into the above formula, can be obtained from the calculation formula of the quality of steel plate G
G - the theoretical mass of the steel plate, kg.
A - the area of the steel plate, m².
t - the thickness of the steel plate, mm.