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(1) General terms
① delivery status
Refers to the delivery of the final product or final heat treatment of plastic deformation state. Generally not heat-treated hot-rolled or cold drawn, said delivery (rolled) state or manufactured state; after delivery of the said heat treatment state, or under the category called normalizing heat treatment (normalization), quenching, solution, annealing state. Order, the delivery status required in the contract.
② the actual weight of shipment or delivery according to theoretical weight
Actual weight - delivery, the weight of their products is based on weight (weighing) the weight of delivery;
Theoretical weight - delivery, the weight of their products is based on nominal size steel weight calculated. The formula is as follows (theoretical weight required by the delivery person is required in the contract):
Theoretical weight per meter of pipe (steel density 7.85kg/dm3) formula:
W = 0.02466 (D-S) S
The formula: W-tube theoretical weight per meter, kg / m;
D-pipe nominal diameter, mm;
S-pipe nominal wall thickness, mm.
③ guarantee conditions
The provisions of the current standard test items and to ensure compliance with the standard specification, called the guarantee conditions. Ensure that the terms be divided into:
A, the basic guarantee conditions (also known as a necessary condition). Regardless of whether the customers in the contract. Standards required by the provisions of the inspection, and to ensure test results meet the standard requirements.uch as chemical composition, mechanical properties, size deviation, surface quality and inspection, pressure test or flattening or flaring process performance such experiments are a necessary condition.
B, the agreement guarantees conditions: standard conditions, in addition to the basic guarantees, there are "demand-side requirements based upon mutual agreement of supply and demand, and in the contract note? Quot; or" When the demand side requirements ... ... should be in the contract note that "; also customers, the basic guarantee of the standard conditions of tightening the requirements (such as composition, mechanical properties, size deviation, etc.) or by test items (such as pipe ovality, wall thickness of inequality). the above terms and requirements in order, by the supply and demand by the two sides signed the agreement and supply technology in the contract. Therefore, these conditions also known as the guarantee conditions of the agreement. there is an agreement to ensure the conditions of the products, generally have to follow suit.
④ approved
Standard in the "batch" refers to a test unit, the inspection lot. If approved delivery unit group, said the consignments. When a large volume delivery, a delivery batch can consist of several inspection lot; when the delivery volume is low, an inspection lot can be divided into several consignments.
"Batch" is usually composed of the following provisions (see the standard):
A, each batch should be the same grade (steel grade), the same furnace (pot) of the mother or the same heat number, the same specifications and the same heat treatment (furnace) of the steel composition.
B, for high quality carbon steel pipe, fluid pipe, can be different furnace (pot) of the same grade, same size and the same heat treatment (furnace) of the steel composition.
C, each consignment should be the same grade welded steel pipe (steel grade), composed of the same size of pipe.
⑤ high quality steel and high-quality steel
In GB/T699-1999 and GB/T3077-1999 standards, with the back of his trademark "A" character who, for the high quality steel, contrary to the general high quality steel.
High quality steel in the following part or all of superior quality steel:
A, narrowing the range of ingredients;
B, to reduce the harmful elements (such as sulfur, phosphorus, copper) content;
C, to ensure high purity (which requires less non-metallic inclusion content);
D, to ensure high mechanical properties and processing properties.
⑥ vertical and horizontal
Standard said longitudinal direction is parallel with the processing (ie processing along the direction of) persons; horizontal direction is perpendicular with the processing (processing the direction of the tube axis). Impact work to do experiment, the longitudinal sample and processing due to the direction of vertical fracture. It is called horizontal fracture; transverse fracture of the sample parallel to the direction for and processing, so that vertical fracture.
(2) steel shape, size, terms
① nominal size and actual size
A, nominal size: the name specified in the standard size, is the users and manufacturers hope to achieve the ideal size is specified in the contract order size.
B, actual size: the production obtained during the actual size, the dimensions are greater than or less than the nominal size. This is greater than or less than the nominal size of the phenomenon is known as bias.
② bias and tolerance
A, deviation: in the production process, because the actual size is difficult to achieve nominal size requirements that are greater than or less than the nominal size, so the standard set forth in the actual size and nominal size to allow a difference between. Difference is called the positive bias is positive, the difference is called negative bias is negative.
B, Tolerance: standard requires positive and negative deviation of absolute value and is called tolerance, also called "tolerance zones."
Bias is directional, that is "positive" or "negative," said; tolerance is not directional, so the deviation is called "positive tolerance" or "negative tolerance", it is called is wrong.
③ delivery length
Delivery length or the length of the contract, also known as the length of user requirements. Standard delivery length on the following provisions:
A, usually the length (also known as non-cut-length): Where the length of the standard within the prescribed length and no fixed length request, are referred to as usual length. Standard requirements such as structural pipe: hot rolled (extrusion, expansion) tube 3000mm ~ 12000mm; cold drawn (rolled) steel 2000mmm ~ 10500mm.
B, Length Length: Length length should be within the usual length, is required by the contract size of a fixed length. However, the actual operation are cut out absolutely definite length is unlikely, therefore, the standard length of the cut-sets are allowed deviation.
Structural control standards:
Production cut-length tube become useful than the usual length of the tube decreased more, manufacturers fare increase is a reasonable request. Enterprises are not the same rate of increase is generally based on the increase for the base price about 10%.
C, fold-foot length: the length times the scale length should be typically within the contract should specify the length of a single double length and composition of the total length of a multiple (such as 3000mm × 3, or 3 multiples of 3000mm total length of 9000mm). Practice, should be based on the total length to allow positive deviation with 20mm, plus one times the foot length of each incision should be left margin. Structural tube, and the provisions of left incision margin: ≤ 159mm diameter was 5 ~ 10mm; diameter> 159mm for the 10 ~ 15mm. If the standard deviation of no-fold-foot length and cut margin requirements should be negotiations between supply and demand in the contract. Times as long with the definite length scale, as producers will bring a significant reduction in finished product rate, so producers proposed fare increase is justified, the charge increases the rate of increase with the length of the same Length.
D, Scope Length: length range within the usual length, when the user requests a fixed range of length which is required in the contract. For example: normally a length of 3000 ~ 12000mm, while the range of cut-length 6000 ~ 8000mm or 8000 ~ 10000mm. Visible range longer than the length of fixed length and double length requirements relaxed, but a lot of tightening than the usual length, would become useful to the producers to bring the rate lower. So manufacturers proposed fee increases are justified, the tariff increases on the general increase in the base price of around 4%.
④ uneven thickness
Not the same throughout the pipe wall thickness, in its cross-sectional and longitudinal tube wall thickness varies, on an objective phenomenon that is uneven wall thickness. In order to control this heterogeneity, in some provisions of the wall thickness steel pipe standard indicators of inequality allows the general wall thickness tolerance shall not exceed 80% (after consultation by the implementation of supply and demand sides).
⑤ ellipticity
In the circular cross section steel tube outer diameter ranging from the existence of the phenomenon, that there is not necessarily perpendicular to each other the maximum and minimum diameter of the outer diameter of the maximum diameter and minimum diameter shall be the difference between the ellipticity (or not roundness). In order to control the ellipticity, and some steel standard specifies allowable ellipticity index, the general provisions of the diameter tolerance of not more than 80% (after consultation by the implementation of supply and demand sides).
⑥ curvature
Length of steel pipe in the direction of a curve-shaped, with figures expressed its curve is called the degree of curvature. Curvature specified in the standards are generally divided into the following two:
A, the local curvature: with a meter ruler by the largest amount of bend in the pipe, measure the string height (mm), namely the local curvature values, in units of mm / m, said methods such as 2.5mm / m . The method is also applicable to pipe end curvature.
B, full total curvature: with a string, tighten the two ends from the tube to measure the maximum chord pipe bend (mm), and degree of conversion growth (in meters) of the percentage, that is, the direction of pipe length The full curvature.
For example: pipe length is 8m, the measured maximum chord height 30mm, the curvature of the canal should be:
0.03 ÷ 8m × 100% = 0.375%
⑦ difference sizes
Dimensional tolerance or call dimensions beyond the standard deviations. Here the "size" mainly refers to steel tube outer diameter and wall thickness. It was the size tolerance is usually used to call "tolerance excess", which equate to bias and tolerance is not rigorous, it is called, should be called the "deviation bounds." Deviation here may be "positive", it may be "negative", and rarely in the same batch of steel in a "positive and negative" deviation bounds of the phenomenon.
(3) The term chemical analysis
Steel is the relationship between the chemical composition of steel quality and end-use performance is one important factor is the preparation of steel and, ultimately, the main basis for product heat treatment. Therefore, the technical requirements of the standard steel parts, are often the first application of the provisions of the grades of steel (steel grade) and its chemical composition, and the inclusion of standards in tabular form, is a manufacturer and customer acceptance of chemical composition of steel and steel products an important basis.
① steel melting components .The general standard set forth in the chemical composition i.e. melting components. It refers to the completion of steel smelting, casting chemical composition of the medium-term. To make a good representative, or on behalf of the furnace or tank, the average compositions of the standard method of sampling requirement will cast molten steel in the mold like a small tablet, on which plane to take or drill cuttings samples, according to the required standards method (GB/T223) analysis, the results must meet the standards of the chemical composition range, is also the basis for customer acceptance.
② finished components
Verification of product ingredients known components, is required from the finished steel on the way (GB/T222) drill or dig sampling chips, according to the provisions of the standard method (GB/T223) to analyze the chemical composition obtained. Steel in the mold and after the plastic deformation in steel alloying elements due to the uneven distribution (segregation), thus allowing for the standard composition range of components and finished products (melting components) there are deviations between, the deviation should be consistent with the provisions of GB/T222 .
The main constituents of finished steel products for use department or the quality inspection department of quality inspection of steel used, production companies generally do not do product analysis (except as required by the user), but should ensure that finished products meet the standard requirements analysis.
③ arbitration of
As both the results of laboratory analysis of the same samples were significantly different from and beyond the two laboratories to allow analysis of the error, or the production and use of corporate sector, demand-side and supply-side on the same samples or with a group of Analysis of finished steel, when there is disagreement , by third-party authority with extensive experience in analysis units (such as the China Iron and Steel Research Institute, or the inspection department with the inspection qualifications) for further analysis, that is commonly known that the arbitration analysis. Arbitration shall be final determination based on the results. (4) The term mechanical properties
Mechanical properties of steel is to ensure that end-use properties of steel (mechanical properties) of the key indicators, it depends on the steel chemical composition and heat treatment. In the steel standards, based on different usage requirements to the tensile properties (tensile strength, yield strength or yield point, elongation) and hardness, toughness index, as well as users demand high and low temperature capabilities.
① tensile strength (σb)
Sample in the tensile process, the pull off the most vigorously when exposed (Fb), out to sample the original cross-sectional area (So) from the stress (σ), called the tensile strength (σb), units N/mm2 (MPa). It said that under the action of metallic materials to resist the pull of the maximum damage. The formula is: Type in: Fb-sample pull off the most vigorously when exposed, N (Newton);So-sample the original cross-sectional area, mm2.
② yield point (σs)
Yielding of metal materials with the specimen during the tensile force does not increase (remain constant) could continue to stretch the stress, called yield point. If the drop occurs when the force should distinguish between the upper and lower yield point. Yield point of the unit N/mm2 (MPa). The yield point (σsu): sample occurred before the first drop power yield and maximum stress; Lower yield point (σsl): When excluding the initial transient effect, the yield stage of the minimum stress. Yield point is calculated as: The formula: Fs-yield process for tensile strength (constant), N (Newton); So-sample the original cross-sectional area, mm2.
③ Elongation (σ)
In tensile testing, fractured the increase in its gauge length and the percentage of the original gauge length, referred to as elongation. With σ that as%. The formula is: ; The formula: L1-fractured in the gauge length, mm; L0-sample the original gauge length, mm.
④ section shrinkage (ψ)
In the tensile test, the fractured cross-sectional area of its necking Department to reduce the maximum amount of the percentage of the original cross-sectional area, known as section shrinkage. To ψ that as%. Calculated as follows: Type in: S0-sample the original cross-sectional area, mm2; S1-fractured necking Department at least cross-sectional area, mm2.
⑤ hardness index
The hard metal object against the capacity of the surface indentation, known as hardness. According to different test methods and scope of application, can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, Shore hardness, microhardness and high temperature hardness. Commonly used for the pipe are Brinell, Rockwell, Vickers hardness of three.
A, Brinell hardness (HB)
With a certain diameter carbide ball or a ball, to provide the test force (F) onto the pattern surface, removable by the provisions of the time after the test force, indentation diameter measurement surface of the sample (L). Brinell hardness test force is obtained by dividing the indentation of spherical surface area business. With HBS (ball) that, in units of N/mm2 (MPa).
The formula is:
The formula: F-pressed into the metal surface of the sample test force, N;
D-test with a ball diameter, mm;
d-indentation average diameter, mm.
More accurate and reliable determination of Brinell hardness, but in general HBS is only applicable to 450N/mm2 (MPa) below the metal material, the harder the steel or thin sheet does not apply. Standards in the steel, Brinell hardness most widely used and often indentation diameter d to represent the hardness of the material, both intuitive, and convenient.
For example: 120HBS10/1000130: 10mm diameter, said steel ball in 1000Kgf (9.807KN) test force, to maintain the 30s (seconds) measured Brinell hardness value of 120N / mm2 (MPa).
B, Rockwell hardness (HK)
Rockwell hardness test Brinell hardness test with the same, all indentation test method. The difference is that it is a measure of the depth of indentation. That is, in the early Yong Test Force (Fo) and total test force (F) under the sequence, the pressure head (gold steel cone or ball) onto the surface of the sample, by provisions of the time, exclude the main test force, indentation depth by measuring the residual increment (e) calculating the hardness value. Its value is unknown numbers, to sign HR said that there used to scale A, B, C, D, E, F, G, H, K, etc. 9 scale. One commonly used scale in steel hardness tests usually A, B, C, or HRA, HRB, HRC.
Hardness values calculated with the following:
When using A and C benchmark test, HR = 100-e
When the ruler with the B test, HR = 130-e
Type in e-residual indentation depth increment, the even lines to provide units of 0.002mm, ie the axial displacement when the pressure head of a unit (0.002mm), that is equivalent to a Rockwell hardness number of changes. e value the greater the lower the hardness of the metal, otherwise the higher hardness.
Application of the three scale as follows:
HRA (diamond cone indenter) 20-88
HRC (diamond cone indenter) 20-70
HRB (1.588mm diameter steel ball indenter) 20-100
Rockwell hardness test is the wide application of the method, in which the use of HRC after the steel standard Brinell hardness HB. Rockwell applied to the determination by the extremely soft to extremely hard metal material, it is not up for Bridgman than Brandt's method is simple and can dial directly from the hardness machine read the hardness value. However, because of its small indentation, so as Brinell hardness method is accurate.
C, Vickers hardness (HV)
Vickers indentation hardness test is also a test method, is a relative angle between surfaces 1360 of a rectangular pyramidal diamond indenter to the selected test force (F) onto the test surface, removable by the provisions of the time trial force, measured indentation diagonal length of the two. Vickers hardness test force is obtained by dividing the indentation surface operators, the formula is: Type in: HV-Vickers hardness of symbols, N/mm2 (MPa); F-test force, N; d-indentation arithmetic mean of the two diagonal, mm. Vickers hardness test force F applied to 5 (49.03), 10 (98.07), 20 (196.1), 30 (294.2), 50 (490.3), 100 (980.7) Kgf (N) and other six can be measured hardness the range of 5 ~ 1000HV. Representation example: 640HV30/20 that with 30Hgf (294.2N) test force 20S (seconds) measured Vickers hardness values 640N/mm2 (MPa).
Vickers hardness method can be used to determine the thin layer of metal material and surface hardness. It has a Brinell, Rockwell method of the main advantages to overcome their fundamental flaws, as Rockwell method is simple. Vickers method rarely used in the steel standard. ⑥ toughness index
Toughness of metal to come to reflect the impact of external load Oh, resistance, usually by the impact toughness (ak) and impact energy (Ak) said its units were J/cm2 and J (J).
Toughness or impact energy test (the "impact test"), divided into different test temperature due to ambient temperature, low temperature and high temperature impact test of three; if the gap according to the shape of the sample can be divided into "V"-shaped notch and the "U" notch impact test two.
Impact test: a certain size and shape (10 × 10 × 55mm) of the sample (the middle of the length of the direction of a "U" type or "V" notch, notch depth of 2mm) in the test machine under the provisions of the devastating impact load from notch fracture experiment.
A, the impact absorbed energy Akv (u) - a certain size and shape of the metal pattern, broken under the impact load when the power absorbed. Units of joules (J) or Kgf. M.
B, impact toughness akv (u) - impact energy divided by the cross sectional area of the sample gap in the bottom of the income of the business. Units of J / cm 2 (J/cm2) or kilograms force. M / cm 2 (Kgf. M/cm2). The formula is: Type in: Akv (u) - absorbed by the sample when the power break, Kgf. M (J); S - sample gap in the bottom of the cross-sectional area, cm2.
Room temperature impact test temperature of 20 ± 50C; low-temperature impact test temperature range of <15 ~-1920C; temperature impact test temperature range of 35 ~ 10000C.
Low-temperature impact test normally used for cooling medium non-toxic, safe, non-corrosive metal and is not frozen at the test temperature of liquid or gas. Such as ethanol (alcohol), solid carbon dioxide (dry ice) or liquid nitrogen spray gas (nitrogen) and so on.
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