Fluid seamless steel pipe&tube
FluidSeamless Steel Tubes have hollow sections, which are used as pipelinesfor conveying fluids, such as pipelines for the transportation of oil,natural gas, gas, water and certain solid materials. Steeland round steel and other solid steel compared to the same bendingstrength, the weight is light, is an economic section of steel, widelyused in the manufacture of structural parts and mechanical parts, suchas oil drill pipe, car drive shaft, bicycle Frame construction and steel scaffolds used in the construction ofsteel ring parts, can improve the utilization of materials, simplify themanufacturing process, saving materials and processing time, has beenwidely used to manufacture steel.--(Seamless steel tube)
Components and mechanical parts
Standing resource material
10 #, 20 #, 35 #, 45 #, 16Mn
Themechanical properties of steel are important indicators to ensure theultimate use of steel (mechanical properties), which depends on thechemical composition of steel and heat treatment system. In the steel pipe standard, according to the different requirements,the tensile properties (tensile strength, yield strength or yield point,elongation) and hardness, toughness indicators, as well as the userrequirements of high and low temperature performance.
① Tensile strength (σb)
Themaximum force (Fb) of the specimen in the drawing process, divided bythe original cross-sectional area (So) of the specimen, is called thetensile strength (σb) in units of N / mm2 (MPa). It represents the maximum capacity of metal materials to resist damage under tension.
② yield point (σs)
Withthe yield phenomenon of the metal material, the sample in the tensileprocess does not increase (to maintain a constant) can continue tostretch the stress, called the yield point. If the force falls, it should distinguish between the upper and lower yield points. The unit of yield point is N / mm2 (MPa).
(Σs): the maximum stress before the first drop of the specimen; thelower yield point (σsl): the minimum stress in the yield phase when theinitial transient effect is not counted.
The yield point is calculated as:
Where: Fs - the tensile strength of the sample during the test(constant), N (Newton) So - the original sample cross-sectional area,mm2.
③ elongation after breaking (σ)
Inthe tensile test, the length of the gauge length after the specimen ispulled off is the percentage of the length of the original gauge length,called the elongation. Expressed in σ, in%. The formula is: σ = (Lh-Lo) / L0 * 100%
Where: Lh - the length of the specimen after the withdrawal from thegauge length, mm; L0 - the original sample length length, mm.
④ section shrinkage (ψ)
Inthe tensile test, the maximum reduction in the cross-sectional area atthe reduced diameter and the percentage of the original cross-sectionalarea after the specimen is broken is called the section shrinkage. Expressed in ψ, in%. Calculated as follows:
Where: S0 - the original cross-sectional area of the sample, mm2; S1- the minimum cross-sectional area of the specimen after the break,mm2.
⑤ hardness indicators
The ability of a metal material to resist the surface of a hard object is called hardness. Accordingto the test method and the scope of application, the hardness can bedivided into Brinell hardness, Rockwell hardness, Vickers hardness,Shore hardness, micro hardness and high temperature hardness. For the pipe commonly used are Brinell, Rockwell, Vickers hardness of three.
A, Brinell hardness (HB)
(F)is pressed against the pattern surface with a predetermined test force(F) with a certain diameter ball or carbide ball. After the specifiedholding time, the test force is removed and the indentation diameter (L)of the sample surface is measured. Brinell hardness is calculated by dividing the test force by the indentation spherical surface area. It is expressed in HBS (steel ball) in units of N / mm2 (MPa).
The formula is:
Where: F - into the metal sample surface test force, N; D - test ball diameter, mm; d - indentation average diameter, mm.
Determinationof Brinell hardness is more accurate and reliable, but the general HBSonly applies to 450N / mm2 (MPa) the following metal materials, for hardsteel or thin plate is not applicable. In the steel pipe standard, Brinell hardness is the most widely used,often with indentation diameter d to represent the hardness of thematerial, both intuitive and convenient.
Example: 120HBS10 / 1000/30: indicates a Brinell hardness value of 120N / mm2 (MPa) measured for 30 seconds (seconds) under a test force of1000 Kgf (9.807 KN) with a diameter of 10 mm.
Seamless steel pipe is widely used. Generaluse of seamless steel pipe from the ordinary carbon structural steel,low alloy structural steel or alloy structural steel rolling, thelargest output, mainly used for conveying fluid pipe or structuralparts. .2,according to the use of different sub-three supply: a, according tochemical composition and mechanical properties of supply; b, accordingto the mechanical properties of supply; c, according to the hydraulictest supply. According to a, b class supply of steel pipe, such as for the use of liquid pressure, but also for water pressure test. 3, the special purpose of the seamless pipe with a seamless pipe,chemical power, geological seamless steel pipe and seamless use of oiland so on.
Refers to the final plastic deformation of the delivery product or the state of the final heat treatment. Itis said that the heat treatment is not heat-treated or it is calledhot-rolled or cold-drawn (rolled) state or manufacturing state. The heattreatment is heat-treated or heat-treated, normalized, status. When ordering, the delivery status should be indicated in the contract. Weight Delivery Status:
Actual weight - when delivered, the weight of the product is delivered by weight (weighing)
Theoretical weight - When delivered, the weight of the product is calculated from the nominal size of the steel.
① hot-rolled seamless steel pipe main production process (△ main inspection process):
Tube blank preparation and inspection △ → tube heating → perforation →rolling → steel pipe reheating → set (minus) diameter → heat treatment △→ finished pipe straightening → finishing → inspection △ (lossless,physical and chemical, Taiwan inspection) → storage
② cold-rolled (pull) seamless steel pipe Main production process:
Ingredients → Pickling Lubrication → Cold Rolling → Heat Treatment → Straightening → Finishing → Inspection
Generalseamless steel pipe production process can be divided into cold drawingand hot rolling two, cold-rolled seamless steel pipe production processis generally more complicated than hot-rolled, tube first to bethree-roll rolling, after extrusion to be carried out Sizingtest, if the surface is not responding to the crack after the tube togo through the cutting machine for cutting, cutting into a length ofabout one meter of blank. Andthen enter the annealing process, the use of acidic acid for acidpickling, pickling should pay attention to whether the surface of alarge number of foaming produce, if there is a large number ofblistering that the quality of steel pipe can not meet the correspondingstandards. Theappearance of cold-rolled seamless steel pipe is shorter thanhot-rolled seamless steel pipe, cold-rolled seamless steel pipe wallthickness is generally smaller than the hot-rolled seamless steel pipe,but the surface looks thicker than thick-walled seamless steel pipe, thesurface is not too More rough, caliber no too much burr.
Hot-rolled seamless steel pipe delivery status is generally hot-rolled state after heat treatment for delivery. Hot-rolledseamless steel pipe after the quality inspection to go through therigorous manual selection of workers, after the quality inspection tothe surface of the oil, and then followed by a number of cold drawingexperiments, hot rolling after the perforation of the experiment , If the perforation is too large to be straightening correction. In the straightening and then sent by the transmission device to theflaw detector for testing, and finally labeled, the specificationsarranged after the placement into the warehouse.
Roundpipe → heating → perforation → three roll skew rolling, continuousrolling or extrusion → off pipe → sizing (or reducing diameter) →cooling → straightening → water pressure test (or flaw detection) → mark→ storage seamless steel pipe Is made of steel ingot or solid tube through the perforated tube, and then by hot rolling, cold or cold made. The specifications of the seamless steel pipe are indicated by the outer diameter * wall thickness mm.
Hot-rolledseamless pipe diameter is generally greater than 32mm, wall thicknessof 2.5-200mm, cold-rolled seamless steel pipe diameter to 6mm, wallthickness to 0.25mm, thin-walled tube diameter to 5mm wall thickness ofless than 0.25mm, cold Rolling ratio is higher than that of hot rolling.
Generaluse of seamless steel pipe is 10,20,30,35,45 and other high-qualitycarbon steel 16Mn, 5MnV and other low-alloy structural steel or 40Cr,30CrMnSi, 45Mn2, 40MnB and other synthetic steel made of hot-rolled orcold-rolled. 10,20 and other low-carbon steel seamless pipe is mainly used for fluid pipeline. 45,40Cr and other carbon steel made of seamless pipe used to manufacture mechanical parts, such as cars, tractors force parts. General use of seamless steel pipe to ensure strength and flattening test. The hot-rolled steel pipe is delivered in a hot-rolled state or aheat-treated state; the cold-rolled steel is delivered in a heat-treatedstate.
Hotrolling, as the name suggests, the rolling of the high temperature, sothe deformation resistance is small, you can achieve a large amount ofdeformation. Rollingsteel as an example, the general continuous casting slab thickness ofabout 230mm, and after rough rolling and finishing, the final thicknessof 1 ~ 20mm. Atthe same time, due to the width of the steel plate is small, the sizeof the precision requirements are relatively low, not prone toplate-shaped problem to dominate the convex. Forthe organization requirements, generally through the control of rollingcontrol to achieve, that is, control the rolling of the rollingtemperature, finishing temperature. Round tube → heating → perforation →start → annealing → pickling → oil (copper) → Multi-passcold drawing (cold rolling) → billet → heat treatment → straightening →water pressure test (flaw detection) → mark → storage