40cr steel pipe characteristics and the purpose

 

Mechanical Properties

 

Sample blank size (mm): 25

 

Heat treatment:

 

First quenching temperature (° C): 850; coolant: oil

 

Second quenching temperature (° C): -

 

Tempering heating temperature (℃): 520; coolant: water, oil

 

40cr pipe roundwood

 

Tensile strength (σb / MPa): ≧ 980

 

Yield point (σs / MPa): ≧ 785

 

Elongation rate (δ5 /%): ≧ 9

 

Section shrinkage (ψ /%): ≧ 45

 

Impact absorbed energy (Aku2 / J): ≧ 47

 

Brinell hardness (HBS100/3000) (annealing or tempering state): ≦ 207

 

 

 

40cr pipe quenched and tempered hardness40cr pipe hardness after quenching and tempering is probably HRC32-36, that is probably HB330-380.

 

40cr pipe - 830-860C oil quenching -> 55HRC

 

150C tempered - 55HRC

 

200C tempered - 53HRC

 

300C tempered - 51HRC

 

400C tempered - 43HRC

 

500C tempered - 34HRC

 

550C tempered - 32HRC

 

600C tempered - 28HRC

 

650C tempered - 24HRC

 

Of 40cr pipe characteristics and uses

 

Characteristic

 

In carbon the modulation steel pipe, cold heading die steel pipe. The steel pipe affordable, easy processing obtained by appropriate heat treatment after a certain toughness, ductility and wear resistance.Normalizing promote tissue ball, to improve hardness less than 160HBS rough cutting performance.At a temperature of 550 ~ 570 ℃ tempering, the steel pipe has the best mechanical properties. The hardenability of the steel pipe higher than 45 steel pipe, suitable for surface hardening treatment of the high-frequency hardening, flame quenching.

 

Use

 

Quenched and tempered after this steel pipe used in the manufacture of mechanical parts withstand medium-load and medium-speed work, such as automotive steering knuckles, rear axle, and on the machine shaft, worm, spline shaft, tailstock etc.; Quenched tempering used in the manufacture of parts to withstand high loads, shock and medium speed work, such as gears, spindle, oil pump rotor, slider, collars; withstand heavy loads after quenching and tempering used in the manufacture of low-impact and has the abrasion resistance, the thickness of the cross section entities in 25mm below the parts, such as the worm and spindle shaft, collar, etc.; for manufacturing a high surface hardness and abrasion resistance after quenching and tempering and the high-frequency surface hardening no great impact on the parts, such as gears, sleeves, shaft, spindle, crank spindle, pins, connecting rods, screws, nuts, intake valve. In addition, this steel pipe is also suitable for producing the carbonitriding process, a variety of transmission parts, such as the relatively large diameter and low temperature toughness, good gear and the shaft.

 

[Supplier status and hardness]

 

Annealed hardness ≤ 207HBS.

 

40cr pipe shaft parts

 

Shaft parts is one of the frequently encountered in typical machine parts. It is mainly used to support the transmission components, torque transmission and load bearing. The shaft parts is part of the rotating body, its length is greater than the diameter, generally by the outer cylindrical surface of the concentric shaft, conical surface, the inner hole and the thread and the corresponding end surface. Depending on the structural shape, can be divided into the optical axis, stepped shaft, hollow shaft and crank shaft parts.

 

Axis aspect ratio of less than 5 is referred to as the minor axis, greater than 20 are referred to as the elongate shaft, most of the shaft in between.

 

Shaft with a bearing support, referred to the bearing with the shaft section journaled. Journal shaft assembly normally require a higher benchmark their accuracy and surface quality, the technical requirements are generally formulated according to the axis of the main function and working conditions, usually the following:

 

(A) from the dimensional accuracy of the supporting role of the journal in order to determine the position of the axis, usually its high dimensional accuracy requirements (IT5 ~ IT7).Journal of the assembly of transmission parts dimensional accuracy is generally lower requirement (IT6 ~ IT9).

 

(B) the geometry of the accuracy of the accuracy of the geometry of the shaft parts mainly refers to the journal, outer cone morse taper hole such as roundness, cylindricity, and generally its tolerance should be limited to the dimensional tolerance range. High precision internal and external circular surface, should be marked on the drawing of its allowable deviation.

 

(C) the mutual position accuracy of the positional accuracy requirements of the shaft parts of the main by the shaft in the machinery in position and function of the decision. Should normally ensure that the assembly Transmission Parts journal bearing journal concentricity requirements, otherwise it will affect transmission parts (gear) transmission accuracy, and generate noise.Ordinary accuracy of the shaft, with the shaft section of the radial direction of the bearing journal beating generally 0.01 ~ 0.03mm, high precision axis (such as the spindle) is usually 0.001 ~ 0.005mm.

 

(Iv) surface roughness typically cooperates with the transmission member the shaft diameter of the surface roughness of Ra2.5 ~ 0.63μm, surface roughness of cooperating with bearings supporting the shaft diameter for Ra0.63 to 0.16μm.

 

Rough and materials

 

(A) shaft parts the rough shaft parts according to the requirements, production type, equipment condition and structure, the selection of bars, forgings rough form. Little difference between the axis for the outer diameter, generally bar; outer diameter difference between the large stepped shaft or shaft, often used in forging, so that both saving materials and reducing the workload of the machining, but also improve the mechanical properties.

 

Depending on the production scale, rough forging free and die forgings two. Small and medium batch free forging, a large number of mass-produced using forging.

 

(B) the material of the shaft parts shaft parts requires selection of different materials and different heat treatment specifications (such as quenching and tempering, normalizing, quenching, etc.), in order to obtain a certain strength, toughness, and depending on the working conditions and the use of wear resistance.

 

40cr pipe shaft parts used materials, it is cheap (or normalizing) after quenching, better cutting performance can be obtained, but also to obtain higher mechanical properties such as strength and toughness, after quenching, surface hardness up to 45 ~ 52HRC.

 

40cr pipe alloy structural steel pipe suitable for medium accuracy and high speed shaft parts, quenched and the quenching of this type of steel pipe, has good mechanical properties.

 

GCr15 bearing steel pipe and spring steel pipe 65Mn, after quenched and the high-frequency quenching, surface hardness up to 50 ~ 58HRC, and have higher fatigue resistance and good wear resistance, higher precision of the shaft can be manufactured.

 

Precision machine tool spindle (eg grinding wheel axis jig borer spindle) optional 38CrMoAIA nitrided steel pipe. This steel pipe after quenching and surface nitriding, can not only obtain a high surface hardness, and can keep a relatively soft core portion, and therefore good resistance to impact toughness. And carburized steel pipe, heat treatment deformation is small, higher hardness characteristics.

 

The 40cr pipe widely used in machinery manufacturing, and mechanical properties of this steel pipe is good. But this is a medium carbon steel pipe, quenched performance is not good, 40cr pipe hardened to HRC42 to 46. So if necessary, surface hardness, and want to play 40cr pipe superior mechanical properties, 40cr pipe surface carburizing quenching often, so you can get the desired surface hardness.

 

40cr pipe elastic modulus

 

40cr pipe modulus of elasticity: elastic modulus E (20 ℃) / MPa 200000 ~ 211700, shear modulus G (20 ℃) 80800

 

Heat treatment process

 

Quenching process

 

40cr pipe quenching 850 ℃, oil cooling; tempering 520 ° C, water, oil. 40cr pipe surface quenching hardness HRC52-60, flame hardening can reach HRC48-55.

 

Nitriding process

 

40cr pipe belong to the nitride steel pipe, which contains elements conducive to nitride. 40cr pipe after the nitriding treatment to obtain a higher surface hardness, the hardness of the nitriding treatment in the 40cr pipe quenched after highest attainable HRA72 ~ 78, i.e. HRC43 to 55.

 

Nitride workpiece process route: forging - annealing - roughing - quenching and tempering - finishing - in addition to stress - kibble - nitride - fine grinding or abrasive. Nitride layer is thin and brittle, thus requiring the heart tissue have a higher intensity, so the first transfer of heat treatment, sorbite to improve the Heart Ministry mechanical performance and the quality of the nitrided layer. The soft nitriding reactive nitrogen used gas nitriding.

 

Welding

 

Before 40cr pipe welding preheat, to prevent matrix heat, causing the weld internal quench quench cracking. Plus the best in the quenched and tempered after welding again normalizing.

 

40cr pipe welding:

 

The crystallization easy segregation, is more sensitive to the crystalline crack (a thermal cracking), welding easy in craters and weld recessed portion cracking. Higher carbon content, rapid cooling is easy to be very sensitive to cold cracking of hardened tissue (martensite).Overheated zone in the cooling rate is larger, it is easy to form hard and brittle carbon martensite so overheated zone embrittlement.

 

Welding process points:

 

1, the general state of the annealing (normalizing) to be welded.

 

2, the welding method unrestricted

 

3, with a larger line energy, an appropriate increase in the preheat temperature, general preheat temperature and inter-layer temperature can be controlled between 250 ~ 300 ℃.

 

4, welding materials should ensure that the deposited metal composition substantially identical with the parent material, such as the J107-Cr

 

5 should timely transfer of heat treatment after welding. If timely quenching and tempering treatment is difficult, can be carried out intermediate annealing or insulation higher than the preheated temperature for a period of time, to exclude the diffusible hydrogen and softened tissue. Products of more complex structure, weld can be finished welding after a certain number of welds, the primary intermediate annealing.

 

Delivery Status

 

40cr pipe delivery status to heat treatment (normalizing, annealing or tempering) or without heat treatment delivery, the delivery status should be specified in the contract.

 

Representation

 

① steel pipe at the beginning of the two numbers indicate the carbon content of the steel pipe, said the average carbon content of the very few, such as 40cr pipe, 25Cr2MoVA alloy pipe ② steel pipe major alloying elements, in addition to individual micro-alloying elements, generally a few percent said. When the average alloy content of <1.5%, steel pipe generally marked element symbols, rather than marked content prone to cause confusion, but in exceptional circumstances, can also be marked with the number "1" in the element symbols, such as steel pipe, No. the the "12CrMoV" and "12Cr1MoV", the former of chromium content of 0.4-0.6%, the latter is 0.9-1.2%, and the remaining components are all the same. When the average content of alloying elements ≥ 1.5% ≥ 2.5% ≥ 3.5% ... behind the element symbols should be marked content, corresponding to 2,3,4 ... and so on. For example, 18Cr2Ni4WA.

 

③ steel pipe vanadium V, titanium Ti, AL aluminum, boron B, and rare earth RE, alloying elements, are micro-alloying elements, although the content is very low, should remain in the steel pipe marked. E.g. 20MnVB steel pipe. Vanadium 0.07-0.12% and 0.001-0.005% boron.

 

④ High quality steel pipe in the steel pipe and finally add the "A", to distinguish it from the general high quality steel pipe.

 

 

1 40CR Seamless pipe Application

Low and middle pressure fluid transportation pipeline

Casing Tube

Boiler Pipe

Petroleunm and natural gas industry

Chemistry industry

Electric industry

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