What is the allowable stress value of 40Cr material?

1) Characteristics Medium carbon modulated steel, cold heading die steel. The steel is moderate, easy to process, and can obtain certain toughness, plasticity and wear resistance after proper heat treatment. Normalizing can promote spheroidization of the tissue and improve the cutting performance of blanks with a hardness of less than 160HBS.

Tempered at a temperature of 550 570, the steel has the best comprehensive mechanical properties. The hardenability of the steel is higher than that of 45 steel, and it is suitable for high-frequency quenching, flame quenching and other surface hardening treatments.

2) Supply condition and hardness annealed state, hardness 207HBS.

3) Standard GB T 3077-1999 Chemical Composition of Steel (Mass Fraction, %)c.

4) Refer to the corresponding steel grade China's GB standard steel grade is 40Cr, German DIN standard material number German DIN standard steel 41Cr4 42GR4, British EN standard steel 18, British BS standard steel 41Cr4, French AFNOR standard steel 42C4, French NF standard steel 38Cr4 41Cr4, Italy UNI standard steel 41Cr4, Belgian NBN standard steel 42Cr4, Sweden SS standard steel 2245, AISI SAE ASTM standard steel grade 5140, Japan JIS standard steel grade SCR440(H) SCR440, American AISI SAE ASTM standard steel grade 5140, ISO standard steel grade 41cr4.

5) Critical point temperature (approximate) acm=780

6) Normalizing specification temperature 850 870, hardness 179 229hbs.

7) Cold-pressed blank softening treatment specification temperature 740 760, holding time 4 6h, and then 5 10 h cooling rate, cooling to 600, out of the furnace air cooling.

The hardness is 217HBS before treatment and 163HBS after softening.

8) Pig iron filings protection swing tempering specification (670 10) 2h, heating with furnace, (710 10) 2h, cooling with furnace, (670 10) 2h, heating with furnace, (710 10) 2h, then cooling with furnace, (670 10) 2h, heating with furnace, (710 10) 2h, cooling with furnace, a total of 3 cycles, then cooling to 550, air cooling out of furnace. After treatment, the hardness is 153HBS.

9) Quenching and tempering treatment specification quenching temperature 850 10, oil cooling; Tempering temperature 520 10, water, oil air cooling.

Bolt Strength Calculation 10-7 Bolt Material and Allowable Stress Measures to improve bolt strength.

The commonly used materials for bolts are Q215, Q and 45 steel, and alloy steels with high mechanical properties such as 15Cr, 30Cr Mnsi and 40Cr can be used for important and special purposes. It should be noted that the materials are the same, but the manufacturing process is different, which can make the mechanical properties of bolts and nuts quite different.

Therefore, the national standard divides threaded fasteners into 10 grades according to mechanical properties. In use, it is best to choose the appropriate performance level according to the requirements (the performance level is one of the indicators for purchasing fasteners), without having to delve into what material it is. The performance levels of bolts and nuts are shown in Table 10-6

Table 10-6 Performance of bolts and nuts.

Bolt performance class.

Nut Performance Grade 4 5 6 8 9 10 12Note: 1In the grade code of the bolt, the number before the dot is 100 and the digit after the dot is 10 ( ).

2.The performance grade code number of the nut indicates 100.

Table 10-7 Allowable stresses of bolted connections.

The load of the tight bolt connection is allowable force.

Axial load, lateral load ]= s

When controlling the preload, s=; When the preload is not controlled, S checks Table 10-8.

Bolts for reaming holes.

Subjected to transverse loads.

Static load

The connected parts are steel).

2 (Cast iron).

Variable load

Reduce the value of static load by 20% or 30%.

Table 10-8 Safety factor s of tightened bolted connection s (when preload is not controlled), material static load, variable load.

m6 16 m16 30 m6 16 m16 30 carbon steel.

Alloy steel 4 3

The allowable stress is also the tensile strength. HB241--286 is only about 28 when converted to HRC. The tensile strength is 990mpThe stress is undetectable, and it is not known if it does not crack, and it is scrapped after it is known.

The allowable stress of 40cr steel is (safety factor n= : allowable end face compressive stress =; Allowable shear stress=; Allowable compressive bending stress = the hardness after quenching and tempering is about between HRC32-36, that is to say, about HB301-340.

40CR is alloy steel, which has good comprehensive mechanical properties after quenching and tempering, and is used to manufacture medium-speed and medium-load parts, such as machine tool gears, shafts, worms, spline shafts, etc., which can replace 40mnb, 45mnb, 35simn, 42simn, 40mnvb and so on.

The ultimate stress of the component failure.

Components made of brittle materials, under the action of tensile force, when the deformation is very small, will suddenly break, and the stress when the brittle material breaks is the strength limit b; The component made of plastic material has plastic deformation before it is pulled, and without considering the mechanical design method of plastic deformation, considering that the component can not maintain the original shape and size, it is considered that it can no longer work normally, and the stress when the plastic material reaches yield is the yield limit s. The strength limit of brittle materials b, the yield limit of plastic materials s is called the ultimate stress of component failure.

Mechanical properties.

Specimen blank size (mm): 25

Heat treatment: the first quenching heating temperature ( ) 850; Coolant: Oil second quenching heating temperature ( ).

tempering heating temperature ( ) 520;

Tensile strength (b mpa): 810 (when the actual hardness is 25hrc) yield point (s mpa): 785

Elongation after fracture (δ5 %): 9

Section shrinkage (%): 45

Work of impact absorption (aku2 j): 47

Brinell hardness (100 3000HBW) (annealed or tempered at high temperature): 207

Tensile 980

Yield 785 surface quenching hardness 48 55HRC

See GB T 3077

Dear, hello, I am glad to answer for you, what is the yield strength of 40cr in the state of the original Zheng type clear material A40cr tensile strength b yield strength s belongs to the national standard alloy structural steel, the implementation standard: GB T steel is a medium carbon low alloy steel, the tensile strength of the chartered sail after quenching and tempering treatment is 1000MPa, and the yield strength is 800MPa (stress corresponding to residual elongation). The structure before the quenching and tempering of 40cr steel is tempered sostenite, which has a good strength and toughness fit (with high strength, toughness, plasticity, fatigue limit and fracture toughness, and a low brittle-tough transition temperature), which is suitable for making shaft parts with complex stress and high performance requirements.

The allowable stress of 40cr steel has (safety factor n= :

1.Allowable end face bearing stress=;

2.Allowable shear stress=;

3.Allowable compressive bending stress = .

Allowable stress: The maximum value of stress that a part or component is allowed to withstand in a mechanical design or engineering structural design. In order to determine whether the working stress of a part or component is too high or too low after loading, it is necessary to determine a measurement standard in advance, which is the allowable stress.

When the working spring rent stress in the part or component does not exceed the allowable stress, the part or component is safe in operation, otherwise it is unsafe. Allowable stress is the basic data in mechanical design and engineering structural design. In practical application, the allowable stress value is generally specified by the national engineering department according to the principle of safety and economy, according to the strength of the material, the spring load, the environmental conditions, the processing quality, the calculation accuracy and the importance of the parts or components.

The allowable stress is equal to the failure stress of the appropriately corrected material after considering various influencing factors divided by the safety factor. Plastic materials (most structural steels and aluminum alloys) are based on the yield limit and divided by the safety factor to obtain the allowable stress, i.e., [ ]s n(n=; Brittle materials (cast iron and high-strength steel) are divided by the strength limit to obtain the allowable stress, i.e., [ ]b n(n=2 5). (n is the safety factor).

Kiss! Hello, it's a pleasure to answer your <> for the wheel

The yield strength of pro-40cr in the raw material state is 785 n mm2 The yield strength is the yield limit of the metal material when the yield phenomenon occurs, that is, the stress that resists trace plastic deformation. For metal materials without obvious yield phenomenon, the stress value of residual deformation is used as its yield limit, which is called the conditional yield limit or yield strength. An external force greater than the yield strength will cause the part to fail permanently and cannot be recovered.

For example, the yield limit of mild steel is 207MPa, when the external force greater than this limit acts, the parts will produce permanent deformation, less than this, the parts will return to their original appearance. Hope mine can help you <>

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