The tensile strength
The tensile strengthRm(also called the tear strength) was to evaluate the strength of material property values.The tensile strength is the biggest mechanical tensile stress of specimen can be loaded.If more than the tensile strength, the material failure: force absorption decreases, until finally the material sample.Before, however, actual tensile strength value is reached, the material would undergo plastic deformation (residual).
To calculateDifferent materialHardening of the gradeOther property valuesThe sampleTesting machineTensile testThe yield point
What is the tensile strength?
The tensile strengthRmThrough the determination of tensile test (for example, according toThe ISO 6892Series of standards orThe ISO 527Series standard, the former is applicable to metal material, which is suitable for plastic and composite materials).
According to the test start at the maximum tensile force FmSample cross section area is calculated and the tensile strength:
The tensile strength RmF = maximum tensile forcem/ sample cross sectional area S0
The tensile strengthIn MPa (MPa) or N/mm squared.
The stress-strain diagram (also known as the stress-strain curve), drawing in the tensile test specimen tensile stress varies with its corresponding length variation.
The curve can be used to determine the different characteristics of the material under test values, for example, the elastic properties and tensile strength.In the stress-strain diagram, the tensile strength is increased tensile stress in the pulling test again after the biggest stress value.
The tensile strength of the material hardening are at different levels
To have clearThe yield pointMetal materials, defined as the maximum tensile forceThe yield strengthAfter reached the most strongly.For weak strain hardening material, after more than the yield strength of the maximum tensile force may also be lower than the yield point, so in this case, the tensile strength is lower than the yield strength value.
The right of the stress-strain curve shows a high degree of strain hardening (1), after the yield point has lower degree of strain hardening curve (2).
On the other hand, with the yield point and subsequent stress of plastic,The tensile strengthCorresponding to the yield stress of the point.
To evaluate the other feature values of strength
In order to evaluate the intensity of performance, in addition to the measurementThe tensile strengthOutside, still should determine upper and lower yield point as well as the fracture strength and tear strength.
The yield pointIs usually defined as the transition from elastic deformation to plastic deformation of the stress.It is the elastic limit, the upper and lower yield strength (tensile test), compression yield strength (Compression test), bending yield strength (Bending test) or reverse yield strength (Torsion testGeneric term).
On the other hand,Plastic elongation strengthRefers to the already contains a certain residual or total elongation stress.They with metal materials used in marking continuous transition from elastic to plastic range.
The termThe yield point(also known as the yield stress) is often used in rheology, describe stress value of the flow of material (especially for plastic).The characteristics of the flow is when beyond the yield point, material or irreversible plastic deformation occurs.
For many materials, the maximum test force Fm, the force and the nominal tensile stress decreases with the increase of elongation, until the specimen fracture or tear.Related to the initial cross-sectional area of fracture force, also known asFracture strength and tear strength.It is an important parameter, especially for plastic.For brittle metal material, toughness plastic elastomer and no yield point, tear strength is usually equal to the tensile strength.
Metal material tensile strength sample values
| The name of the material | Material number | The old name | Rm | Rp0.2 |
|---|---|---|---|---|
| S235JR | 1.0037 | St37-2 | 360 | 235 |
| S275JR | 1.0044 | St44-2 | 430 | 275 |
| S355J2G3 | 1.0570 | St52-3 n | 510 | 355 |
| C22E | 1.1151 | Ck22 | 500 | 340 |
| 28 mn6 | 1.1170 | 28 mn6 | 800 | 590 |
| C60E | 1.1221 | 850 | 580 | |
| X20Cr13 | 1.4021 | 750 | 550 | |
| X17CrNi16-2 | 1.4057 | 750 | 550 | |
| X5CrNi18-10 | 1.4301 | V2A | 520 | 210 |
| X2CrNiMo17-12-2 | 1.4404 | V4A | 520 | 220 |
| X2CrNiMoN17-13-3 | 1.4429 | 580 | 295 | |
| 30 crnimo8 | 1.6580 | 1250 | 1050 | |
| 34 crmo4 | 1.7220 | 34 crmo4 | 1000 | 800 |
| 42 crmo4 | 1.7225 | 1100 | 900 | |
| S420N | 1.8902 | StE420 | 520 | 420 |
Common problems about the tensile strength
The tensile strengthRefers to the material before permanent deformation or fracture can withstand maximum tensile stress.As a result, the tensile strength is one of the important material performance evaluation material strength characteristic values.The higher the tensile strength of the material, the greater its resistance to tensile force.
Tensile strength usually in Mpa (Mpa) or Newton per square millimeter (N/mm squared) as a unit for measuring.It says stretched or torn some material need how much force per unit area.
According to the test start at maximum tensile force Fm and sample cross section area is calculated by the tensile strength:
The tensile strength RmF = maximum tensile forcem/ sample cross sectional area S0
The tensile strength in MPa (MPa) or N/mm squared.