| serial | name | amount of symbols | unit symbol | meaning | A | strength | strength of the metal in the external force, the resistance to plastic deformation and fracture. | 1 | tensile strength | σb | MPa | metal tensile pull off before the bear maximum load the specimen cross-sectional area of the ratio known as the tensile strength: Pb σb = - Fo Where Pb - sample pulled off before the maximum load (N) Fo - sample of the original cross-sectional area (mm ²) | 2 | bending strength | σbb | MPa | The sample is located in the middle of a concentrated load of two bearing, it is broken, the broken cross section to withstand the maximum positive pressure 8PL Round specimen: σbb = - πd3 8PL Rectangular specimen: σbb = - 2bh2 Where P - the sample to withstand the maximum concentrated load (N) L - the span between the two bearing points (mm) d - outer diameter of the circular specimen cross section (mm) b - the width of the rectangular cross-section sample (mm) h - the width of the rectangular cross-section sample (mm) | 3 | compressive strength | σbc | MPa | Materials under pressure is not broken, the crack can withstand the maximum positive pressure, known as the compressive strength Pbc σbc = - Fo Where Pbc - sample suffered the largest concentrated load (N) Fo - the original specimen cross-sectional area (mm ²) | 4 | shear strength | r, σr | MPa | Cut section has an average stress in the specimen is cut prior to withstand the maximum load under: P Twin Shear: σr = -; 2fo P Simple shear: σr = -; Fo Where P - when the maximum shear load (N) Fo - The cut parts of the cross-sectional area (mm ²) | 5 | torsional strength | τb | MPa | refers to the external force is the ultimate strength of the torsional force 3Mb τb ≈ - (for steel) 4Wp Mb τb ≈ - (cast iron) Wp Where Mb - to reverse the torque (N · mm) Wp - torsion of the specimen cross-section pole section coefficient (mm ²) | 6 | yield point | σs | MPa | metallicity sample during the tensile load no longer increases, while the sample continues to deform the phenomenon known as the "yield". Yield stress when the phenomenon occurs, called the yield point or yield limit: Ps σs of = - Fo Where Ps - yield load (N) Fo - sample of the original cross-sectional area (mm ²) | 7 | yield strength | σ0.2 | MPa | metal material of some of the yield is not obvious, the determination of the yield point is more difficult, often a 0.2% permanent deformation stress for the yield point, called the yield strength or conditions yield limit: Of P0.2 σ0.2 = - Fo Of P0.2-where - the sample to produce permanent deformation of 0.2% of the load (N) Fo - sample of the original cross-sectional area (mm ²) | 8 | lasting strength | σ0.2 / time (h) | MPa | metal materials in high temperature conditions, after a stress fracture of the specified time, known as the persistent strength. Commonly referred to as persistent strength in a certain temperature conditions, the specimen through the breaking strength after 105h. | 9 | creep strength | temperature σ - Should be variable / time | MPa | metal materials above a certain temperature by the stress, even if the stress is less than the yield strength, the specimen will slowly increase over time to plastic deformation, this phenomenon is called creep. Within a given temperature and a specified time, the specimen to produce a certain creep stress deformation known as creep strength, for example: 500 σ - = 100MPa, 1/100 000 Said materials after 105h at 500 ° C variable to 1% creep strength of 100MPa. The creep strength of the material in the plastic deformation resistance under high temperature under long-term load performance. | Two | flexibility | flexibility refers to the metal deformation under external force, when the external forces cancel and then return to its original shape and size of a feature. | 1 | modulus of elasticity | E | GPa | in the elastic range, metal tensile test, external, and change the formation of the proportion of growth, stress and strain is proportional to the scale factor is called the modulus of elasticity , also known as being the modulus of elasticity. | 2 | shear modulus | G | GPa | metal in the elastic range, when the torsion test, external, and change the formation of the proportion of growth, the relationship between stress and strain is proportional to this scale factor is called the elastic modulus, also known as being the elastic modulus. | 3 | elastic limit | σe | MPa | metal to maintain the elastic deformation of the maximum stress called the elastic limit. | 4 | proportional limit | σp | MPa | elastic deformation stage, the metal material exposure and strain can be maintained proportional to the maximum stress, called the proportional limit: Pp σ0.2 = - Fo Pp - where the provisions of the proportional limit load (N) Fo - sample of the original cross-sectional area (mm ²) | Three | plastic | called plasticity refers to the metal material in the external force, the permanent deformation without rupture of the ability. | 1 | elongation | δ | % | metal materials in tension, the specimen fractured, the percentage of its gauge Division increased the length of the original gauge length. δs is the elongation when the gauge is 5 times the diameter, the δ10 when the gauge is 10 times the diameter elongation. | 2 | section shrinkage | ψ | % | metal fractured necking at the cross-sectional area of the maximum reduction in the percentage of the original cross-sectional area. | 3 | Poisson's ratio | μ | / | isotropic material, Poisson's ratio: the amount of the sample in the single-phase tension, transverse relative shrinkage and the relative axial stretch length ratio of the amount: E μ = - 1 2G Where E - modulus of elasticity (GPa) G - shear modulus (GPa) | Four | toughness | so-called toughness without destroying the ability of metallic materials under impact (dynamic load). | 1 | impact toughness | αKU, or αKV | J/cm2 | impact toughness is the assessment of the metal by the impact resistance of mechanical properties of materials under dynamic load, are usually large energy impact value ( αKU or αKV) as a standard, it is the use of a certain size and shape of the standard sample, in the Charpy impact test machine at up to test. Test results, the power consumption to thrust on the specimen (AKU AKV) and the cross section at the cross-sectional area (F) ratio to measure the size. | 2 | absorbed energy | AKU AKV | J | αK value size depends not only on the material itself, but also with the sample size, different shape changes and test temperature changes αK value is only a relative index. Many countries in the international impact absorbed energy of AK as indicators of the impact toughness. AKU. αKU = -; F AKU. αKV = -; F Where αKU - Charpy U-notch specimen impact value (J/cm2) αKV - Charpy V notch specimen impact value (J/cm2) Power consumed in the thrust than the U-shaped notched specimens of AKU. - Summer (J) Power consumed in the thrust than the V-shaped notched specimens of AKV - Summer (J) F - notch at the cross-sectional area (cm ²) | Five | Fatigue | metal material below the ultimate strength, long-term under alternating load (ie, the size and direction of repeated changes in the role of the load), does not occur in significant plastic deformation and sudden rupture of the phenomenon known as fatigue. | 1 | fatigue limit | σ-1 | MPa | metallic materials under repeated or alternating stress cycles (N) stress cycle still occur can withstand the maximum stress in the break known as the fatigue limit. | 2 | fatigue strength | σN | MPa | metallic materials under repeated or alternating stress cycles (N) after the fracture can bear the stress and fatigue, known as strength. At this point, N, known as the fatigue life. Some metallic materials under repeated or alternating stress, the fatigue limit, commonly used in fatigue strength, said. | Six | Hardness | refers to the hardness of the metal against hard object pressed into the surface of the ability. Hardness is not a purely physical quantity, but rather reflects a comprehensive performance indicators of resilience, strength, plasticity. | 1 | Brinell hardness | HBS | / | a certain diameter of the sphere (ball or carbide ball into the surface of the sample to the corresponding test beat to keep time by the provisions of removable test force, the measured diameter of the surface indentation hardness values calculated using the ball of hardness less than or equal to 450HBS; carbide ball of hardness greater than 450HBW | 2 | Rockwell hardness | HRA HRB Of HRC HRD HRE and The HRF Of HRG Of HRH HRK | / | diamond cone or steel ball indenter to the initial test force and total test force, pressed into the surface of the sample The removable main test force after the specified hold time, measuring the residual indentation depth increment to calculate the hardness value. Rockwell hardness test points A, B, C, D, E, F, G and H, K, ruler. | 3 | Vickers hardness | HV | / | a rectangular body with diamond indenter 49.03-980.7N test force pressure on the sample surface, after the specified hold time, removable test force measured indentation diagonal length of the calculated hardness value. | 4 | Shore | HSC HSD in | / | diamond or steel ball punch a certain height, fell on the surface of the sample, the measured red head back to the jump height calculation of hardness values. Visual hardness of the hardness symbol for the HSC, indicating that the hardness of the hardness symbol for HSD in. | Seven | Friction reduction and wear resistance | 1 | friction factor | μ | / | contact with each object, as the relative movement can cause friction, caused by the friction resistance is called friction. Friction law the friction (F) is usually applied in the friction parts of the vertical load (N) ratio, called the friction factor. F μ = - N Where: F - friction (N) N-imposed vertical load on the friction parts (N) | 2 | the amount of wear | W V | g cm 3 | specimen under specified test conditions after a certain time or certain distance friction, the specimen is rubbed off the weight (g) or volume ( cm 3) the amount, called the amount of wear (or wear volume), known as the volume of wear V rubbed off volume. | 3 | relative wear coefficient | ε | / | simulation wear testing machine under the same conditions as the standard sample, the standard sample the amount of wear and 65Mn (52-53HRC) the ratio of the absolute amount of wear in the determination of material, known as the relative wear coefficient of the material being tested. |