Production process of aluminum profiles
Name

Symbol

Unit

Meaning

Remarks

Proportional limit

δp

MPa

During the stretching process, the maximum stress between the stress and strain is proportional to the strain. The maximum limit load Pp at this stage divided by the original crosssectional area of the test bar is the proportional limit

1 kgf/mm2 = 9.80665MPa 1 MPa = 0.10197kgf/mm2 ：PSI ：lb/in2 KPSI = 1000PSI =6.896MPa

Elastic limit

δe

MPa

During the loading process, the maximum stress without plastic deformation


Tensile modulus of elasticity

E

GPa

When the metal bears the tensile load, in the elastic range, when the stress is proportional to the strain, the proportionality coefficient is the tensile elastic modulus

1 kgf/mm2 = 0.0098067GPa 1GPa = 101.97162kgf/mm2

Shear elastic modulus

G

GPa

When the metal is torsion tested in the elastic range, the external force and deformation increase proportionally, that is, when the stress is proportional to the strain, this proportionality factor is called the shear elastic modulus.







Yield strength (Conditional yield strength)

δ0.2

MPa

During the stretching process, the stress obtained by dividing the load at the specified value of the original gauge length when the plastic deformation amount of the gauge length part is generally defined by the original crosssectional area is called the yield strength or conditional yield strength. Generally, the specified value is 0.2% of the original gauge length of the tensile specimen, which is expressed by δ0.2


Compressive yield strength (Conditional yield strength)

δ0.2

MPa

In the compression test, the stress obtained when the residual compression of the gauge portion reaches the value specified in the original gauge length divided by the original crosssectional area is called compressive yield strength or conditional compressive yield strength. The generally specified value is 0.2% of the original gauge length of the compressed sample. Since the direction of the force is opposite to the tensile, the compression yield strength is usually expressed by δ0.2


Shear strength


MPa

When the specimen is sheared, the maximum load on the shear plane divided by the original crosssectional area is called the shear strength. It indicates the maximum ability of the material to resist damage under the action of shear force.


tensile strength

δb

MPa

Under the action of a unidirectional uniform tensile load, the maximum load of the material at break is divided by the stress obtained by the original crosssectional area.


Fatigue limit

δ1

MPa

Under the action of repeated alternating stress, the maximum stress value that the material has endured unlimited cycles without breaking


Fatigue strength

δN

MPa

Under the action of alternating stress, within the specified number of cycles (such as 106, 107, 108, etc.), the maximum stress value that will not cause fracture


Elongation (elongation)

δ5 δ10

%

When the material is stretched, after the sample is broken, the percentage of the length of the gauge length added to the original gauge length. Is the elongation when the gauge length is 5 times the diameter, is the elongation when the gauge length is 10 times the diameter


rate of reduction in area

ψ

%

After the metal sample is broken, the percentage of the crosssectional area of the necking and the original crosssectional area


Impact toughness

αk

J/cm2 or kJ/m2

With a Ushaped notch standard sample of a certain size and shape, when the specified type of testing machine is broken by an impact load, the impact energy consumed per unit crosssectional area at the groove of the sample. It represents the resistance of metallic materials to impact loads.

1 kgf•m/cm2 = 98.0665kJ/m2 1kJ/m2 = 0.010197kgf/cm2

Brinell hardness

HBS


Press the hardened steel ball of a certain diameter into the surface of the sample and hold it under a specified load for a certain period of time. The Brinell hardness of the quotient surface material obtained by dividing the indentation area by its load. The calculation formula is HBS = 2P / лD [D – (D2d2) 1/2] P——Load D——Indenter diameter, mm; d——Indentation diameter, mm

Usually the hardness value is directly checked from the measured indentation diameter

Rockwell hardness

HRB HRF


On the Rockwell hardness machine, a hardened steel ball with a diameter of 1.58 mm is used as the indenter, and the load is the hardness value obtained from the 980N test. Use 1.58mm hardened steel ball as the indenter, the load is the Rockwell hardness value measured by 588N

HRB is often used to measure the hardness value of aluminum alloy after quenching and aging. HRF is used to measure the hardness of aluminum alloy forgings

Micro Vickers hardness

HV


Use a diamond quadrangular pyramid indenter with an angle of 136o to press in the sample with a load of 0.2kgf or less (usually expanded to 1kgf), and the hardness value of the material is expressed by the load per unit area. The instrument is equipped with a metallographic microscope, which is used to measure the microstructure of the alloy and the hardness value of the extremely thin surface layer


density

ρ

g/cm3 or kg/m3

Mass per unit volume of metallic materials


Melting point


℃

The melting temperature when the material changes from solid to liquid


Average linear expansion coefficient

α

µm/(m•k)

The length of an object changes with temperature. Within the specified temperature range, whenever the temperature rises or falls by 1, the length of its unit length of expansion and contraction is called the average linear expansion coefficient.

See Table 15 for calculation formula of expansion and contraction rate

Thermal conductivity (thermal conductivity)

λ

W/(m•℃)

Indicates the ability of an object to conduct heat. When the unit temperature gradient (ΔL / ΔT) is maintained in the object, the heat (Q) flowing through the unit area (A) perpendicular to the heat flow direction within the unit time (t) is expressed

1 cal/(s•cm•℃) = 418.68W/(m•℃) λ=1/A•Q/t•ΔL/ΔT

Specific heat capacity

С

J/(kg•K) or J/(kg•℃)

The heat absorbed by the unit mass of substance when the temperature is increased by 1K degrees during the isobaric process (or isovolumic process) or the heat released by the temperature decreased by 1K degrees

1 kcal/(kg•K) = 4186.8J(kg•K) 1 kcalth/(kg•K) = 4186.8J(kg•K)

Resistivity (specific resistance resistivity)

ρ

Ω•m чΩ•m nΩ•m

A physical constant that characterizes the electrical conductivity of a substance. It is equal to the resistance between the ends of a wire with a length of 1m and a crosssection of 1mm2. It can also be expressed by the resistance between two equal ends of a unit cube

1µΩ•cm = 108Ω•m 1nΩ•cm = 109Ω•m

Conductivity

λ

S/m

The reciprocal of resistivity is called conductivity. Numerically it is equal to the current flowing through a unit area when the conductor maintains a unit potential gradient


Temperature coefficient of resistance

αp

℃1

The ratio of the change in the resistivity of the material to the original resistivity per 1 liter of temperature

