Common terms of hardware

2022-07-26
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Practical knowledge: common hardware terms

a yield point (physical yield strength):

Code: σ s; Unit: MPa (or n/mm2)

introduction: refers to the ability of a metal material to resist external forces when its deformation (elongation) suddenly increases greatly when it is subjected to a certain degree of tension

b specified residual elongation stress (yield strength, conditional yield strength):

Code: σ r; Unit: MPa (or n/mm2)

introduction: it refers to the

stress when the residual elongation of the gauge part reaches a specified value after the metal material is removed; When the specified value is 0.2%, the code is written as σ R0.2

c specified non proportional elongation stress:

Code: σ P real time display of water volume curve; Unit: MPa (or n/mm2)

introduction: refers to the stress when the non proportional elongation of gauge length reaches a specified value during the tensile process of metal materials; When the specified value is 0.01%, the code is written as σ p0.01。

common terms hardness

introduction: the ability of a material to resist hard objects pressing into its surface. Hardness can be divided into the following types according to different measurement methods:

Brinell hardness:

Code: HBS (hardened steel (3) installed with new sealing ring and global measurement) or HBW (cemented carbide ball measurement), which is also generally written as HB

unit: none

introduction: press a hardened steel ball or cemented carbide ball with a certain diameter into the material surface under a certain load, remove the load after holding it for a specified time, measure the indentation on the material surface, and then calculate the hardness according to the formula

Rockwell hardness:

Code: hr

unit: none

introduction: press the hardened steel ball or conical diamond indenter with a vertex angle of 1200 into the material surface with a certain load, and then calculate the hardness based on the depth of the pit on the material surface

there are many scales for Rockwell hardness, the common ones are:

a. scale C: Code HRC, the hardness obtained by using the total load of 1471.1n (150kgf) of 3 artificialvitreousbody materials and diamond indenter It is suitable for hardness measurement of hardened and tempered steel, quenched steel and other hard materials

b. scale a: Code HRA, hardness obtained by 588.4n (60 KGF) total load and diamond indenter It is suitable for hardness measurement of surface hardened steel, carburized steel or cemented carbide

c. scale B: Code HRB, hardness obtained by using 980.7n (100 KGF) total load and 1.588mm diameter quenched steel ball indenter. It is suitable for hardness measurement of soft materials such as non-ferrous metals, annealed steels and normalized steels

surface Rockwell hardness:

Code: hr

unit: none

introduction: the test principle is the same as Rockwell hardness. It is applicable to the determination of hardness of surface and grade steel sheets and non-ferrous metals treated by carburizing and nitriding on the steel surface. There are also many scales for such hardness: A. scale 15N: Code hr15n, the hardness obtained by 147.1n (15 KGF) total load and diamond indenter

b. scale 30n: Code hr30n, the hardness obtained by 294.2n (30 KGF) total load and diamond indenter

c. scale 45N: Code hr45n, the hardness obtained by 441.3n (45 KGF) total load and diamond indenter

d. scale 15t: Code hr15t, Hardness obtained by 147.1n (15 KGF) total load and 1.588mm diameter hardened steel ball indenter

e. scale 30t: Code hr30t; hardness obtained by 294.2n (30 KGF) total load and 1.588mm diameter hardened steel ball indenter

f. scale 45t: Code hr45t; early signatures obtained by 294.2n (45 KGF) total load and 1.588mm diameter hardened steel ball indenter include refined steel, gold Hardness of platinum and platinum plates

Vickers hardness:

Code: hv

unit: none

introduction: press the square conical diamond with an included angle of 1360 on the opposite surface into the material surface with a load of 49.03~980.7n. After maintaining it for a specified time, measure the diagonal length of the indentation, and then calculate the hardness according to the formula. It is suitable for hardness measurement of large workpieces and deep surface layers. Vickers hardness still has small load Vickers hardness, test load 1.961~

common terms strength limit (strength)

Code: σ; Unit: MPa (or n/mm2)

introduction: it refers to the maximum capacity of metal materials to resist external force damage. Strength is divided into:

compressive strength: Code σ BC, refers to the strength limit when the external force is pressure

bending strength: Code σ BB, refers to the strength limit when the external force is perpendicular to the material axis and makes the material bend after action

shear strength: Code σ c. Refers to the strength limit when the external force is perpendicular to the material axis and acts as a shear on the material

tensile strength: Code: σ b. Refers to the strength limit when the external force is tensile force

common terms elastic limit, elongation and reduction of area

a elastic limit

Code: σ e; Unit: MPa (or n/mm2)

introduction: refers to the deformation (elongation) of the metal material will disappear and return to its original state when the external force (tension) is removed. The elastic limit refers to the ability of the metal material to resist the external force of this limit

b elongation (elongation)

Code: δ; Unit:%

introduction: refers to the percentage of the elongation length of the test bar to the original length when the metal material is broken under the action of external force (tension). The elongation is divided into: the elongation obtained from the short test bar, code is δ 5. The gauge distance of the test bar is equal to the elongation obtained by 5 times the diameter of the long test bar. The code is δ 10. The gauge distance of the test bar is equal to 10 times the diameter C section shrinkage (shrinkage)

Code: Ψ; Unit:%

introduction: it refers to the percentage of the reduced area of the cross-section to the original cross-section area when the metal material is fractured under the action of tension

common terms impact absorption energy and impact toughness

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