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What are the main materials of the protective box? What are the main functions?

Date:2017/7/21 19:20:31

The ability of protective box materials to resist deformation and fracture under certain temperature conditions and external forces is called mechanical properties of materials. The conventional mechanical properties of boilers and pressure vessels include strength, hardness, plasticity and toughness.

(1) strength: strength refers to the resistance of metal materials to deformation or fracture under external force. Intensity index is decided in the design of important basis of allowable stress, the strength of the commonly used indicators have yield strength sigma S or 0.2 and tensile strength of sigma sigma b, work under high temperature, also consider creep rupture limit sigma n and sigma D.

(2) plasticity: plasticity refers to the ability of metal materials to have plastic deformation before fracture. The plastic index includes: elongation delta, i.e. the relative elongation after the sample pulling. The reduction of cross-sectional area of the section of the sectional area of the sectional area of the fracture area is the reduction of the cross-sectional area. A cold bend (Angle) alpha, which is the Angle measured when the specimen is bent to the first crack in the ramen.

(3) toughness: toughness refers to the ability of metal materials to resist impact load. The toughness is commonly used to hit Ak and impact toughness value alpha k. Α k value or alpha k value in addition to reflect the material shock resistance, and is sensitive to some of the pitfalls of materials, sensitive to reflect the material quality, the macroscopic defects and small changes in the microstructure. And Ak is very sensitive to the brittle transformation of materials, and the cold impact test can check the cold brittleness of steel. A new indicator of material toughness is fracture toughness delta, which reflects the resistance of materials to crack propagation.

(4) hardness: hardness is a performance index to measure the hardness of the material. The hardness test method is more, the principle is different, the hardness value and the meaning are not exactly the same. Is the most commonly used method of static load pressure into the hardness test, namely the brinell hardness (HB) and rockwell hardness (HRA, HRB, HRC), vickers hardness (HV), its value indicates the material's ability to fight hard object into the surface. And the scleroscope hardness (HS) is a test of the backjump, whose value represents the magnitude of the elastic deformation work. Therefore, hardness is not a pure physical quantity, but a comprehensive performance index reflecting the elasticity, plasticity, strength and toughness of the material.

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