Hottest forging streamline and forging ratio

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Forging flow line and forging ratio

there are non-metallic compounds insoluble in the base metal in the ingot. In the process of pressure processing, brittle impurities are usually broken, distributed in granular or chain shape along the main elongation direction of the metal, and plastic impurities are distributed in strips along the grain elongation direction. This directional structure is called forging streamline (also known as flow pattern), which makes metal properties anisotropic

forging streamline increases the plasticity and toughness of forgings in the longitudinal direction and decreases in the transverse direction; The strength has little difference in different directions. When designing and manufacturing parts, the direction of the maximum normal stress when the parts are working should be parallel to the direction of the streamline, the direction of the maximum shear stress should be perpendicular to the direction of the streamline, and the distribution of the streamline should be consistent with the outer contour of the parts without being cut off. For example, if the bar material is directly used to manufacture screws by cutting, the quality of the screws is poor and the service life is low; The screws made by local upsetting have good quality and long service life. For another example, the crankshaft adopts the full streamline forging method, so that the streamline is continuously distributed along the crankshaft shape, which improves the service life and reduces the material consumption

2. Forging ratio

in forging production, the degree of metal deformation is expressed by forging ratio. The forging ratio and the forging ratio y drawing length of forging related processes are:

y drawing length =a0/a=l1/l0

it still has various problems. In the formula: A0, a - the cross-sectional area before and after blank drawing

l1, l0 - length of blank before and after drawing

the forging ratio has a greater impact on the mechanical properties of forgings, which has reached 40000 tons by 1986. When the forging ratio increases, the strength sb of forgings has little difference in transverse and longitudinal directions. When the forging ratio reaches 2, the plasticity of forgings is significantly improved; When the forging ratio is 2 ~ 5, the mechanical properties are anisotropic, the longitudinal plasticity is improved, and the transverse plasticity begins to decline; When the forging ratio exceeds 5, the longitudinal properties are no longer improved, while the transverse plasticity decreases sharply

therefore, it is very important to select the appropriate forging ratio. When forging with steel ingot as blank, the forging ratio of carbon structural steel is 2 ~ 3, and that of alloy structural steel is 3 ~ 4. When forging with steel as blank, because its internal structure and mechanical properties have been improved, the forging ratio is generally 1.1 ~ 1.3 according to the new national standard inspection content and project requirements provided by the national fire protection building materials quality supervision and inspection center

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