How to choose the degree of metal deformation in forging process?

China forging talent network: the shape size will change after forging punching, generally the height direction size becomes smaller, the radial size becomes larger.

Forging ratio is a method to express the degree of metal deformation during forging. The forging ratio is expressed as the ratio of the cross-sectional area before and after the metal deformation. The calculation method of forging ratio is different for different forging process.

1. Drawing length forging ratio: ratio of cross-sectional area before drawing length to cross-sectional area after drawing length

2. Upsetting forging ratio: ratio of cross-sectional area after upsetting and cross-sectional area before upsetting

With the increase of forging ratio, the internal pores are pressed together, the cast dendrites are broken, and the longitudinal and transverse mechanical properties of the forging are improved obviously. However, when the forging section ratio of drawing length is greater than 3-4, with the increase of forging section ratio, obvious fiber structure is formed, which makes the plastic index of transverse mechanical properties drop sharply, leading to the forging anisotropy. If the forging section ratio is too small, the forging can not meet the performance requirements, too large will increase the forging workload, but also cause anisotropy. Therefore, the reasonable choice of forging is an important topic, here should also consider the forging deformation of the uneven problem.

Forging ratio is usually measured by the degree of deformation when drawing length. Is the ratio of the length to the diameter of the material you want to shape or the ratio of the cross-sectional area of the raw material (or prefabricated blank) before forging to the cross-sectional area of the finished product after forging. The forging ratio affects the mechanical properties of the metal and the quality of the forging. Increasing the forging ratio is beneficial to improve the microstructure and properties of the metal, but too large forging ratio is not beneficial.

The principle of forging ratio selection is to choose smaller parts as far as possible under the premise of ensuring various requirements of forging parts. Forging ratio is generally determined according to the following conditions:

1, high quality carbon structural steel and alloy structural steel free forging on the hammer: for shaft forgings, direct forging by the ingot, according to the main section of the forging ratio should be ≥3; According to the flange or other protruding parts of the forging ratio should be ≥1.75; When using billet or rolling, according to the main section of the forging ratio is ≥1.5; According to the flange or other protruding parts of the forging ratio should be ≥1.3. For ring forgings, forging ratio should generally be ≥3. For disc forgings, the upsetting forging ratio is ≥3; On other occasions, upsetting forging than general should > 3, but the last procedure should be. 2.

2. The high alloy billet cloth should not only eliminate its organizational defects, but also make the carbide in it have a more uniform distribution, so it must take a larger forging ratio. The forging ratio of stainless steel can be selected as 4-6, while the forging ratio of high speed steel is 5-12.