在大型锻件中,由于尺寸的原因,不仅在成形时,而且在热处理的加热和冷却时,不可避免地会出现横截面上的温度差。这意味着锻件心部较长时间停留在较高温度下,从而一方面促使晶粒强烈长大,另一方面有可能使锻件心部在冷却阶段长时间保持在转变温度以上。因此,在一般情况下,尤其是锻件心部,晶粒大小无疑会很不一致。锻件中存在的偏析更加强了这种效应。 In large forgings, due to size, a temperature difference across the cross-section inevitably occurs not only during forming but also during heating and cooling of the heat treatment. This means that the forging core stays at a higher temperature for a longer period of time, so that on the one hand the grains grow strongly and on the other hand it is possible for the forging core to remain above the transformation temperature for a long time during the cooling phase. Therefore, under normal circumstances, especially forging heart, the grain size will undoubtedly be very inconsistent. Segregation in forgings reinforces this effect.