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一、国内外概况 某些形状复杂而尺寸较大,要求精确的模具对变形要求很严格,变形超过规定往往报废而不能使用。空冷微变形钢能满足这方面的要求。这类钢的淬透性很高,因而在缓慢冷却的条件下,甚至在空气中冷却也可以淬硬,通过对成分的控制可以在淬火和回火后改变残余奥氏体的数量以得到极小的变形。在空气中冷却时,内应力很小,有利于减少变形,当形状比较规则,在空气中冷却时,表面及中心的冷却速度几乎相同,这是因为在空气中冷却时,表面热辐射和内部的热传导相同,这样心部和表面几乎有相同的硬度,最大残余应力比水或油冷要小很多,为水冷时的1/20,形状复杂时空冷更为有利。这类钢按成分可分为高碳高铬类(Cr12型)、高碳中铬类(Cr6WV、A2等)及含锰较高的一类。本文介绍的是含锰较高的一类。
First, the general situation at home and abroad Some complex shape and larger size, the exact requirements of the deformation of the mold is very strict, deformation often scrapped and can not be used. Air-cooled micro-deformation of steel to meet this requirement. The hardenability of this type of steel is so high that it can be hardened even under air cooling in a slowly cooled condition. By controlling the composition, the amount of retained austenite can be varied after quenching and tempering to obtain a Small deformation. Cooling in air, the internal stress is small, help to reduce the deformation, when the shape is relatively regular, cooling in air, the surface and the center of the cooling rate is almost the same, because in the air cooling, the surface heat radiation and internal Of the same heat conduction, so that the heart and the surface almost the same hardness, the maximum residual stress is much smaller than water or oil-cooled, water-cooled 1/20, the shape of complex space-time cold is more favorable. According to the composition of these steels can be divided into high-carbon high chromium (Cr12 type), high-carbon chromium (Cr6WV, A2, etc.) and a higher manganese content. This article describes a higher manganese category.