30MnCrNiMoB钢绝热剪切带的显微观察与微结构分析

Microscopic Structures of Adiabatic Shear Band in 30MnCrNiMoB Steel

３０ＭｎＣｒＮｉＭｏＢ低合金钢板（１５ｍｍ厚）经９００℃淬火．４００℃×２ｈ回火，在模拟穿甲弹射击下，背强为４３７ｍ／ｓ．弹坑周围用硝酸酒精腐蚀可观测到白亮的绝热剪切带（ＡＳＢ）．带的尖端分布着向基体发散的流变线．透射电镜观察显示带中为严重碎化的马氏体，其衍射花样几乎等于多晶环．绝热剪切带内除马氏体外尚有细小碳化物．本文证实这种绝热剪切带是一种形变带，并测得最大剪切应变为１９００％．

The 15 mm-thick 30MnCrNiMoB low-alloy steel plate was quenched at 900℃ then tempered at 400C for 2 hours. It was shot by imitative armour-piercing bullets at a protection limit of 437 m/s. Whitelustet adiabatic shear bands bete thus found near to craters after etching out the hitting point with Nital solution,with now lines spread out around the band tip and extended into the matrix. By electron microscopy,such bands are mainly composed of highly fragmental martensites with their diffraction patterns similar to polycrystallines,i.e. discrete diffraction rings, In addition.fine carbides were also found in such bonds.It was verified that such adiabatic shear bands were of deformed type with maximum shear strain of 1900%.