原奥氏体晶粒尺寸对珠光体钢组织及韧性的影响

发布时间：2018-07-01 21:50

本文选题：珠光体 + 奥氏体晶粒尺寸　；参考：《材料导报》2017年02期

【摘要】：探索了奥氏体晶粒尺寸对珠光体等温转变组织特征以及对韧性性能的影响规律。研究表明,在相同等温转变温度下,珠光体片层间距无明显变化,随奥氏体晶粒尺寸的增加,先共析铁素体量减少而珠光体团尺寸增加。珠光体断裂韧性受控于裂纹前沿塑性影响区尺寸(1~2)δc,其中δc为临界裂纹张开位移,当原奥氏体晶粒大于(1~2)δc时,裂纹扩展阻力主要来自穿越珠光体片层α、θ相的颈缩、破断。当原奥氏体晶粒尺寸接近或小于(1~2)δc时,裂纹主要沿晶界、珠光体团界、α+θ片层界面扩展,通过扩展路径发生多次弯折消耗能量,随原奥氏体晶粒尺寸增加,准静态断裂韧度J变化幅度较小。而冲击韧性缺口前沿塑性影响区远大于原奥氏体晶粒,大角度晶界将促使裂纹的转折而提高扩展阻力,提高裂纹前沿塑性区大角度晶界密度有利于提高冲击功,冲击韧性Ak随晶粒尺寸的增加显著下降。
[Abstract]:The effect of austenite grain size on the microstructure and toughness of pearlite isothermal transformation was investigated. The results show that the lamellar spacing of pearlite does not change obviously at the same isothermal transition temperature. With the increase of austenite grain size, the amount of preeutectoid ferrite decreases and the size of pearlite cluster increases. The fracture toughness of pearlite is controlled by the size of (1 / 2) 未 c, where 未 c is the critical crack opening displacement. When the original austenite grain is larger than (1 / 2) 未 / c, the crack propagation resistance is mainly due to the necking and breaking through 伪, 胃 phases of the pearlite lamellae. When the grain size of the original austenite is close to or less than (1 / 2) 未 c, the crack mainly propagates along the grain boundary, the pearlite cluster boundary, the 伪胃 lamellar interface, and the energy is consumed by multiple bending through the propagation path, which increases with the grain size of the original austenite. The change of quasi-static fracture toughness J is relatively small. However, the plastic influence zone at the notch front of impact toughness is much larger than the original austenite grain, and the large angle grain boundary will promote the crack turning and increase the propagation resistance, and increase the large angle grain boundary density in the plastic zone of the crack front to improve the impact energy. The impact toughness Ak decreases with the increase of grain size.
【作者单位】：贵州大学材料与冶金学院;贵州省材料结构与强度重点实验室;
【基金】：国家自然科学基金(51461007;51361004) 贵州省重大应用基础研究项目([2014]2003)
【分类号】：TG142.1

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