摘要
本文研究了GDL-1型高强韧性贝氏体钢,在空冷状态下的回火冲击性能变化以及对应的显微组织和断口金相特征.结果表明,该钢经920℃加热空冷后获得条束状过渡形态的贝氏体加少量岛状贝氏体组织.在400℃-600℃的温度回火,分布于BF条束间的亚稳态残留奥氏体开始大量分解形成沿条束界连续分布的碳化物,在BF条内的高密度位错区也诱导析出碳化物,导致在条束界产生高应力集中而引发准解理和解理开裂,出现不可逆回火脆性,冲击能量显著降低.由于钢中的Si和Mn在原奥氏体晶界偏聚,抑制碳化物析出.在原奥氏体晶界未能沉淀出连续分布的碳化物,因此未见沿晶解理开裂特征,对应的断口金相呈条形准解理和解理的特征,其尺寸分别与BF条和束尺寸相吻合.该材料的不可逆回火脆性出现的温度范围与大多数合金结构钢相比提高约200℃.
In this paper, the high strength and toughness GDL- 1 bainite steel was studied under air-cooling condition for the change of tempering impact properties, corresponding microstructure and fractograph characteristics. The results show that the microstructure of the steel is the mixture of lath transition bainite and few islands bainite after heat treatment at 920℃ and air - cooling. The retained austenite which is distributed in lath of BF begins to decompose massively and forms successive carbides along the bunch boundary after tempered in the rang of 400℃-600℃, and carbides are also induced in high density dislocation area of BF, resulting in concentrated stress, initiating accurate cleaves and cleaves dehiscence and forming irreversible temper brittleness to reduce remarkably the impact energy. Because Si and Mn partially gather in the original austenite crystal boundary, carbides can be restrained to induce. So the successive carbides cannot deposit in the original austenite crystal boundary. And cleaving characteristic along the crystal has not been found. The corresponding fractographs appear the characteristic of strip accurate cleaves and quasi cleaves. Its size is consistent with the strip and lath of BF. Compared with other structural steel, the temperature range of irreversible temper brittleness of GDL - 1 steel will be enhanced about 200℃.
出处
《贵州科学》
2007年第1期13-16,26,共5页
Guizhou Science
基金
科技部创新基金
贵州省发改委产业化项目
关键词
贝氏体钢
回火脆性
冲击能量
碳化物析出
bainite steel
temper brittleness
impact energy
carbide precipitation
作者简介
梁益龙，教授．发表论文20余篇，获贵州省科技进步二等奖等奖励5项，发明专利4项
