摘要
以微合金管线钢X70为研究对象,在Gleeble1500热模拟机上,进行了不同形变量和冷却速度对合金相变行为及组织细化影响的研究。实验结果表明,形变量和冷却速度的增加,有助于针状铁素体的形成及细化。管线钢中针状铁素体组织典型的形貌为非常微细的亚结构、高位错密度以及部分细板条铁素体,基体上弥散分布着M/A岛和渗碳体。同时可以观察到在铁素体晶粒边界和铁素体晶粒内部有相的析出。可见,针状铁素体组织细化的机制主要有形变诱导铁素体、铁素体的动态再结晶和相的析出抑制晶粒长大。
The effect of strain amount and cooling rate on phase transformation behavior and microstructure refinement were studied on a Gleeble 1500 thermomethanical simulator using a low carbon low alloy pipeline steel X70. It is found that increasing of strain amount or accelerating of cooling rate improve the formation and refinement of acicular ferrite. The typical features of the acicular ferrite is of very fine sub-structure, high dislocation density and ultra-fine grains in thin lath shape. Precipitating of small M/A islands and cementite on matrix of the laths was observed by TEM analysis. On the other hand, the precipitated phases are found at the boundary and inner of ferrite. The results show that the mechanism of grain refinement for low alloy steels is different from that of low carbon steel, it includes strain induced ferrite, ferrite recrystallization and growth of ferrite hindered by the precipitation of the second phase.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2006年第6期99-102,107,共5页
Transactions of Materials and Heat Treatment
关键词
晶粒细化
针状铁素体
岛状组织
析出相
grain refinement
acicular ferrite
island microstructure
precipitate phase
