摘要
利用控制冷却速度的凝固实验,研究连铸坯奥氏体不锈钢Cr15Mn9Cu2Ni1N不同冷却速度下的组织和凝固模式。结果表明,缓慢冷却时,显微组织为奥氏体基体上分布着蠕虫状残留铁素体;其凝固模式为全部液相先析出δ铁素体,随后通过固相转变形成奥氏体基体。较高冷却速度时,奥氏体组织有两种形态,一是分布着侧板条残留铁素体的奥氏体,二是圈状的分布在第一种奥氏体晶界的单相奥氏体。分析发现,冷却速度的增加使凝固模式发生如下变化:大部分液相先析出δ铁素体,随后固相转变为奥氏体;剩余液相直接转变为奥氏体。同时发现,氮含量的增加可以减小奥氏体晶粒尺寸。
In order to understand the effect of cooling rate on microstructure and solidification mode of continuous casting slab, a solidification experiments with controllable cooling rate were performed to obtain microstructures of austenitic stainless steel Cr15Mn9Cu2Ni1N. The microstructures obtained with lower cooling rate is austenite base with vermicular residual ferrite, solidification mode for this type of morphology is that primary δ ferrite solidifies from liquid, and transforms to austenite during the subsequent solid-state transformation. When the cooling rate is high, there are two types of austenitic morphologies. One is austenitic base with lathy ferrite, the other is a ring-like single phase austenite. The solidification mode with higher cooling rate changes as follows, primary δ ferrite solidifies from residual liquid and transforms to austenite during the subsequent solid-state transformation, and the residual liquid crystallize as austenite directly. In addition, austenite grain size of steel with higher nitrogen content is smaller.
出处
《铸造技术》
CAS
北大核心
2009年第7期864-867,共4页
Foundry Technology
关键词
奥氏体不锈钢
冷却速度
凝固模式
Δ铁素体
Austenitic stainless steel
Cooling rate
Solidification mode
δ ferrite
