Work-hardening Behavior and Evolution of Dislocation-microstructures in High-nitrogen Bearing Austenitic Steels
Work-hardening Behavior and Evolution of Dislocation-microstructures in High-nitrogen Bearing Austenitic Steels
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高氮奥氏体钢的加工硬化行为和位错微观结构的演变
DOI：
10.2355/isijinternational.38.474
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发表时间：
1998
影响因子：
1.8
通讯作者：
Y. Tomota
中科院分区：
文献类型：
--
作者：
S. Kubota;Yu Xia;Y. Tomota
利用透射电镜研究了高氮奥氏体钢在室温变形过程中的组织演变，以弄清高含氮奥氏体钢高加工硬化的原因。采用三种SUS316L型钢（含0.02 ~ 0.56质量%氮）和18Mn-18Cr（护环）型钢（含0.51 ~ 0.84质量%氮）在室温下进行拉伸试验。结果表明，随着氮浓度的增加，屈服强度和加工硬化均增加。在高氮钢中，变形开始时形成平面位错阵列，经常出现多偶极子。然后，它们重叠形成位错壁，同时这些位错阵列或壁在它们的交叉处可能通过lomo - cottrell反应的作用而相互固定。位错壁在进一步变形中发挥类似晶界的作用。在严重变形的试样中观察到的微观结构看起来像精细的八面体网格结构。因此，在塑性变形试样中，高含氮钢中的位错密度要比低含氮钢中的位错密度高得多。
Microstructural evolution during deformation at room temperature has been studied by means of transmission electron microscopy to make clear the reason for high work-hardening in high-nitrogen bearing austenitic steels. Tension tests were carried out at room temperature using three SUS316L type steels bearing 0.02 to 0.56 mass% nitrogen and 18Mn-18Cr (retaining ring) type steels bearing 0.51 to 0.84 mass% nitrogen. It is found that both yield strength and work-hardening increase with increasing nitrogen concentration. In high-nitrogen bearing steels, planar dislocation-arrays are formed in the beginning of deformation, frequently showing multi-dipoles. Then, they overlap to make dislocation-walls and at the same time such dislocation-arrays or walls are pinned each other presumably by operation of Lomer-Cottrell reaction at their intersections. The dislocation-wall is expected to play a role similar to grain boundary for further deformation. Microstructure observed in a heavily deformed specimen looks like fine octahedral grid-structure. Thus, dislocation density in a plastically deformed specimen becomes much higher in high-nitrogen bearing steelsthan in a low-nitrogen bearing steel in which dislocation-cell structure is evolved.