Microstructural stability of ultrafine grained low-carbon steel containing vanadium fabricated by intense plastic straining
Microstructural stability of ultrafine grained low-carbon steel containing vanadium fabricated by intense plastic straining
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强塑性应变制备超细晶含钒低碳钢的微观结构稳定性
DOI：
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发表时间：
2001
期刊：
影响因子：
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通讯作者：
D. Shin
中科院分区：
文献类型：
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作者：
Kyung;Yong;D. Shin
两个等级的低碳钢，一个含有钒和其他没有钒，进行等通道转角挤压（ECAP）在623 K的有效应变高达10.4。在等径角挤压之后，在693至873 K的温度范围内对两种挤压钢进行1小时的静态退火处理。通过比较两种钢退火过程中的组织演变和拉伸性能，研究了添加钒对强塑性变形制备的超细晶（UFG）低碳钢热稳定性的影响。对于没有钒的钢，粗再结晶铁素体晶粒出现在退火温度高于753 K，并观察到由此产生的强度下降。对于含钒钢，亚微米级铁素体晶粒尺寸和抗拉强度保持到813 K。含钒钢的热稳定性和机械稳定性的提高归因于其独特的显微组织，该组织由不明确的珠光体团和超细铁素体晶粒以及均匀分布的纳米尺寸的铁素体颗粒组成。这种显微组织是由下列因素的综合作用造成的：（a）由于钒对提高钢的再结晶温度的作用，保持了高位错密度，提供了有效的扩散途径;以及（B）通过碳原子的增强扩散在铁素体晶界处析出细小的铁素体颗粒（这些碳化物是通过剧烈的塑性应变从珠光体中溶解出来的）沿沿着铁素体晶界和位错核心。
Two grades of low-carbon steel, one containing vanadium and the other without vanadium, were subjected to equal channel angular pressing (ECAP) at 623 K up to an effective strain of ∼4. After equal channel angular pressing, a static annealing treatment for 1 hour was undertaken on both pressed steels in the temperature range of 693 to 873 K. By comparing the microstructural evolution during annealing and the tensile properties of the two steels, the effect of the addition of vanadium on the thermal stability of ultrafine-grained (UFG) low-carbon steel fabricated by intense plastic straining was examined. For the steel without vanadium, coarse recrystallized ferrite grains appeared at annealing temperatures above 753 K, and a resultant degradation of the strength was observed. For the steel containing vanadium, submicrometer-order ferrite grain size and ultrahigh strength were preserved up to 813 K. The enhanced thermal and mechanical stabilities of the steel containing vanadium were attributed to its peculiar microstructure, which consisted of ill-defined pearlite colonies and ultrafine ferrite grains with uniformly distributed nanometer-sized cementite particles. This microstructure resulted from the combined effects of (a) the preservation of high dislocation density providing an effective diffusion path, due to the effect of vanadium on increasing the recrystallization temperature of the steel; and (b) precipitation of fine cementite particles at ferrite grain boundaries through the enhanced diffusion of carbon atoms (which were dissolved from pearlitic cementite by severe plastic straining) along ferrite grain boundaries and dislocation cores.