Properties of UFG HSLA Steel Profiles Produced by Linear Flow Splitting
Properties of UFG HSLA Steel Profiles Produced by Linear Flow Splitting
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线性流分割生产的 UFG HSLA 钢型材的性能
DOI：
10.4028/www.scientific.net/msf.584-586.661
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
C. Müller
中科院分区：
文献类型：
--
作者：
E. Bruder;T. Bohn;C. Müller
线性分流成形是一种新型的板料分支结构冷成形工艺。它在加工区引起严重的塑性应变，导致形成UFG显微组织，并增加法兰的硬度和强度。加工区中的固有变形梯度导致显微组织和机械性能的陡峭梯度。本文介绍了线性分流处理的高强度低合金钢（ZStE 500）的UFG组织梯度和力学性能，以及根据Ludwikeequation由硬度测量计算局部强度。为了研究UFG微观结构的热稳定性，选择低于再结晶温度的热处理。利用EBSD技术研究了梯度超细晶组织的粗化过程和小角度晶界与大角度晶界之比的变化。结果表明，热处理可以导致晶粒细化，由于一个强大的破碎的细长晶粒，而只有很少的粗化在横向方向上发生。观察到UFG微观结构以及机械性能中的梯度的平滑化。
Linear flow splitting is a new cold forming process for the production of branched sheet metal structures. It induces severe plastic strain in the processing zone which results in the formation of an UFG microstructure and an increase in hardness and strength in the flanges. Inbuilt deformation gradients in the processing zone lead to steep gradients in the microstructure and mechanical properties. In the present paper the gradients in the UFG microstructure and the mechanical properties of a HSLA steel (ZStE 500) processed by linear flow splitting are presented, as well as a calculation of local strength from hardness measurements on the basis of the Ludwikequation. In order to investigate the thermal stability of the UFG microstructure heat treatments below the recrystallization temperature were chosen. The coarsening process and the development of the low angle to high angle grain boundary ratio in the gradient UFG microstructure were monitored by EBSD measurements. It is shown that heat treatment can lead to a grain refinement due to a strong fragmentation of elongated grains while only little coarsening in the transverse direction occurs. A smoothing of the gradients in the UFG microstructure as well as in the mechanical properties is observed.