Ultrafine ferrite in low carbon steel
Ultrafine ferrite in low carbon steel
复制标题
DOI：
10.1016/s1359-6462(98)00411-4
复制
发表时间：
1999-04
影响因子：
6
通讯作者：
P.D Hodgson;M. Hickson;R.K Gibbs
中科院分区：
文献类型：
--
作者：
P.D Hodgson;M. Hickson;R.K Gibbs
钢发展的关键目标之一是细化铁素体晶粒尺寸，因为这导致强度和韧性的增加。铁素体晶粒尺寸的最佳减小通常通过重控制轧制和加速冷却相结合来实现。对于一种简单的钢板轧制钢，该方法可使铁素体晶粒尺寸从热轧和空冷时的10μm减小到控制轧制和水冷时的5μm，使屈服强度提高约80 MPa。在以往有关控制轧制钢的奥氏体向铁素体转变的研究中表明，无论引入奥氏体[1]的残余应变水平如何，铁素体的极限晶粒尺寸约为5μm。这至少部分是由于铁素体在相变b[2]过程中粗化所致。然而，如果能够产生并保留1μm晶粒尺寸（这里称为超细铁氧体（UFF）），那么与5μm铁氧体相比，这将使屈服强度提高近350 MPa。同时，也有一些证据表明，应变诱导转化(即。变形过程中的相变（而不是变形后的相变）会导致显著的铁素体细化[3,4]。Yada和同事声称，通过在接近转变温度的温度下轧制，他们生产出了铁素体晶粒尺寸接近1μm的热轧带钢卷[5,6]，并提出这种细化是通过应变诱导铁素体和铁素体动态再结晶的结合实现的。目前的一位作者也在实验室热扭转测试[7]中产生了均匀的1μm铁氧体微观结构，尽管是在极端变形和冷却条件下。
One of the key goals in the development of steels has been to refine the ferrite grain size, as this leads to an increase in both strength and toughness. The optimum reduction in ferrite grain size is generally achieved through heavy controlled rolling combined with accelerated cooling. For a simple steel composition in plate rolling this can reduce the ferrite grain size from 10μm for hot rolling and air cooling to 5μm for controlled rolling and water cooling, increasing the yield strength by about 80 MPa. In previous studies related to the austenite to ferrite transformation of controlled rolled steels it was shown that there is a limiting ferrite grain size of approximately 5μm regardless of the level of retained strain introduced into the austenite [1]. This is at least partly due to ferrite coarsening during transformation [2]. If, however, a 1μm grain size-here called ultrafine ferrite (UFF)-could be produced and retained then this would increase the yield strength by almost 350 MPa compared to a 5μm ferrite.At the same time there has been some evidence that strain induced transformation (ie. transformation during rather than after deformation) could lead to significant ferrite refinement [3, 4]. Yada and co-workers claim to have produced coils of hot rolled strip where the ferrite grain size approached 1μm by rolling close to the transformation temperature [5, 6], and suggested that this refinement was through a combination of strain induced ferrite and dynamic recrystallisation of the ferrite. One of the current authors has also produced uniform 1μm ferrite microstructures in laboratory hot torsion tests [7], albeit under extreme deformation and cooling conditions.