Nanoscale spheroidized cementite induced ultrahigh strength-ductility combination in innovatively processed ultrafine-grained low alloy medium-carbon steel.
Nanoscale spheroidized cementite induced ultrahigh strength-ductility combination in innovatively processed ultrafine-grained low alloy medium-carbon steel.
复制标题
纳米级球化渗碳体在创新加工的超细晶粒低合金中碳钢中诱导超高强度-延展性组合
DOI：
10.1038/s41598-017-02920-9
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发表时间：
2017-06-02
影响因子：
4.6
通讯作者：
Misra RDK
中科院分区：
文献类型：
--
作者：
Jia N;Shen YF;Liang JW;Feng XW;Wang HB;Misra RDK
介绍了在超细晶(UFG)铁素体钢中制备由纳米球状渗碳体(Fe3C)组成的双重组织的低合金中碳钢的新工艺。经多道次轧制和30 0 °C间歇退火后，得到的 -1钢的平均铁素体晶粒尺寸为~430 nm，其中含有平均尺寸为~70 nm的纳米球状渗碳体(Fe3C)。经600 °C、300 S处理后，铁素体平均尺寸增加到680 nm，球化的Fe3C平均尺寸增加到90 nm，称为UFG-2钢。拉伸试验表明，UFG-1钢的屈服强度(σy)为1260 Mpa，极限拉伸强度(σUTS)为1400 Mpa。这些值高于UFG-2钢(σy= 1080 Mpa和σUTS= 1200 Mpa)，表明强化贡献是铁素体晶粒度和纳米渗碳体尺寸减小的累积效应。纳米颗粒与基体之间的非共格界面对位错运动起到了很强的阻挡作用。研究强调，纳米析出物不仅提供强度，而且有助于延展性，这对于提高中碳钢的延性是非常令人鼓舞的。
We describe here innovative processing of low alloy medium-carbon steel with a duplex microstructure composed of nanoscale spheroidized cementite (Fe3C) in an ultrafine-grained (UFG) ferritic steel. After multi-pass rolling and intermittent annealing at 550 °C for 300 s, the obtained UFG-1 steel showed an average ferrite grain size of ~430 nm, containing nanoscale spheroidized cementite (Fe3C) particles with an average size of ~70 nm. On annealing at 600 °C for 300 s, the average size of ferritic grains was increased to ~680 nm and the average size of spheroidized Fe3C particles increased to ~90 nm, referred as UFG-2 steel. Tensile tests indicated that UFG-1 steel had high yield strength (σy) of 1260 MPa, and ultimate tensile strength (σUTS) of 1400 MPa. These values are higher than that of UFG-2 steel (σy= 1080 MPa andσUTS= 1200 MPa), suggesting that the strengthening contribution is a cumulative effect of decrease in ferrite grain size and nanoscale cementite. The incoherent interfaces between nanosized particles and the matrix acted as a strong barrier to dislocation motion. The study underscores that nanosized precipitates not only provide strength but also contribute to ductility, which is very encouraging for improving the ductility of medium-carbon steels.