不同合金元素的添加对含Ti微合金高强钢组织性能的影响

Effects of Different Alloying Elements on Microstructure and Properties of Ti-containing Microalloyed High Strength Steel

利用光学显微镜、扫描电镜、透射电镜、能谱分析和拉伸试验等手段,对分别加入Mo、Cr、Nb、Cu等合金元素的含Ti微合金铁素体高强钢组织、析出相和力学性能进行分析,结果表明:铁素体基含Ti微合金高强钢以铁素体为基体,部分微合金钢组织含有极少量粒状贝氏体或珠光体;基体析出粒子尺寸差别较大,大部分尺寸小于10 nm并呈球形、簇状分布,析出物以TiC或(M、Ti)C颗粒为主;5种成分设计的铁素体基含Ti微合金钢均具有良好的室温、高温拉伸性能,550℃拉伸屈服强度均大于380 MPa,为对应室温拉伸屈服强度的63%以上,其中加少量Nb元素的含Ti微合金钢高温和室温屈服强度比最高,达到0.77,具有优异的高温力学性能。

The microstructure,precipitate phase and mechanical properties of Ti-containing microalloying ferrite high strength steel with addition of various alloy elements such as Mo,Cr,Nb and Cu by means of devices and relevant methods including optical microscope(OM),scanning electron microscope(SEM),transmission electron microscope(TEM),energy dispersive spectrometer(EDS)and tensile test.The results show that ferrite based Ti-containing microalloyed high strength steel takes ferrite as matrix,the microstructure of some microalloyed steel contains less granular bainite or pearlite.The size of matrix precipitates particles has great difference,most of the particles has a size less than 10 nm in spherical shape and cluster-like distribution,the precipitate phase mainly consists of TiC or(M,Ti)C particles.All the five ferrite based Ti-containing microalloyed steel in the test possesses good tensile properties at both ambient and high temperature,the yield strength from high temperature tensile test at 550℃is over 370 MPa,which is more than 63%of corresponding yield strength from tensile test at ambient temperature.The Ti-containing microalloyed steel with less Nb addition has highest ratio of high temperature yield strength to ambient temperture yield strength,which is 0.77,and also possesses excellent high temperature mechanical properties.