The dynamic continuous cooling transformation（CCT）diagram and phase transformation rules of 510 MPa automobile beam steel,which is produced by a continuous casting of thin slab of FTSR technology in Tangshan Iron and Steel Co.Ltd.,are researched by thermal simulation experiment.The microstructure characteristics of the beam steel under different test conditions are studied by means of optical microscope and scanning electron microscope.The test results show that the critical temperatures of phase transformation Ar3 and Ar1 will all decrease with the increase of the cooling rate.When the cooling rate is lower than 20 ℃·s-1,the ferrite and pearlite phase transformations are the main parts;when the cooling rate is higher than 20 ℃·s-1,the bainite phase appears.Moreover,the microstructures of 510 MPa automobile beam steel produced by FTSR technology are also studied,and the results are basically in accordance with the CCT diagram gained from the test.
WANG XinKANG Yong-linYU HaoCHEN Li-binKONG Qing-fu
为了研究薄板坯连铸连轧(TSCR-Thin Slab Casting and Rolling)工艺生产条件以及给定化学成分下B对低碳罩式退火钢板织构的影响,对含B和无B退火板进行了X射线织构测试,并对热轧、退火板进行了电解化学相分析.试验结果表明:在AlN含量几乎相等的情况下,退火板中γ纤维织构组分含B钢低于无B钢;含B钢和无B钢热轧、退火板电解溶样均得到包含碳化物、AlN等在内的粉末,含B钢中还有B的化合物.含B钢中细小的AlN、BN及Fe的B、C化物共同作用影响织构的生成与发展,而B主要是通过BN等第二相粒子影响晶粒的变形、生长,进而影响织构发展.因此,AlN不是影响织构发展的唯一决定因素.
