Effects Of Trace Elements Cu, S And As In Ti-IF Stee

Owing to its exeellent deep stamping and no aging perofrmances,IF steel beeomes a new generation of stamping steels.Now,the manufacturing of IF steels is in an elementary development stage in China and can meet the quality requirements of trucks and low-grade automobiles.There is much greater disparity in products’ quality between China and foreign counntries.In recent years,a large number of low quality iron ore and scrap are used for reducing costs.Therefore,more and more residual elements exist in IF steels and they have had a significant influence to the performance of steel products,most of which are adverse.So,the studying on the trace elements Cu,S and As in Ti-IF steels has great theoried significance and practical values.In this paper,we studied the ferrite phase transformation and hot rolling process of Ti-IF steel containing trace elements Cu,S and As by thermal simulation test,mechanical and forming properties were studied by tensile test.The recrystallization texture of Ti-IF steels is studied by X-ray diffraction,hot rolled Ti-IF steels’ micro cracks and microstructure were observed by scanning electron microscope.The results of the studying on phase transformation behaviors during continuous heating and cooling processes showed as follows.Compared the Ti-IF steel containing trace Cu and As with the Ti-IF containing bare Cu or As,the starting temperature point of austenite transformation during continuous heating and the finishing point of ferrite transformation during continuous cooling were significantly increased by the addition of 0.08%Cu and 0.04%As in the 0.08Cu-0.04As-Ti-IF steel.The results of the studying on mechanical and forming properties showed as follows.The trace elements of Cu,S and As in Ti-IF steels almost has no effect on mechanical properties but they could deteriorate the forming abilities.Additions of 0.04%As or 0.08%Cu+0.04%As in Ti-IF steels cause a significant reduce of r0 and r45,that have adverse effects on the deep drawing abilities.The micro cracks of hot rolled 0.08Cu-0.012S-Ti-IF steels are observed along the grain boundaries and Cu,S are founded.