Study And Development On Ultra-Fine Grain And Corrosion Resistant Steel

In this experiment powerful carbonitride element titanium has been added to the 0Cr13 ferritic stainless steel, 0Cr13 ferritic stainless trial steel with titanium has been fabricated by general smelting and rolling process. Titanium's influence on the strength and toughness of trial steel has been explored; The characters of microstructure ,precipitation particle and grain boundary of the trial steel have been analysed ; Corrosion resistant of the trial steel has been also studied in this article. When material is deformed under below austenite recrystallization temperature and above Ar3 phase transition temperature, phase transition can be occurred, and smaller radius critical crystal nucleus can be obtained. To obtain ultra-fine ferrite grain, heavy deform must be applied to the steel material. Titanium can impede austenite grain's growth by carbonitride of titanium at soak temperature; It can impede austenite recrystallization in hot rolling process; In addition, very small and undissolve carbonitride particles also can promote phase transition. These elements make ulta-fine grain ferrite be possible. Titanium can refine 0Cr13 ferritic stainless steel, increase its strength , improve its ductility so that it has good mechanical working properties. The amount of additive titanium has a best range, excess or lack titanium do not play best strengthening and toughening role. Analysis and computation shows that the second-phase precipitation particles Ti(C,N)dragging ferrite grain boundary depends on particles' magnitude and volume fraction; More smaller Ti(C,N)particles and more volume fraction, more fine ferrite grain and better mechanical properties. Kinetics and thermodynamics analysis shows that smaller precipitation particles are easy to coarsen, so that it is difficult to obtain quite fine the second-phase precipitation particles.The experiment shows that 0Cr13 ferritic stainless steel is lack in intercrystalline corrosion resistant. After titanium is added to the steel, titanium and carbon can format stable combination so that (Fe,Cr)23C6 on the grain boundary is depressed . Additive titanium erases carbon andnitrogen gap atoms, perlite structure is canceled so that ferrite grain boundary is purified, ferrite structure is homogenous so that corrosion resisting property is heightened.