Effect Of Nb、P、Re Content On Mechanical Property Of Weathering Steel

In this paper,the history and the development trend of weathering steel in domestic andinternational industry are summarized. And introduced the micro strengthening mechanismand the main alloy elements of the weathering steel. Baiyunebo iron mine in Baotou isconsidered as niobium and phosphorus symbiotic type iron ore. So the study of how differentNb and P works on weathering steel,so it is very important that we can reasonably use of Nb,Re or other resources.Metallurgical microscope and scanning electron microscope are used to observe themicrostructure and impact fracture caused by different rate of Nb and different rate of P.Combined with the yield strength, tensile strength and impact toughness and other mechanicalproperties to study the effect of Nb and Re on property of weathering steel.The conclusion was summarized as follows:When the P content is constant, with the increase of niobium content, the grain sizedecreases, for the reason of the grain refinement the yield strength and tensile is rising.Longitudinal impact energy at room temperature and low temperature was obviouslyimproved, when niobium content is0.042%, the strength and the toughness reaches the bestvalue; continue to increase of niobium content, pearlite quantity and the grain size increasedstrength hardly changed, and the toughness decreased.When Nb content is basically unchanged,with the increase of the concentration of P, thegrain size decreases, when the content of P is0.093%, yield strength and tensile strengthreached the maximum but the toughness decreased significantly, the impact toughness reachesthe minimum value; continue increasing P content to0.153%, the strength of the trial steel,strength is hardly changed, but the toughness decreased.When adding trace rare earth elements in steel, steel structures in the shape of the acicularferrite and polygonal ferrite, and the grain size became finer, pearlite volume fraction increased, yield strength and tensile strength increases,20℃Akv is157.3J and the impact toughness isimproved.