Effect of trace Mg addition on microstructure and mechanical properties in 2.25Cr1Mo steel
In order to reveal the function of Mg micro-alloying in low micro-alloyed steel,the 2.25Cr1Mo with 15 mm thick steel plates containing different Mg content were prepared with vacuum induction furnace and rolled with double-stick reversible rolling mill.The characteristics of heat-treated microstructure,primary austenite grain,and mechanical properties were investigated with TEM,OM and so on.The results show that after adding Mg for the heat-treated microstructure,the primary austen-ite grain size is refined and the ferrite volume fraction is increased.When the total oxygen content of 2.25Cr1Mo steel is 0.000 3％,Mg will segregate in the carbides,thereby reducing the size of carbides and increasing the amount of these compounds,which increases the pinning effect on austenite grain growth,and then refines the original austenite grain.After adding 0.005％Mg,the impact toughness of 2.25Cr1Mo steel is slightly improved,but the microhardness change is not obvious.The increase of fer-rite content in steel after Mg treatment contribute to improving its impact toughness.
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