Effect of heat treatment on microstructure and mechanical properties of as-cast Fe-Cr-W-B alloy
Fe-W-B alloys have excellent nuclear radiation shielding effect,but poor mechanical properties.The Fe-Cr-W-B alloy powder produced by adding Cr element has relatively fine boride microstructure.In order to further im-prove the microstructure and mechanical properties of Fe-Cr-W-B alloy,this paper investigates the effect of heat treatment at 1200 ℃ for 1 h on the microstructure and mechanical properties of cast Fe-Cr-W-B alloy.The results show that the as-cast Fe-Cr-W-B alloy is composed of α-(Fe,Cr,W)as matrix and M3B2(M=W,Cr,Fe)as boride precipitated phase.The boride is distributed in a continuous network at the grain boundary,which causes stress con-centration in the matrix during deformation,resulting in extremely poor ductility and toughness of Fe-Cr-W-B alloy.After heat treatment at 1200 ℃ for 1h,W atoms in Fe-Cr-W-B alloy matrix enters the boride,solid solution strengthening effect is weakened,reducing the hardness and strength;the boride volume shrinks,the continuous mesh structure at the grain boundary is broken,and the ductility and toughness of Fe-Cr-W-B alloy is improved.
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