Effect of tungsten on the microstructure evolution and mechanical properties of yttrium modified HP40Nb alloy

This paper investigates the effect of tungsten on the microstructure evolution and mechanical properties of yttrium modified HP40Nb heat-resistance steel. The results demonstrate that, under the casting condition, tungsten addition refines the austenite grain and accelerates the carbide transformation from Cr7C3 into Cr23C6. In addition, tungsten reduces the solid solubility of carbon in austenite grain, and thus inhibits the carbide precipitation during aging at 900 °C. Besides, tungsten suspends the phase transformation of NbC. As a result, the fracture resistance is improved on the tungsten-adopted alloy.