本文报道了钨的含量对12％Cr-W-V-Nb耐热钢高温及室温力学性能的影响。试验结果表明:当钨的含量在2.2—3.0wt-％之间变化时,室温抗拉性能没有明显变化,但冲击韧性却随着钨量的增加而下降。另一方面,钨量的增加提高了短时间的持久强度,但对长时间的持久强度却没有改善作用。钨量的增加对析出行为有两方面的作用:促进Fe_2W型Laves相的形成并增加析出相总量;加速了回火后在高温加热过程中析出相的粗化。钨对高温力学性能的影响与析出特性有密切关系。在持久寿命较短时,析出相来不及粗化,析出量的增加造成了析出强化效果的加强,即钨量的增加提高了高温强度;而当长时间加热后,析出相发生了明显的粗化,降低了析出强化效果。
The effect of W content on the mechanical properties at elevated and room temperatures of 12%Cr-W-V-Nb heat resistant steel has been studied. The room temperature tensile properties vary no more with the W content ranged 2.2--3.0 wt%, while the impact toughness decreases continuously with the increase of W content. Increase in W content made the increase of short-term creep rupture strength,but no improvement over long-term one. The effect of increasing W content on the precipitation behaviour is revealed not only to promote formation of Laves phase Fe_2 W and increase of total amount of precipitates, but also to accelerated the coarsening of precipitate after annealed on high temperature reheating. When the precipitate is not yet coarsened as shorter in rupture life, the precipitation hardening effect may be intensified by the increasing of precipitate, so that the high temperature strength may be raised by the increase of W content, while the precipitate may coarsen markedly and the precipitation hardening effect may reduce on heating for sufficient long time.
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