Fe--36 Ni因瓦合金的热塑性

采用Gleeble-3800热模拟试验机研究Fe-36Ni合金在900~1200℃的热塑性行为，并用FactSage软件、扫描电镜及透射电镜等研究该合金热塑性的影响因素及作用机理.结果表明：合金中主要形成Al2 O3+Ti3 O5+MnS复合夹杂，夹杂物颗粒尺寸集中分布在0.5μm以下.合金热塑性在900~1050℃受晶界滑移及动态再结晶共同影响.晶界上分布的纳米级别(<200 nm)夹杂物有效钉扎晶界，抑制动态再结晶发生的同时减小晶界结合力.微米级别(>200 nm)夹杂物则促进显微裂纹在晶界滑移过程中的形成和扩展，损害合金热塑性.当温度高于1050℃时，较高的变形温度使再结晶驱动力大于钉扎作用力，合金发生动态再结晶，有效提高热塑性.在1100~1200℃区间内，枝晶间裂纹的形成、晶界滑移的加剧及动态再结晶晶粒尺寸增大都降低合金热塑性.

Hot ductility of Fe--36 Ni invar alloy

The hot ductility behaviors of Fe-36Ni alloy in the temperature range of 900-1200 ℃ were investigated by using a Gleeble-3800 thermal simulator. The influence factors and mechanism of action on the hot ductility were systematically analyzed by FactSage software, scanning electron microscopy and transmission electron microscopy. The results show that inclusions in the investi-gated alloy are mainly Al2 O3 +Ti3 O5 +MnS, and most inclusion sizes are below 0. 5μm. The hot ductility of the alloy in the tempera-ture range of 900-1050℃ is influenced by grain boundary sliding and dynamic recrystallization. Nano-scale size ( <200 nm) inclu-sions at grain boundaries effectively inhibit the occurrence of dynamic recrystallization as a result of the pinning effect and decrease the grain boundary cohesion. Moreover, micro-scale size ( >200 nm) inclusions at grain boundaries promote the nucleation and propaga-tion of cracks during grain boundary sliding and decrease the hot ductility of the alloy. Increasing the temperature makes the driving force for dynamic recrystallization larger than the pinning effect, and thus increases the hot ductility significantly by the occurrence of dynamic recrystallization when the temperature exceeds 1050℃. In the temperature range of 1100-1200℃, the formation of interden-dritic cracks, the coarsening of recrystallized grains and the enhanced grain boundary sliding deteriorate the hot ductility of the alloy.