用喷射成形工艺制备的无宏观偏析、组织为均匀细密珠光体的超高碳钢，无需任何热的或机械的预处理，即可具有伸长率达380%的超塑性，并且在2×10-1s-1的应变速率下仍有122%的伸长率。这是由于在此变形过程中发生了碳化物由片层状向颗粒状的转变并形成细小等轴晶粒的组织超塑化；而且高应变速率可促成高度细化的球化组织。由此开发的喷射成形结合大压下量热轧的方法可以简捷有效地使超高碳钢获得很好的超塑性，并且可以应用于高速钢等其它高碳钢铁材料。
1.25C2.8Si1.5Cr ultrahigh carbon steel (UHCS) with a carbidenetworkfree and fully fine pearlitic microstructure,prepared by spray forming technology, exhibits fairly good superplasticity with elongation up to 380% without any thermal and/or mechanical pretreatment.An elongation of 122% was reached when the strain rate was raised to 2×10-1s-1.It was found that the unique superplasticity is resulted from microstructure evolution during the deformation, from the pearlite to fineequiaxedgrained structure with the lamellar cementite turning into spheroidized particles. High strain rate could facilitate utrafine spheroidized structure. Based on the above result, a method combining sprayforming and hot rolling with highdeformation rate was developed to make UHCS superplastic more effectively. The method was proved to be effective for other highcarbon steels such as highspeed steels.
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