变形量对锻造钨棒组织及力学性能的影响

Effect of Deformation on the Microstructure and Mechanical Properties of Forged Tungsten Rod

采用粉末冶金和摔模锻造方法制备大尺寸纯钨棒材,详细研究了不同变形量对锻造钨棒室温、高温组织及力学性能的影响,掌握了钨棒变形过程中组织及性能的演变规律,为高质量锻造钨棒生产提供参考借鉴。结果表明:随着变形量的增加,由于致密化和形变强化、细晶强化等多重因素影响,钨棒室温抗拉强度逐渐增大,密度、硬度等呈先快速上升后逐步平缓的趋势,室温断口由沿晶脆性断裂向沿晶脆性断裂+穿晶解理断裂的混合型方式转变;钨棒高温拉伸具有典型的颈缩现象,其抗拉强度和延伸率总体呈增大趋势,高温韧窝断裂完全转变温度降低,且断口韧窝尺寸相对较大。综合考虑显微组织、力学性能及成品率等因素,建议锻造钨棒变形量应达到60%以上。

Large size tungsten bars were manufactured by powder metallurgy and stamp forging methods.The influence of various deformation amounts on the microstructure and mechanical properties of forged tungsten bars at room and elevated temperature was studied in detail.We have mastered the regularity of microstructure and properties of tungsten bar during deformation,which could provide reference for the production of high-quality forged tungsten rod.The results show that with the increasing of deformation,the tensile strength of tungsten rods increases gradually due to the effect of multiple factors,such as densification,deformation strengthening and fine grain strengthening,etc.The density and hardness of tungsten rods increase rapidly at first and then gradually decrease,the room temperature fracture mode changes from the intergranular brittle fracture to the mix of intergranular brittle fracture and transgranular cleavage fracture.With the increasing of deformation,the tensile strength and elongation of tungsten rods increase basically with the typical phenomenon of necking at high-temperature,the complete transition temperature of dimple fracture decreases,and the dimple size at high-temperature fracture is relatively large.Considering factors such as microstructure,mechanical properties and yield,it is suggested that the deformation of forged tungsten rod should reach more than 60%.