粉末挤压成形技术是制备大长径比钨基高比重合金棒材最有效的方法之一,而脱脂过程直接影响着样件缺陷控制及合金力学性能的改善效果.探讨了Φ12 mm和Φ15 mm钨基合金正挤压棒坯溶剂脱脂缺陷的形成及其控制,采用可控恒温仪调控溶剂脱脂速率,利用数码相机和扫描电镜分别对棒坯表面形貌和微观结构进行观察.结果表明：钨基合金正挤压棒坯内存在较大的残余应力,是棒坯溶剂脱脂开裂的主要因素;经退火处理（退火温度为40℃）,正挤压棒坯残余应力得以消除,避免了溶剂脱脂过程中棒坯开裂;经40℃退火和30℃、12 h的溶剂脱脂工艺,可以得到组织均匀分布、无缺陷的脱脂棒坯,且Φ12 mm和Φ15 mm棒坯的脱脂量分别可达40%和30%.
Power Extrusion Molding（PEM） is one of the most effective way to fabricate tungsten heavy alloy rod with large aspect ratio.The debinding process affects the defect control of sample and the improvemnet of mechanical properties of alloy.In this paper,the formation and control of defects in forward extrusion rods（Φ12 mm and Φ15 mm） during solvent debinding process were discussed.Constant temperature controlling device was used to control solvent debinding rate,the surface and the microstructure of extrusion rods were observed by digital camera and Scanning Electron Microscope（SEM）,respectively.The results showed that there was big residual stress in tungsten-based alloy extrusion rods,which was the major factor leading to the cracking of green rods extruded during solvent debinding process.The residual stress of the green rods could be relieved by an annealing process（at 40 ℃ annealing temperature）,and it could effectively avoid the cracks.Under annealing at 40 ℃ and solvent debinding at 30 ℃ for 12 h,the rods structures were uniform with no defects,and the debinding efficiency levels of Φ12 mm and Φ15 mm could reach 40% and 30% respectively.
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