G3镍基耐蚀合金管材热挤压工艺润滑行为研究 Ⅰ.玻璃润滑膜厚度模型建立及应用

RESEACH ON LUBRICATION IN HOT EXTRUSION OF G3 CORROSION RESISTANT Ni-BASED ALLOY TUBE Ⅰ.Establishment and Application of Glass Lubricating Film Thickness Model

研究了G3镍基耐蚀合金管材玻璃润滑热挤压工艺中润滑膜的成膜行为,建立了润滑膜厚度的理论计算模型.同时,针对6000 t卧式挤压机,结合G3合金热挤压工艺有限元模拟分析,对热挤压工艺参数和玻璃润滑剂黏度进行了系统的研究.结果表明,可以通过玻璃润滑膜厚度及完成一次热挤压所需玻璃垫厚度的理论计算公式优化G3合金管材热挤压工艺参数,并进一步获得了玻璃润滑剂黏度性质须满足:玻璃粉的软化温度大约为720℃;在720-800℃,玻璃黏温系数在-0.05℃^(-1)和-0.04℃^(-1)之间;热变形温度1100—1200℃区间的黏度为25—200 Pa.s.

In the hot extrusion of steel,adequate lubrication can be obtained by placing a glass pad made of compacted glass powder in front of the billet.During the extrusion,the glass pad progressively melts in thin layer,allowing lubrication to be maintained over the entire stroke.However,the thickness of glass pad in a single operation is markedly depends on the process parameters and glass properties.Therefore,the mechanism of glass lubrication film forming and film thickness calculation model has been investigated during hot extrusion of G3 nickel-based alloy tube.Furthermore,combined with FEM code,the operation variables and viscosity of glass lubricant have been systematically researched in the hot extrusion of G3 alloy tube which is conducted on the 6000 t horizontal extrusion press.The results showed that the processing parameters can be optimized using the thickness formulation of lubrication film and glass pad during a single press operation.Moreover,under the practically technical parameters of hot extrusion G3 alloy tube,the requirements of glass viscosity are as follows： softening temperature about 720℃;the viscosity coefficient ranges—0.05℃^（-1） to—0.04℃^（-1） when temperature is between 720 and 800℃;the viscosity ranges 25 Pa·s to 200 Pa·s during the hot working temperature 1100—1200℃.