The Research Of Powder/tube Composite Bar Molding Process

Porous metal materials are novel low-weight materials with extremely low densities and unique combination of excellent mechanical, in respect of energy saving and weight have huge potential application in oil fields. And the quality of the sucker rod directly affects the efficiency of the pumping unit. At present, is one of the most common causes failure of the sucker rod is breaking under load and its weight. So the research of powder/tube porous composite materials have practical guiding significance to the further development of sucker rod.In this paper, metal powder and pore-forming agent are mixing into the blender, then constituting composite billet with sheath. Though high heat sintering and hot extrusion prepare powder/tube composite bar whose core material porosity up to 50%, finally the pore-forming agent and process parameters on the influence law of pore characteristics and performance are studied.Though the testing method of image processing software(Image-Pro Plus), metallographic microscope and compression experiment have analyzed the different structure parameters and mechanical properties of porous core material. Results show that the macro porosity, micro porosity and total porosity of porous core material are from 40.4% to 63.5%, 40.4%-19.6% and 49.9%-19.6%, respectively. The macro aperture changes between 0.60 mm and 1.53 mm, compression strength changes between 15.38 MPa to 127.9 MPa.By orthogonal test method, chrome content, particle size and carbon content on the properties of porous core materials are studied. The compression strength of porous core materials was in the range of 85.32-155.04 MPa. Porous core materials with range analysis and variance analysis show that the influence of parameters on the compression strength are significantly, the influence order of decreasing is carbon powder content, chrome powder particle size and chrome powder content.Different extrusion ratio on interface combination and mechanical properties of powder/tube composite materials are studied. The weight loss rate and the yield strength of powder/tube composite bar specimen in range of 41.9%-47.8% and 210.4-275.9 MPa, respectively. The yield strength present the change trend of increase with the increase of extrusion ratio.