Experimental Study On Near-Net-Shape Forming By Hot Isostatic Pressing Based On Using Laser Melting Technology Forming Homogeneous Can

Near-net-shape using hot isostatic pressing is a new application of hot isostaticpressing. This technology can forming any complex metal parts with fully dense at once. Ithas unique advantage in forming high melting point and complex structure metal materialswhich are difficult to manufacturing by the traditional processing. However, in order tomeet the requirements of near-net-shape, it will make special predeformation cans. Thesecans are complex and hard to machine. Selective laser melting(SLM) technology canmake any complex metal parts, in the condition of no mold and no fixture. It will bepossible to solve the problem that the predeformation cans are hard to machine. And it canbe used to make homogeneous cans to save materials and to avoid the pollution fromheterogeneous cans. But the technology is not very mature in china, and its product is hardto meet the requirement of seal.Therefore, the idea of fission design is proposed. The can is divided into two parts ofcontrolling shape and seal, according to the function. The first part adjoins powders andhas complex shape. It will be made by SLM technology. The second part is in outer andcould be simple. It will be made by the machining process. Such, it can fully use thestrengths of the SLM technology to forming predeformation cans.In order to study the problem of using SLM technology to manufacture homogeneouscans as the shape control parts, two comparative experiments are designed taking316Lstainless steel powder material for example in this thesis. The one have SLMhomogeneous can,and the other one don’t. Firstly, obtain the shape and size of thepredeformation can through simulating and optimizing, so the design of predeformationcan could be completed. According to the principle of adaptation, complete the design ofthe outer machining can. Then, the SLM can is manufactured with optimized SLM processparameters and assembled with machining can for hot isostatic process experiments.Compared the two test pieces on the macro properties(relative density, hardness) andmicrostructure(OM, ESEM). It can be found that the two test pieces have no obviousdifference in forming quality, and the test piece which has homogeneous can made bySLM technology has a better control in shape. So I affirmed that it’s feasible to use SLM technology manufacturing shape controlled can. Compared the test pieces which hashomogeneous can made by SLM technology with itself. It can be found that theuniformity of organization of the SLM can is poorer, and powder density area has moreuniform performance. So using SLM technology to make homogeneous can is moresuitable to the occasion that the microstructure uniformity demand is not high or hasspecial performance requirements on the surface.