CHOOSEN PROPERTIES OF LAYER COMPOSITES OBTAINED FROM ALUMINIUM AND IRON POWDER BY HOT CLOSED-DIE FORGING
Stefan Szczepanik, Marek Wojtaszek, Piotr Nikiel
Quarterly No. 4, 2010 pages 385-391
DOI:
keywords: multi-layer composites, powder metallurgy, aluminum powder, iron powder, hot closed-die forging, mechanical properties
abstract The aim of the research in this paper is to determine the influence of hot deformation of the layer preforms obtained from a mixture of iron and aluminium powders as well as the influence of layers geometry of hot consolidated layer composite samples on the density and some mechanical properties of these materials. The properties of materials after closed-die forging performs, obtained from mixtures of aluminum and iron powder using flat or shape punches are presented. Chemical composition of layers, their position in performs and forming method were investigated to evaluate properties of products. The position of layers in initial preforms were symmetrical and asymmetrical. Cold pressed layer performs were hot consolidated by close-die forging at 485oC, in quasi-isothermal conditions. Influence of the chemical composition of layers, their position during bend and compression tests were investigated. Bend strengths of composite samples were in the range 197 to 230 MPa for specimens with symmetrical position of layers and 144 to 233 MPa for specimens with asymmetrical position of layers, depending on chemical composition and layer geometry and loading by test. Bend strengths of layer specimens taking from webs of shape forgings were 222÷231 MPa for symmetrical layer structure and 182÷271 MPa for asymmetrical layer structure. The higher compression stress 260 MPa were for layer specimens with layer structure B-C-B. Additionally, some information about condition of contact surfaces between components give macrostructure observations. Distribution of components on cross-section, calculated using program Larstran Shape confirm qualitative macrostructure results observation and material flow during shapping. These data can contribute to design of layer materials for specific applications utilising the PM route and closed-die forming. The knowledge of specimen properties, as a function of the layers arrangement allows for choice the most favourable variant to design required properties of the product.