High Resistance Porous Pieces Obtained by PM, Reinforced with Metallic Yarns

摘要

The paper presents the results of the experiment in the fields of new technologies of obtaining PM reinforced with metallic yarns pieces. This type of high resistance porous pieces are made from a base part from recovered low alloyed steel or iron powder reinforced in the border zone with high alloyed steel yarns. For the reinforcing have been used solid yarns Φ 0,3 mm and mixed yarns Φ 0,45 mm. There have been obtained parallelipipedic samples reinforced with four yarns placed as in fig. 1.1. The samples have been pressed at 300-600 MPa pressure. The pressing has been made orthogonal onto the placement direction of the yarns. The compacting has been made in an unidirectional compression mould with section of 7×51mm. The sintering was made at 1200 degree Celsius in an argon medium. The sintered samples have densities of 5,72g/cm3 (pressed at 300MPa) and 6,72 g/cm3 (pressed at 600MPa). There have been made mechanical bending tests. There were obtained bending strengths σi=490...800 MPa. From the things previously presented it can be observed that this type of reinforced with yarns pieces have high bending strength, though they have high porosity (low density).