Effect of copper infiltration on fracture mode in sintered steels

Abstract

The fracture mode of PM steels depends on features, such as pores, densification, diffusion of any added alloying elements, contact area between particles, microstructural homogeneity, and applied load conditions. Consequently, when a sintered steel is infiltrated, several factors that determine the fracture behaviour are affected. The density is raised (in absolute terms, because the infiltrant is usually of higher density, and in relative terms, because activated sintering is promoted by permanent liquid phase sintering). The liquid phase promotes a rounding of the pores which enhances stress transmission from the necks to the particles. Sintered steel with 0?6%C was infiltrated with three amounts of copper to study the influences of the amount of infiltration and the resultant final density on the fracture mode. Specimens were first uniaxially pressed to 7?0 g cm 23 green density, then sintered and infiltrated simultaneously at 1120uC in a 90N 2 -10H 2 atmosphere. The mechanical results and microstructures were analysed to evaluate the fracture behaviour and fracture surfaces. The mechanical behaviour was characterised by hardness, tensile and three point bending tests.

A simple and economical method for the synthesis of steel-reinforced copper composite

“…Many attempts have been made to prepare copper- infiltrated metals 11,12 and ceramics 13–15 in order to improve mechanical properties such as machinability and porosity reduction. For example, copper infiltrated iron and steel compacts are widely used in different applications 16 such as: to manufacture high speed steel based composites; 17,18 and as a valve seat insert material.…”

Effects of warm die on high velocity compaction behaviour and mechanical properties of iron based PM alloy

“…8,9 In addition, higher green density results in less shrinkage and distortion during sintering, which means a better dimensional accuracy. 10,11 So, to improve green density is the key to obtain excellent mechanical properties and perfect dimensional accuracy. 12 High velocity compaction (HVC) is an efficient technology for preparing high density PM components.…”

Effect of Cu infiltration on static and dynamic properties of PM steels

“…Infiltration of porous steel parts with Cu is a common process used to improve the overall properties of powder metallurgy (PM) parts. [1][2][3][4][5][6] Infiltration is an economical process to obtain near full density parts compared to thermomechanical processes such as hot isostatic pressing and forging. Commercially Cu has been the infiltrant of choice in PM steels since capillary infiltration is thermodynamically promoted by the small contact angles between liquid Cu and steel.…”

“…11,20 It has been clearly shown, for various PM steels systems, that Cu infiltration increases tensile properties by achieving a high density. [1][2][3][4] However, the influence of Cu infiltration process on the endurance limit of PM steels is not well documented and the few results were inconclusive due to erosion problems. 5 On the other hand, studies made on non-infiltrated parts clearly show that increasing density has a major effect on the endurance limit.…”