Scientists from the UC3M Powder Technology Group (GTP) used a scanning electron microscope to obtain high-resolution images, combined with on-site characterisation tests, they have been able to understand the behaviour of sintered steels on fracturing. Researchers discovered where the first cracks 'nucleate' and where they particularly extend to.
Several steels currently on the market were evaluated, an Fe-C steel, a steel pre-alloyed with molybdenum, and Distaloy AE, which is iron alloyed by diffusion with copper, nickel and molybdenum. The results have helped in understanding the connection between microstructure and properties; it is not just the phases but also the residual porosity that composes their microstructure.
José Manuel Torralba, full professor in the UC3M department of Materials Science and Engineering, and Deputy Director of the IMDEA Materials Institute, explains: "The research has revealed, among other things, that the most angular and irregular pores are the first points of 'nucleation,' that is, those that initiate the breaking."
This study. . . .makes changes in the microstructure of the material visible while it is being tested, says Torralba. The methodology used is applicable to any type of alloy, he says, not only to test behaviour under pressure, but also behavior at high temperatures.
The study is published in Powder Metallurgy.