Correlation between Microstructure/Fracture Surfaces and Material Properties

Abstract

The present paper deals with the evaluation of the eect of dierent vacuum heat treatments on the microstructure and fracture surfaces of a low alloyed sintered Fe[1.5Cr0.2Mo]0.6C steel, in correlation with the mechanical and plastic properties achieved. The heat treatment consists of the sintering process in vacuum furnace at 1393 K for 1800 s, followed by dierent cooling conditions and an integrated nal tempering at 473 K for 3600 s. The average cooling rates, calculated in the range of 1393 K to 673 K, were 0.1, 0.235, 3, and 6 K/s, respectively. Vacuum heat treatment is supporting the bainitic-martensitic microstructure, the higher the faster cooling rate applied. This provides a marked increase in strength coupled to a decrease in ductility. The decrease of the impact energy after heat treatment is justied by the microstructural changes, especially if a part of bainite is converted to brittle martensite. Samples with bainitic microstructure presented higher impact energies than those with martensitic microstructure. This is fully conrmed by the fracture surface analysis at higher magnication, revealing three main micromechanisms of fracture: brittle, ductile and quasi-cleavage.

Microstructural and mechanical characterization of additively manufactured parts of maraging 18Ni300M steel with water and gas atomized powders feedstock

“…These oxides exhibit microcracks likely nucleated and propagated due to their high fragility, which partially explains the previously discussed tensile results. Similar findings regarding protuberances, cracks, ridges, and oxide decohesion on the fracture surfaces of maraging steels and Fe-Cr-Mo and Fe-Cr-Y alloys were reported in the studies referenced by [36,50,61,62].…”

Determination of ductile fracture criteria for bulk and PM materials

“…Moreover, porosity has a significant influence on the stress distribution. As the stress is inhomogeneously distributed across the sample it can lead to reduction of the effective load bearing area [30][31][32][33]. The nCL critical value for HSLA was calculated 0.38-0.4, it was compared to that for AISI 1040 carbon steel with similar chemical composition.…”

Microstructure, Strength, and Fracture Topography Relations in AISI 316L Stainless Steel, as Seen through a Fractal Approach and the Hall-Petch Law

“…In metallic polycrystalline alloys, the relation between the fracture surface features and the underlying microstructure is very well known [14][15][16]. As the mechanical properties depend on the microstructure, it is clear that the topography of the fractured surfaces is also related to the mechanical properties.…”