The suitability of high-strength ultrafine and nanocrystalline materials processed by severe plastic deformation methods and aimed to be used for structural applications will strongly depend on their resistance against crack growth. In this contribution some general available findings on the damage tolerance of this material class will be summarized. Particularly, the occurrence of a pronounced...

Ultrafine-grained (UFG) metallic materials processed by severe plastic deformation (SPD) techniques often exhibit significantly higher strengths than those calculated the well-known Hall-Petch equation. These result from fact that SPD processing not only forms UFG structure but also leads to formation of other nanostructural features, including dislocation substructures, nanotwins and nanosized...

A nano/ultrafine grained immiscible Fe-Cu alloy was produced using selective laser melting (SLM) with an average grain size of 250?nm and many 50–100?nm, the finest ever achieved additive man...

This paper presents an overview of fundamentals and potential applications ultrafine-grained Al-based conductors developed with the help severe plastic deformation (SPD) techniques. Based on deliberate formation nanoscale features (such as nanoprecipitates, segregation solutes along crystallographic defects so on) within ultrafine grains, it is possible to optimise their mechanical functional p...

Low-temperature friction-stir welding (FSW) was successfully applied for the joining of Al-Mg-Mn alloy with an ultrafine-grained microstructure. The low-temperature conditions preserved fine-grained microstructure and nano-scale second-phase particles in stir zone thus provided nearly-100% joint efficiency produced welds. deformation behavior welded joints studied via digital image correlation ...

It is well known that when coarse-grained metals undergo severe plastic deformation to be transformed into nano-grained metals, their ductility is reduced. However, there are no ductile fracture criteria developed based on grain refinement. In this paper, we propose a new relationship between ductile fracture and grain refinement during deformation, considering factors besides void nucleation a...

A generalized phase transformation kinetics model is used to understand the martensite to austenite transformation in a cold-rolled and annealed metastable AISI 301LN ultrafine-grained austenitic stainless steel. The model shows that the presence of interstitial nitrogen and heavy cold-rolling is important to promote fast transformation kinetics, through rapid nitrogen-diffusion and austenite n...

Mechanism of fatigue crack initiation was investigated in ultrafine-grained (UFG) magnesium alloy AZ91 processed by equal channel angular pressing (ECAP). Fatigue behaviour of UFG material was compared to the behaviour of material in an initial as-cast state. Focused ion beam technique (FIB) was applied to reveal the surface relief and early fatigue cracks. Two substantially different mechanism...

An ultrafine grained dual phase (UFG DP) steel containing niobium was produced by a new route utilizing simple cold-rolling and subsequent intercritical annealing of ferrite/martensite duplex starting structures. The effects of intercritical holding time on the microstructural evolutions and mechanical properties were studied. The results showed that increasing intercritical holding time enhnac...