Refining a metal’s grain size can result in dramatic increases in strength, and the magnitude of this strengthening increment can be estimated using the Hall–Petch equation. Since the Hall–Petch equation was proposed, there have been many experimental studies supporting its applicability to pure metals, intermetallics and multi-phase alloys. In this article, we gather the grain-size strengthening data from the Hall–Petch studies on pure metals and use this aggregated data to calculate best estimates of these metals’ Hall–Petch parameters. We also use this aggregated data to re-evaluate the various models developed to physically support the Hall–Petch scaling.

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Six decades of the Hall–Petch effect – a survey of grain-size strengthening studies on pure metals

Hall-Petch relationship in Mg alloys: A review

Mechanistic investigation of a low-alloy Mg–Ca-based extrusion alloy with high strength–ductility synergy

The mechanism for the high dependence of the Hall-Petch slope for twinning/slip on texture in Mg alloys

Additive manufacturing of biodegradable metals: Current research status and future perspectives.

Influence of texture on Hall–Petch relationships in an Mg alloy

Prepreg tack is a critical material property that plays a key role in Automated Fibre Placement (AFP) manufacture-induced defect generation. However, there is a gap in current state-of-the-art manufacturing process modelling that includes tack phenomena and experimental data that shows the influence of multiple factors. In this paper, a modified probe test method, which is capable of inter-ply and ply-tool tack measurement, is proposed. The influence of multiple factors, consistent with the AFP deposition process (i.e. pull-off rate, contact time, pressure and temperature) on tack is studied. Further, a comprehensive modelling framework accounting for all the factors is developed and implemented as a user subroutine for a commercial finite element (FE) package. The work highlights the complexity of tack behaviour at play and shows promise for filling the gap between the tack data/model scarcity and simulation of manufacturing processes such as AFP and forming. 

Yi Wang

Papers

Influence of texture on Hall–Petch relationships in an Mg alloy

Understanding tack behaviour during prepreg-based composites’ processing

Modelling the Effect of Process Conditions on Steering-Induced Defects in Automated Fibre Placement (AFP)