Analysis of contact conditions and microstructure evolution in shear assisted processing and extrusion using smoothed particle hydrodynamics method. (September 2022)

• Record Type: Journal Article
• Authors: Li, Lei; Reza-E-Rabby, Md; Overman, Nicole; Wang, Tianhao; Whalen, Scott; Grant, Glenn; Mathaudhu, Suveen; Soulami, Ayoub
• Is Part Of: Materials & design. Volume 221(2022)
• Publication Date: 2022-09
• Subjects: Shear assisted processing and extrusion (ShAPE) -- Smoothed particle hydrodynamics -- Aluminum alloy 7075 -- Stick-slip contact condition -- Heat generation rate; Materials -- Periodicals; Engineering design -- Periodicals; Matériaux -- Périodiques; Conception technique -- Périodiques; Electronic journals; 620.11
• DOI: 10.1016/j.matdes.2022.111010
• Languages: English
• ISSNs: 0264-1275

Abstract

Graphical abstract: Highlights: A meshfree model is developed for shear assisted processing and extrusion of 7075 Al with experimental validations. Simulation results reveal the full-sticking condition dominates the tool-billet contact interfaces in the steady state. Around 80% of the steady-state heat generation is attributed to plastic dissipation work from material deformation. Lower extrusion temperature favors smaller grain size and potentially superior tensile properties in the extruded tubes. Abstract: Shear assisted processing and extrusion (ShAPE) is a solid-phase processing technique that adds an additional shear force as compared with a conventional extrusion approach. Recently, ShAPE has demonstrated the capability of extruding high-performance aluminum alloy 7075 (AA7075) tubes at speeds up to 12.2 m/min without surface tearing. However, the relationship among the ShAPE processing parameters, thermomechanical conditions, contact conditions, heat generation, and microstructure evolution remains primarily empirical because an insightful understanding of the associated physics is still lacking. To help elucidate these relationships, this work proposes a thermomechanical meshfree model for the first time for ShAPE processing of AA7075 using the smoothed particle hydrodynamics (SPH) method. The meshfree model is first validated thoroughly by experimental data in terms of material flow, die face temperature, and extrusion force with various processing parameters. The validated model is then used to analyze the steady-state contact conditions and heat generation rates during ShAPE processing. Distributions of the average grain size of AA7075 being extruded are calculated using the SPH model output. The meshfree model results reveal that extrusions conducted at lower temperatures and higher strain rates yield more refined grains and possibly higher material strength, which is also consistent with the experimental observations.