Application of small specimen testing technique for mechanical property assessment of discontinuously reinforced composites

Abstract

The shear punch experiment is a small specimen testing technique that has been used to assess the flow properties, such as strength and ductility, of traditional engineering alloys when material availability is limited. In the present study, the applicability of a laboratory shear punch testing system, which was fabricated to evaluate the mechanical properties of different materials (steels, aluminium alloys, copper alloys, titanium alloys and cobalt alloys), was extended to include tensile mechanical property assessment of discontinuously reinforced metal matrix composites. In employing this testing technique to discontinuously reinforced composites, the shear punch loaddisplacement data were examined to identify the critical regions of the flow curve, i.e. elasticity followed by yielding, work hardening, ultimate tensile strength and fracture. The loaddisplacement curves and the fracture characteristics generated by shear punch testing were then compared with the conventional tensile data and failure behaviour in order to calibrate the method for composite materials. It was determined that the flow characteristics from shear punch testing can be used to predict the mechanical properties of discontinuously reinforced metal matrix composites through linear correlations for the yield strength, ultimate tensile strength and percent elongation.

Mechanical Properties of Gd‐CeO2 Electrolyte for SOFC Prepared by Aqueous Tape Casting

“…On the other hand, localized mechanical testing techniques which can provide the mechanical characteristics from small specimens have generated much interest in recent years. SPT as one of the well-known examples of these miniature mechanical testing methods has been applied to a wide range of materials such as metals and alloys [34], composites [35,36], and biomaterials [37]. This test is based on a blanking operation in which a flat cylindrical punch shears a disk specimen with the thickness usually in the range of a few hundred microns and the diameter more than 5 mm clamped between two die halves at constant speed [38,39].…”

Application of Shear Punch Testing to Study Microstructure-Property Relationships in Electron Beam Welded 17-4 PH Stainless Steel

“…where n s and n t are the work hardening exponents in SPT and tensile and C n is the correlation coefficient for the work hardening rate, which was determined in previous work to be 1.1 for a range of materials [4].…”

“…Thus use of SPT has been considered during optimization of thermomechanical processing schedules for steel through evaluation of laboratory sized cylindrical specimens (11 mm in height by 7 mm in diameter) for microstructural changes and the resulting tensile properties [3]. For metal matrix composites produced by casting or powder metallurgy processing, the adaptation of SPT has been also reported to permit a convenient means of evaluating the flow properties with relative simplicity (specimen geometry, test set-up and alignment) and inexpensiveness (small sampling volume and straightforward machining), as compared to conventional tensile testing [4]. Some work has also commenced on configuring SPT for examining the mechanical property gradients associated with microstructural changes in the fusion zone (FZ) and HAZ of welded structures, including ferritic 2.25Cr-1Mo steel [5] and 4130 steel [6], to provide insight on the yield and facture behaviour.…”

“…yield and maximum strength, ductility and work hardening exponent). These attributes have contributed to the recent popularity of SPT for examining the interrelationship between processing conditions, microstructure and mechanical properties from a small specimen volume [2][3][4]. Thus use of SPT has been considered during optimization of thermomechanical processing schedules for steel through evaluation of laboratory sized cylindrical specimens (11 mm in height by 7 mm in diameter) for microstructural changes and the resulting tensile properties [3].…”

“…Yet, the application of SPT for assessing the mechanical property gradients can present significant advantages over microhardness testing. First, the sampling volume of 2 × 10 -2 mm 3 (1.5 mm diameter punch and 25 µm punch-die clearance) in SPT is considerably greater than the plastic zone of about 4 × 10 -4 mm 3 in hardness testing, which permits the measurement of 'bulk' mechanical property data with contributions from multiphase constituents within the area of interest [4]. Secondly, the instrumented SPT provides punch loaddisplacement data, which has been shown to exhibit similar features to that observed during blanking of metallic materials with the presence of 1) an elastic phase region, 2) a plastic deformation region with strain hardening, 3) a maximum punch force, 4) a plastic deformation region under a decreasing shear area and 5) a final fracture region [10].…”