Mechanism of fracture of aluminum blanks subjected to stretching along the sheared edge

Abstract

The objective of this study was to investigate the mechanisms of fracture of aluminum blanks subjected to shearing and stretching along the sheared edge. In this study, a new imaging technique was implemented to track the stretching of the sheared edge until fracture. A 1 mm square grid was etched onto the sheared samples and a video of the sheared surface was taken incrementally during tensile test of the sample. The influence of cutting clearance in the trimming operation on sheared edge stretchability and mechanism of fracture of sheared surface during its stretching were investigated. Excessive plastic deformation of the burr area during the trimming operation was identified as a major factor leading to early fracture initiation from the tip of the burr. Deburring or solution heat treatment of samples trimmed with excessive clearance may increase stretchability to the level observed for the samples trimmed with accurate alignment of the tools. Roughening of the sheared surface produced with 5% cutting clearance did not have any significant effect on elongation of the sheared edge. Trimming process with scarp support eliminated burrs on the sheared edge for a large range of cutting clearances and substantially improved sheared edge stretchability.

Slanted Blades Optimizing Grain Texture and Work Hardening of Non‐Oriented Electrical Steel in Stress Coverages during Shearing and Blanking Processes

“…All dimple fractures, protuberances, and scratches were common on the cut sections, and their proportion would change according to the inclination angle design. Commonly, the edge flanks cut by flat blades contained extra collapse angles and harmful burrs, [16,17] but they were not observed at the edges sheared by slanted blades with inclination angles.…”

Modeling and Experimental Analysis of Shear-Slitting of AA6111-T4 Aluminum Alloy Sheet

“…Analyzing, guillotining, trimming and blanking processes [ 13 , 15 , 16 , 18 ] make it evident, that a bending moment occurs for any horizontal clearance. Contact stresses are distributed along a certain area of the cutting tools’ shearing edges and the cut material.…”

“…Some studies have been conducted to understand the shearing mechanisms of construction steels. The effect of shearing process conditions on sheet deformation, stress variables, fracture mechanisms and sheet defect problems based on guillotining, blanking and trimming processes was examined [ 15 , 16 , 17 , 18 , 19 ]. Analyses and experimental tests of the finite element method (FEM) were carried out aiming at the improvement of the cutting process.…”

“…Nasheralahkami et al [ 21 ], based on advanced high strength steel, studied the effect of clearance and tool wear on trimmed edge formation, and the impact of process parameters on burr defect was investigated. Golovashchenko and Wang [ 16 , 22 ] investigated tensile stretching of aluminum, edge cracking and burr formation problems of material, that had previously been trimmed. In [ 22 ], Golovashchenko presented the results of metal sheared edge stretchability and fracture mechanism during trimming.…”

Analysis of the Influence of Blanking Clearance on the Wear of the Punch, the Change of the Burr Size and the Geometry of the Hook Blanked in the Hardened Steel Sheet

“…He showed that the inclination angle of the sheet can be chosen with a relatively large clearance so that a flat surface of the intersection without burrs will be obtained. The mechanism of separation of materials during shearing can be changed by modifying tool arrangement [28]. In paper [29], the authors presented the results for the DP500 high-strength sheet shearing tests using an additional element supporting the sheet material.…”