An experimental approach for blankholder force determination for DP600 with different material flow strain rates in the flange during stamping

Abstract

Manufacturing efficiency is directly related to the parameters of the process and the material used. In sheet metal industry, the manufacturing process often results in changes in design of the tool to safely stamp the product. These changes in design could occur due to use of a new material with better formability, adjustments to the design of tools and/or the process parameter variation. In order to avoid the trial-and-error procedure, forming limit curve is an effective method for this assessment and is widely used by several authors in recent publications, that is, the use of forming limit curve could be useful to decrease the trial-and-error procedures and tool-developing expenses. Despite being widely used in the industry, a process parameter that has been barely researched is the influence of blankholder force on the drawability of advanced high-strength steels, which contains multiple phases on microstructural level. The main aim of the present study was to analyze the influence of the blankholder force on the formability of DP600 steel. Blankholder forces of 130, 80 and 58 tons were considered. The experimental results led to a detailed understanding of the blankholder force influence during the process. The blankholder force variation promoted different material flow strain rates in the flange during the stamping-higher strain rate increased the bending effect on the die radius. As a result, an experimental approach that allows the blankholder force determination as a function of the different strain rates of the flange flow of the stamped sample was proposed.

Influence of Temperature on the Forming Limits of High-Strength Low Alloy, and Dual-Phase Steels

“…In contrast, the effect of the temperature increase within the forming limits of metals is not completely understood. While for certain materials, the increase in temperature increases the forming limits, in other cases, damages are found with respect to conformability [9][10][11][12][13][14][15][16][17][18][19][20][21].…”

Process and parameters for laser assisted localised heat treatment in manufacturing applications

“…3 To meet weight reduction concerns and safety in crashworthiness events, the use of high-strength steels (HSS) as well as aluminium alloys tends to increase because of their high specific strength. 4–6 However, these materials are characterised by their low formability at ambient temperatures, 7,8 and certain aspects such as wall thinning, springback and process parameters may lead to component failure 9–11 in deep-drawing processes. Tailor Heat Treated Blanks (THTB) feasibility to allow higher geometric complexity of metallic components has been investigated and corroborated.…”

Hole-flange forming of high-strength steel sheet using one-step hot stamping-forging method

“…However, the forming defects such as fracturing, thinning or shrinking can easily occur on the wall of the flange during hole-flanging. Sometimes, the processed blank is large enough to cause failure to neck or tear, 1 even worse to cause the reduction of the joining tensile strength. Lin et al 2 have proposed a new hole-flanging process to obtain flange height and lip accuracy for thick plate.…”