Piercing and Surface-Crack Defects in Cold Combined Forward-Backward Extrusion

Metal flow tends to be complex and difficult to predict in the combined forward-backward extrusion (CFBE) process. Piercing and surface-crack defects are phenomenal in forming fasteners featuring a forward extruded pin and a backward extruded cup. In this work, a series of the CFBE tests with variou...

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Bibliographic Details
Published inApplied sciences Vol. 11; no. 9; p. 3900
Main Authors Lin, Heng-Sheng, Lee, Chien-Yu, Li, Wen-Shun
Format Journal Article
LanguageEnglish
Published Basel MDPI AG 01.05.2021
Subjects
Backward extrusion
Cold
Cold extrusion
combined forward-backward extrusion
Cracks
Extrusion
Extrusion rate
Fasteners
Forming limit diagrams
Forward extrusion
fracturing damage
Investigations
Magnesium alloys
Metal forming
Piercing
piercing defect
Simulation
surface-crack defect
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Summary:Metal flow tends to be complex and difficult to predict in the combined forward-backward extrusion (CFBE) process. Piercing and surface-crack defects are phenomenal in forming fasteners featuring a forward extruded pin and a backward extruded cup. In this work, a series of the CFBE tests with various combinations of the forward extrusion ratio (FER) and the backward extrusion ratio (BER) were conducted. A forming limit diagram, detailed with the piercing and surface-crack defects on the forward extruded pin or the backward extruded cup, was developed to provide a conception in choosing appropriate extrusion ratios in forming fasteners with such pin-and-cup features. With the aid of the forming load-stroke curves and the finite element analysis of fracture damage, the fracturing mechanism for the CFBE process was provided.
ISSN:2076-3417
2076-3417
DOI:10.3390/app11093900