Improvement of Joinability in Mechanical Clinching of Ultra-High Strength Steel Sheets Using Counter Pressure

2014 ◽  
Vol 966-967 ◽  
pp. 607-616 ◽  
Author(s):  
Yohei Abe ◽  
Shoma Nishino ◽  
Kenichiro Mori ◽  
Toru Kato
Keyword(s):  
High Strength Steel ◽  
Static Load ◽  
Metal Flow ◽  
High Strength ◽  
Steel Sheets ◽  
Counter Pressure ◽  
Tension Tests ◽  
Ultra High Strength Steel ◽  
Mechanical Clinching ◽  
Cross Tension

A mechanical clinching using counter pressure of a rubber disk was developed to join the ultra-high strength steel sheets having low ductility. In the proposed process, the interlock was increased by the increment of metal flow with the counter pressure of rubber disk in the die cavity. The two kind of ultra-high strength steel sheets having different ductility were used in the mechanical clinching. The effect of the shape of rubber disk on the deforming behaviour of the sheets was investigated. The joinability was improved under the appropriate shape of rubber disk for both sheets, and then the sheets having 56% of reduction area were successfully joined whereas the sheets were not joined without the counter pressure. Although the joinability of the sheets having 43% of reduction area was improved, the cracks occurred in the upper sheet around the punch sidewall. The maximum static load and the fatigue limit of the joined sheets were measured in the tension-shearing and cross-tension tests. It was effective for the improvement of joinability in the mechanical clinching of ultra-high strength steel sheets to use the counter pressure of the rubber disk.

Mechanical clinching with dies for control of metal flow of ultra-high-strength steel and high-strength steel sheets

2017 ◽  
Vol 232 (4) ◽  
pp. 644-649 ◽  
Author(s):  
Yohei Abe ◽  
Takato Saito ◽  
Ken-Ichiro Mori ◽  
Toru Kato
Keyword(s):  
Tensile Strength ◽  
Welded Joints ◽  
High Strength Steel ◽  
Metal Flow ◽  
High Strength ◽  
Steel Sheets ◽  
Tension Tests ◽  
Element Simulation ◽  
Ultra High Strength Steel ◽  
Mechanical Clinching

Ultra-high-strength steel sheets having a tensile strength of more than 1 GPa and a low ductility were joined by mechanical clinching with dies for control of metal flow. The bottom angle of the die was modified to increase interlocking between the sheets under avoidance of the sheet fracture. The effect of the die shape on metal flow in the sheet combination including an ultra-high-strength steel sheet was investigated by the finite element simulation and the experiment. As the tensile strength of the steel sheets increased, the joining range was narrow due to low ductility of the sheets. The static and fatigue strengths of the mechanically clinched joints were compared with those of the welded joints. Although the static loads of the mechanically clinched joints were smaller than those of the resistance spot welded joints in both tension-shearing and cross-tension tests, the fatigue loads of the clinched joints were larger. It was found that the mechanically clinched joint has superior fatigue strength.

scholarly journals Mechanical clinching and self-pierce riveting for sheet combination of 780-MPa high-strength steel and aluminium alloy A5052 sheets and durability on salt spray test of joints

2021 ◽  
Vol 113 (1-2) ◽  
pp. 59-72
Author(s):  
Yohei Abe ◽  
Ken-ichiro Mori
Keyword(s):  
Aluminium Alloy ◽  
High Strength Steel ◽  
Salt Spray ◽  
High Strength ◽  
Alloy Sheet ◽  
Galvanized Steel ◽  
Load Reduction ◽  
Minimum Thickness ◽  
Steel Sheets ◽  
Mechanical Clinching

AbstractTo increase the usage of high-strength steel and aluminium alloy sheets for lightweight automobile body panels, the joinability of sheet combinations including a 780-MPa high-strength steel and an aluminium alloy A5052 sheets by mechanical clinching and self-pierce riveting was investigated for different tool shapes in an experiment. All the sheet combinations except for the two steel sheets by self-pierce riveting, i.e., the two steel sheets, the two aluminium alloy sheets, and the steel-aluminium alloy sheets, were successfully joined by both the joining methods without the gaps among the rivet and the sheets. Then, to show the durability of the joined sheets, the corrosion behaviour and the joint strength of the aged sheets by a salt spray test were measured. The corrosion and the load reduction of the clinched and the riveted two aluminium alloy sheets were little. The corrosion of the clinched two steel sheets without the galvanized layer progressed, and then the load after 1176 h decreased by 85%. In the clinched two galvanized steel sheets, the corrosion progress slowed down by 24%. In the clinched steel and aluminium alloy sheets, the thickness reduction occurred near the minimum thickness of the upper sheet and in the upper surface on the edge of the lower aluminium alloy sheet, whereas the top surface of the upper sheet and the upper surface of the lower sheet were mainly corroded in the riveted joint. The load reduction was caused by the two thickness reductions, i.e., the reduction in the minimum thickness of the upper sheet and the reduction in the flange of the aluminium alloy sheet. Although the load of the clinched steel without the galvanized coating layer and aluminium alloy sheets decreased by about 20%, the use of the galvanized steel sheet brought the decrease by about 11%. It was found that the use of the galvanized steel sheets is effective for the decrease of strength reduction due to corrosion.

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