scholarly journals Influence of Corrosion of Self-Piercing Riveted High Strength Aluminium Alloy Joints with Button Cracks on the Mechanical Strength

2018 ◽  
Vol 5 ◽  
Author(s):  
Dezhi Li ◽  
Li Han ◽  
Andreas Chrysanthou ◽  
Mike Shergold
Keyword(s):  
Fatigue Strength ◽  
Mechanical Strength ◽  
Galvanic Corrosion ◽  
Salt Spray ◽  
High Strength ◽  
Peel Strength ◽  
Lap Shear ◽  
Obvious Change ◽  
Shear Fatigue ◽  
Small Cracks

For high strength aluminium alloys, such as AA6008T61 and AA6111 PFHT, when they are joined as the bottom material by self-piercing riveting (SPR), they tend to crack at the joint buttons. These cracks, especially those penetrated to the rivets, may cause galvanic corrosion problem with the steel rivet. In this paper, the mechanical strength of four stack/die combinations with different joint button cracking severity was studied before and after salt-spray corrosion test. The results showed that corrosion on the severely cracked joints was worse than that on the joints with small cracks and the corrosion on the stack with the same top and bottom material was less than that on the stack with different top and bottom materials. For all joints the static lap shear strength after corrosion was improved, but the static T peel strength after corrosion was slightly reduced or did not have obvious change. The results also showed that after corrosion the lap shear fatigue strength of the specimens with severe cracks did not have obvious change, but the lap shear fatigue strength of the specimens with small cracks slightly reduced.

Influence of Die Profiles and Cracks on Joint Buttons on the Joint Quality and Mechanical Strengths of High Strength Aluminium Alloy Joint

2012 ◽  
Vol 548 ◽  
pp. 398-405 ◽  
Author(s):  
De Zhi Li ◽  
Li Han ◽  
Zong Jin Lu ◽  
Martin Thornton ◽  
Mike Shergold
Keyword(s):  
Aluminium Alloy ◽  
High Strength ◽  
Bottom Layer ◽  
Peel Strength ◽  
Lap Shear Strength ◽  
Lap Shear ◽  
Increase Productivity ◽  
Small Cracks ◽  
Joint Quality ◽  
Mechanical Strengths

Currently, self-piercing riveting (SPR) is a major technology used by manufacturers to join aluminium body structures to reduce vehicle weight. Normally, for SPR of one specific stack more than one die, rivet, and velocity combination can be applied. Which parameter combination is chosen is depending on the surrounding joints. In order to increase productivity and reduce the number of robots used, it is preferred to use the same rivet/die combination for as many joints as possible. This means for the same stack, different die may be used. To see the influence of die profiles on joint quality, a DF die, which would generate severe cracks and a DC die, which would generate no cracks or only small cracks, were used to join two stacks with a high strength aluminium alloy, AA6008T61, as the bottom layer. The joint quality was analyzed, and the static and fatigue strengths of these stacks were studied. Results showed that cracks on joint buttons might reduce static and fatigue lap shear strength but had no obvious influence on static and fatigue T peel strength for the joints studied.

Fatigue Investigation of High-Strength Concrete Members Reinforced with CFRP

2011 ◽  
Vol 250-253 ◽  
pp. 2202-2205
Author(s):  
Hong Hai ◽  
Li Sun ◽  
Ying Hua Zhao
Keyword(s):  
Fatigue Strength ◽  
High Strength Concrete ◽  
Low Cycle Fatigue ◽  
Concrete Strength ◽  
Concrete Structures ◽  
High Strength ◽  
Fatigue Performance ◽  
Plate Interface ◽  
Strength Concrete ◽  
Shear Fatigue

Fatigue damage becomes an emerging problem in lots of concrete structures which will subject to cyclic loadings during their working life. This paper presents a study on interfacial shear fatigue performance of a high-strength concrete structure strengthened by carbon fiber-reinforced plastic (CFRP) plate, which has been established as an effective method for rehabilitation and strengthening of concrete structures. Based on the static test, a new experimental investigation of the shear fatigue performance along the concrete-plate interface under the low cycle fatigue load in the condition of R=0.1 is presented. The main variable is the concrete strength. Compared with the static ultimate strength, fatigue strength decreases. Therefore, a safety factor of the fatigue strength at the interface of CFRP and concrete should be applied in design.

Physical, Chemical, and Crystallographic Characterization of Anodic Coatings on High Strength Aluminum Base Alloys

1976 ◽  
Vol 34 ◽  
pp. 636-637
Author(s):  
R. E. Herfert ◽  
N. T. McDevitt
Keyword(s):  
Sulfuric Acid ◽  
Salt Spray ◽  
High Strength ◽  
Environmental Stability ◽  
Anodic Films ◽  
Sodium Dichromate ◽  
Corrosion Resistant ◽  
Aerospace Applications ◽  
Bond Strengths ◽  
Adhesive Bonded Joints

Durability of adhesive bonded joints in moisture and salt spray environments is essential to USAF aircraft. Structural bonding technology for aerospace applications has depended for many years on the preparation of aluminum surfaces by a sulfuric acid/sodium dichromate (FPL etch) treatment. Recently, specific thin film anodizing techniques, phosphoric acid, and chromic acid anodizing have been developed which not only provide good initial bond strengths but vastly improved environmental durability. These thin anodic films are in contrast to the commonly used thick anodic films such as the sulfuric acid or "hard" sulfuric acid anodic films which are highly corrosion resistant in themselves, but which do not provide good initial bond strengths, particularly in low temperature peel.The objective of this study was to determine the characteristics of anodic films on aluminum alloys that make them corrosion resistant. The chemical composition, physical morphology and structure, and mechanical properties of the thin oxide films were to be defined and correlated with the environmental stability of these surfaces in humidity and salt spray. It is anticipated that anodic film characteristics and corrosion resistance will vary with the anodizing processing conditions.

SANBAR 20

Alloy Digest ◽  
1999 ◽  
Vol 48 (8) ◽  
Keyword(s):  
Wear Resistance ◽  
Fatigue Strength ◽  
Tensile Properties ◽  
High Strength ◽  
Heat Treating ◽  
Steel Company ◽  
High Fatigue ◽  
Molybdenum Steel ◽  
Rolled Condition

Abstract SANBAR 20 is a high-strength chromium-molybdenum steel with high-fatigue strength and excellent wear resistance in the as-rolled condition. The primary application is use as integral drill rods. This datasheet provides information on composition, hardness, and tensile properties. It also includes information on forming, heat treating, and machining. Filing Code: SA-501. Producer or source: Sandvik Steel Company.

Increasing the fatigue strength of high-strength steel parts by repeated treatment with shot peening

2020 ◽  
pp. 79-82
Author(s):  
G.N. Kravchenko ◽  
K.G. Kravchenko
Keyword(s):  
Fatigue Strength ◽  
Shot Peening ◽  
High Strength Steel ◽  
High Strength ◽  
Resource Recovery ◽  
Repeated Treatment ◽  
Multiple Processing

The effectiveness of multiple hardening by shot peening of samples made of «30ХГСН2А» high-strength steel to increase their fatigue strength is experimentally established. Repeated hardenings allow not only to restore the original durability and even significantly increase it. Keywords fatigue strength, durability, resource recovery, multiple processing by shot peening, repeated hardening, high-strength steel. [email protected]

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.

scholarly journals Application of Commercial Surface Pretreatments on the Formation of Cerium Conversion Coating (CeCC) over High-Strength Aluminum Alloys 2024-T3 and 7075-T6

Metals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 930
Author(s):  
Juan Jesús Alba-Galvín ◽  
Leandro González-Rovira ◽  
Francisco Javier Botana ◽  
Maria Lekka ◽  
Francesco Andreatta ◽  
...  
Keyword(s):  
Electrochemical Impedance ◽  
Salt Spray ◽  
Aluminum Matrix ◽  
Optical Emission ◽  
High Strength ◽  
Chemical Conversion ◽  
Conversion Coating ◽  
Neutral Salt ◽  
Corrosion Properties ◽  
Surface Pretreatment

The selection of appropriate surface pretreatments is one of the pending issues for the industrial application of cerium-based chemical conversion coatings (CeCC) as an alternative for toxic chromate conversion coating (CrCC). A two-step surface pretreatment based on commercial products has been successfully used here to obtain CeCC on AA2024-T3 and AA7075-T6. Specimens processed for 1 to 15 min in solutions containing CeCl3 and H2O2 have been studied by scanning electron microscopy coupled with energy-dispersive X-ray analysis (SEM-EDX), glow discharge optical emission spectroscopy (GDOES), potentiodynamic linear polarization (LP), electrochemical impedance spectroscopy (EIS), and neutral salt spray (NSS) tests. SEM-EDX showed that CeCC was firstly observed as deposits, followed by a general coverage of the surface with the formation of cracks where the coating was getting thicker. GDOES confirmed an increase of the CeCC thickness as the deposition proceed, the formation of CeCC over 7075 being faster than over 2024. There was a Ce-rich layer in both alloys and an aluminum oxide/hydroxide layer on 7075 between the upper Ce-rich layer and the aluminum matrix. According to LP and EIS, CeCC in all samples offered cathodic protection and comparable degradation in chloride-containing media. Finally, the NSS test corroborated the anti-corrosion properties of the CeCC obtained after the commercial pretreatments employed.

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