Stress corrosion behavior of narrow-gap rotating laser welding of thick Al-Mg alloy joint

The stress corrosion resistance of 30 mm-thick narrow-gap rotating laser welding (NG-RLW) 5A06 aluminum (Al) joint was investigated by slow strain rate testing (SSRT). The results show that the average ultimate tensile strength (UTS) of the joints in 3.5% NaCl solution is about 11% lower than that in air, and its elongation is only half of that in air. The stress corrosion index [Formula: see text] of the joint is [Formula: see text], which is at the middle level of the range of [Formula: see text]. Moreover, the failure positions of the SSRT specimens in air are weld metal (WM), while the failure positions in the corrosive medium are base metal (BM). This indicates that the stress corrosion resistance of BM is slightly lower than that of WM due to the different microstructures. Many dimples are formed on the fracture surface of the specimen in air, which is a typical ductile fracture. But the fracture surface shows the characteristics of ductile and brittle mixture with obvious corrosion products. This result indicates that the NG-RLW 5A06 Al joint has a tendency to brittle fracture in 3.5% NaCl solution.

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Effect of Heat Treatments on Stress Corrosion Behavior of 7050 Al Alloys in 3.5% NaCl Solution

Materials Science Forum ◽

10.4028/www.scientific.net/msf.877.543 ◽

2016 ◽

Vol 877 ◽

pp. 543-549

Author(s):

Wei Wei Ren ◽

Xing Feng Zhan ◽

Lin Chi Zou ◽

Qiang Li ◽

Jun Feng Chen

Keyword(s):

Corrosion Resistance ◽

Strain Rate ◽

Stress Corrosion ◽

Corrosion Behavior ◽

Electrochemical Impedance ◽

Heat Treatments ◽

Al Alloys ◽

Slow Strain Rate ◽

Nacl Solution ◽

Stress Corrosion Resistance

Effect of heat treatments on the stress corrosion behavior of 7050 Al alloys in 3.5% NaCl solution has been investigated using slow strain rate tensile (SSRT) test. During the slow strain rate tensile process, electrochemical impedance spectroscopy (EIS) in real time was carried out to characterize the electrochemical behavior for different tempers 7050 Al alloys. The investigation shows that both the stress corrosion resistance of 7050 Al alloys is controlled by heat treatments due to the different precipitates state. The improvement of stress corrosion resistance is contributed to the tiny precipitates in matrix which are beneficial to corrosion potential and maintain passivation, and precipitates discontinuous distribution at grain boundary which obstruct intergranular crack connection. Moreover, base on the results, we find out retrogression and re-aging (RRA, i.e., T6 + 200 °C/ retrogression + water quench + T6) increases both tensile strength and stress corrosion resistance. The optimized of retrogression time is 30 minutes.

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UNILOY 326

Alloy Digest ◽

10.31399/asm.ad.ss0241 ◽

1970 ◽

Vol 19 (7) ◽

Keyword(s):

Stainless Steel ◽

Corrosion Resistance ◽

Physical Properties ◽

Stress Corrosion ◽

Tensile Properties ◽

High Strength ◽

Heat Treating ◽

Distinct Advantage ◽

Two Phase ◽

Stress Corrosion Resistance

Abstract UNILOY 326 is a two-phase, ferromagnetic stainless steel characterized by high strength and very good general and stress corrosion resistance. It has distinct advantage for the fastener industry. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-241. Producer or source: Cyclops.

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