Global and Local Corrosion of Welded Joints of High-Strength Low-Alloy Automotive Steel (original) (raw)
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Advanced Technologies & Materials
Experimental investigations were carried out to study the effect of weld joint designs and post weld heat treatment (PWHT) on mechanical and corrosion properties of low carbon steel. Butt, bevel and half-lap joints were produced with a voltage of 20 V and current of 110 A with the use of 3.2 mm diameter electrode E6013. Full annealing was carried out on part of the welded samples in order to consider the possibility of post weld heat treatment for better performance. The mechanical properties (tensile, hardness, and impact toughness) were studied for both the as welded (AW) and PWHT samples as well as the corrosion performance in a natural sea water environment containing 3.5 wt.% NaCl using potentiodynamic polarization method. The microstructure of the AW and PWHT samples of the welded joints with the most promising mechanical and corrosion properties were then characterized by means of an optical microscopy. The results obtained reveals that the bevel joint followed by half lap jo...
Zastita materijala
The paper presents the results of stress corrosion resistance studies of welded joints of low-alloy steel 17G1SU, obtained by high-frequency welding (HFW). The potentiometry method has established that the welded joint in the state after welding and after linear heat treatment is resistant to corrosion, because the potential difference between the weld and the base metal does not exceed (30-50) mV. According to the results of accelerated corrosion-mechanical tests in 3% NaCl under conditions of constant load under different stress, it was found that the rate of uniform corrosion of both types of welded joints is almost the same as the base metal. Slightly higher corrosion rate of the welded junction after linear heat treatment correlates with the electrochemical data. In general, the welded joint, made according to the factory technology, has resistance to corrosion and mechanical destruction in a solution of 3% NaCl at the level of the base metal, in the absence of weld defects. In...
ASSESSMENT OF CORROSION RATE OF DISSIMILAR WELDED METALS: GRAVIMETRIC ANALYSIS
2015
Assessment of rate of corrosion of mild steel, galvanized steel, stainless steel, zinc and dissimilar welded metals (mild steel and galvanized steel, mild steel and stainless steel, mild steel and zinc, galvanized steel and stainless steel, galvanized steel and zinc) immersed in acid (0.4 M HCl) and base (20% NaOH) test solution. The weight loss, corrosion rate and metal loss were determined. The results of this study revealed that samples corrosion rate increase with increase in exposure time and galvanic corrosion depends on the standard electrode potential of the samples. The corrosion rate of the metal plates and dissimilar welded metals immersed in acid test solution (0.4 M HCl) increases in this order; zinc < galvanised steel < mild steel < mild steel and galvanised steel < mild steel and zinc < galvanised steel and zinc < galvanised and stainless steel < stainless steel and zinc < mild steel and stainless steel < stainless. The corrosion rate of the metal plates and dissimilar welded metals immersed in base test solution (20% NaOH) increase in this order; stainless steel < galvanised < zinc <mild steel and stainless steel < galvanised and stainless steel < mild steel and galvanised steel < mild steel < galvanised steel and zinc < mild steel and zinc < stainless steel and zinc. Accelerated galvanic corrosion occur in welded samples of mild steel and galvanised steel, mild steel and stainless steel, mild steel and zinc, galvanised steel and stainless, stainless steel and zinc. No accelerated galvanic corrosion was observed in galvanised steel and zinc.