INTERNATIONAL ANNUAL CONFERENCE

Cameroon welding association is committed to sharing knowledge through events gathering peers in welding field. The conference is intended to give an opportunity to Experienced and Youngs researchers to share their researches.

• Contribution of the development of welding in Africa in general and in Cameroon in particular
• Welding and associated fields: Training and Jobs.
• Welding
• Sheet metal
• Strength calculation
• Professionalization and performance of professionals in the field.
• Restructuring of the CWA

The present study focuses on the development of an artificial neural network (ANN) based algorithm for the prediction of cooling times of a dissimilar weld joint of high strength steels S700MC and S690QC, using gas arc welding (GMAW). The neural network developed has a 4-20-1 architecture with input parameters of the station voltage (U), the intensity of the welding current (I), the welding speed (V) and the input of heat (Q) with the cooling time (∆t_8/5) as output parameter. A protocol was set up with MATLAB R2020a software including three neural network systems to determine which one had the lowest mean square error (MSE): the first system generated using 14 experimental data produces an MSE of 1.295×10^-3 and a regression R=0.995 with a relative error of 0 for 8 of the 14 initial data; the second system generated by 15 analytical data obtained by calculation produced an MSE of 4.278×10 ^-3 with a regression R=0.978 with 11/15 showing an error of 0; the third system consisting of experimental data combined with analytical data produced an MSE of 2.506×10^-3 with regression R=0.972 with a slight difference between the input data and the predicted data on all 29 points. The results obtained by the first two systems are satisfactory and the neural networks developed can be considered reliable for predicting the cooling times of welded joints of high strength steels.

Keywords—Artificial neural network, dissimilar welding, heat affected zone, cooling time, high strength steels.

A36 steel has been the popular choice of structural material as it is abundantly available, inexpensive and has adequate mechanical properties. It has a high general corrosion rate which causes rapid degradation of materials in engineered products. This study examined and analyzed the impacts of corrosion on A36steel welded structures in areas with high humidity and sodium chloride (NaCl) levels. A cyclic (wet/dry or immersion/exposure) accelerate corrosion test was used. To proceed with this, 20 weld specimens of same geometric characteristics (145mm x 40mm x 1mm) were subjected to an accelerated corrosion test (ACT) in 10 different solutions of NaCl and H2O. In each solution, two samples were being immerged for 2hs and later exposed for 96hs and the cycle lasted for 2 Months. The ASTM G1-03 standard (2002) was used to calculate uniform corrosion due to mass loss rate (MR) of the 10 specimens, and pitted corrosion on the 10 coated specimens in same conditions. Gravimetric weight loss measurements and Microstructure observations were performed to figure out the degradation of the corroded region. A correlation between the results of corrosion rate gotten in the accelerated corrosion test and that of real situation was made. In anticipation, the outcome of this work should reveal that, A36 steel welded structures in Douala especially those located around the sea shore exposed to 5.5% sea salt, Ph value of 6, humidity content of 87, will corrode at a rate that, does not meet the acceptable corrosion value of 0.0254mm/year set by ASTM for A36 steel. An improvement in corrosion prevention techniques is of interest.

Keywords—A36 steel, Arc welding, pitted corrosion, crevice corrosion, film thickness

The analysis of the thermomechanical behavior of dissimilar weld joints between A36 and 316L steels is essential to guarantee the robustness and durability of structures used in industrial environments. This study of dissimilar welds is a method commonly used in industrial construction to combine the specific properties of each material and meet particular technical requirements. By studying how these two materials interact under different thermal and mechanical stresses, it is possible to optimize the design of solder joints to ensure optimal performance. To achieve our goals, we worked on a plan: experimental analysis, regarding this analysis the samples were welded using electric arc welding processes (TIG, MAG) at constant welding intensities and the Tensile test was carried out using the universal tensile testing machine 50 KN – WDW50. The experimental analysis shows that for the elongations in TIG welding 12.077% we have an elastic tensile strength of 390.00 MPa which presents the fatigue start point from which we enter the plastic zone which shows the performance of the weld joint on the two steels with a maximum stress substantially equal to 500 MPA. The experimental analysis shows that for the elongations in MAG welding 8.727% we have an elastic limit resistance 327.88 MPa which presents the fatigue start point from which we enter the plastic zone which shows the performance of the weld joint on the two steels with a maximum stress approximately equal to 430 MPa.

Keywords—Thermomechanics; dissimilar welding; TIG; MAG