Mechanical Investigations of ASTM A36 Welded Steels with Stainless Steel Cladding

The in-service life of ASTM A36 welded steel pipes in power plants is often shortened by ash corrosion. During the heating condition, the ash deposition on the welded steel pipes gradually reduces the thickness of the pipes, thus, reducing the lifetime. Instead of replacing the pipes with new ones, the cost could be significantly reduced if the lifetime could be further extended. Weld cladding was the method selected in this study to temporarily extend the service life of welded pipes. This paper performed the mechanical investigations of A36—A36 welded steel plates after coating the surfaces with 309L stainless steel with a cladding method. The residual stress was also tested to observe the internal stresses developed during the welding processes of A36—A36 specimens. The comparison between the coated and non-coated surfaces of welded steels was performed by using the tensile tests (at room and elevated temperatures), corrosion (pitting corrosion, intergranular corrosion, and weight-loss corrosion) tests, and wear (shot blasting) tests. The life-extension of both coatings was evaluated based on the tensile tests and the corrosion and wear tests provided the qualitative evaluations of the coating performance. The results showed that surfaces coated by cladding could be used to temporarily extend the life of ASTM A36 welded steel under the studied conditions.

THE CORROSION AND WEAR RESISTANCE OF LASER AND MAG WELD DEPOSITS

The paper focuses on the possibility of HPDC molds restoration for aluminium casting by laser and MAG weld cladding with a welding wire of the same grade like the base material. A chemical analysis of the weld deposits showed a decrease in the content of some elements in the MAG deposit due to the higher thermal input to the weld bath. The lower heat input of laser welding has resulted in a higher incidence of fusion defects lack between the weld deposit and the base material. Thermal conditions during welding affected hardness of weld deposits and their abrasive resistance as well. The resistance of materials against dissolution when immersed in AlSi8Cu3 alloy was similar for both deposits and the base metal.

Effect of Cladding Process Parameters for Mild Steel Surface Treatment

Weld cladding process is to improve the wear resistance properties by depositing a layer of wear resistance material over carbon steel plate. It is a process of combining two metals of dissimilar properties with extra fill in between the metals. Selection of process parameters for achieving the required clad bead geometry and its shape relationships is the main problem faced in the mild steel cladding. The cladded bead components quality always depends on clad bead geometry and shape of welds. In order to obtain better quality, wear resistance property of the metal should be good and also to reduce the manufacturing costs the bead parameters must be optimized. The objectives mentioned above can be achieved by developing mathematical equations to predict bead geometry. The experiments were conducted by depositing stellite6 wire on mild steel plates.

Weld Cladding of s355 Steel with Rectangular Electrode Covered Rutile 2000 s Coating

Weld cladding or weld overlay is a frequently used method for repair welding of damaged surfaces and for production of different surface coatings. The conventional coated electrodes have a circular cross-section. In order to increase the productivity and to decrease dilution and the depth of the heat affected zone (HAZ), the geometry of the electrode core was modified. Experimental weld cladding was carried out with rutile coated electrodes of rectangular cross-sections of 12.56×1 mm2, and for reference, also with a conventional φ 4 mm electrode Rutilen 2000 S. The coating of rectangular electrodes was identical and the core material almost identical to the materials of the standard electrode. The base material was the structural steel 355JR. The goal of investigation was to determine the welding parameters for the rectangular electrodes and to compare geometries and mechanical properties of the welds. Hardness and the dimensions of weld metal and HAZ were measured. Results with the 6.28×2 mm 2 and 6.28×2 mm electrode were similar to the results with the standard electrode. However, with the 12.56×1 mm2 rectangular electrode, significantly lower currents were sufficient to obtain a good quality of the deposition layer. Due to possibility to weld with currents as low as 80-100 A, shallower and smaller HAZs and less dilution can be achieved with the rectangular 12.56×1 mm2 electrode than with standard cylindrical φ 4 mm electrode.