Influence of Welding Process on Microstructure and Properties of Welded Joint of NM360 Steel Plate Used for Vibration Wh
Welding Process for NM360 Steel
NM360 steel (JIS G3106 SM490A) is a kind of low alloy high strength steel for welded structures which is applied to the manufacture of vibration wheel of road rollers. According to the previous research, NM360 steel has excellent spot and arc welding performance, and the weldable performance is excellent.
Arc welding is the most common and cost-effective welding method for welding the NM360 steel plate. It uses an electric arc created by an electrode to heat and melt the base metal and filler metal. This welding process with NM360 steel plate is commonly known as shielded metal arc welding (SMAW), and it is often used for applying vibration wheel to road roller.
Welding the NM360 steel plate requires the use of a suitable electrode. The shielded metal arc welding (SMAW) electrode depends on the thickness and size of the joint and the metal type, and the common electrodes are E 6010, E 6013, and E 7014. The E 6010 electrode is good for penetrating welds, while the E 6013 and E 7014 electrodes are suitable for out-of-position welding.
The SMAW welding process of the NM360 steel plate involves several operations such as joint preparation, arc striking, electrode feeding and manipulation, current selection, and post-weld treatments. They are essential to establish a satisfactory weld joint with the desired properties.
Microstructure and Properties of Welded Joint
The welding of the NM360 steel plate produces a strongly cracked hazy microstructure. The welded joint contains a blended zone and a heat affected zone. The blended zone is a region of solidification which has a net-like structure, and it is a low-strength zone. The heat affected zone, which is located at the boundary between the blended zone and the base metal, is a region of recrystallized and partially melted grain structure.
The welded joint of the NM360 steel plate has a great influence on its mechanical properties. Compared with the base metal, the hardness and strength of the welded joint decrease due to the weaker welded joint microstructure. The mechanical properties of the welded joint depend on the welding process, and the welded joint of NM360 steel plate is susceptible to different types of defects, such as porosity, cracking, undercutting, and lack of fusion. Thus, controlling the welding parameters during the welding process is of utmost importance in order to achieve mechanical properties as close as possible to those of the base metal.
In conclusion, the welded joint of the NM360 steel plate used for the vibration wheel of a road roller is influenced by the welding process. A suitable process should be applied to the joint to achieve mechanical properties as close as possible to those of the base metal. The welding process affects the microstructure and properties of the welded joint, and it should be chosen carefully for a better welded joint with satisfactory mechanical properties.
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