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In this paper the analysis of welding technology to mechanical properties of welded joints at high strength low alloyed steel S690QL is presented. Experimental testing was done at models with V-groove butt joints that are done by MMA or MIG for root pass and MAG for other passes of multipass welded joints with related parameters and consumables. Yield and tensile strength, so as answer to load of models are determined experimentally in order to analyses the effect of welding technology to resulted mechanical properties. On the basis of the obtained results it can be concluded that welding parameters have significant influence to mechanical properties of welded joints at high-strength low-alloyed steel. Furthermore, it can be concluded that welded joints with root pass done by MIG and other passes by MAG provide better mechanical properties. Presented research point out that welding parameters at high strength low alloyed steels must be selected and controlled precisely to obtain welding joints with adequate mechanical properties. Welding, as dominant method of joining, is primary factor that provide beneficial application of high-strength low-alloyed steels. The paper highlight the influence of material degradation due to welding. This paper point out the importance of analysing the welded joints at different levels of dimensions, while further, more detailed, research can be continued through development of a numerical model of the welded joints which will complete the experimentally obtained results. As experimentally obtained results correlate to material degradation due to welding it is implicated that future development of high-strength low-alloyed steels must be followed with development and modification of welding processes.

The selection procedure and qualification of the optimal welding technology for the structural steel S355J2G3 are presented in this paper. The considered steel is widely applied for manufacturing the supporting structures in various areas, especially in civil and mechanical engineering. It is delivered mainly in form of plates of various thicknesses and solid profiles of various diameters. Considering that welding is mostly used in manufacturing of structures, it is very important to be aware of possibilities for this steel welding, as well as of problems that may arise during that process. Here are presented: a calculation procedure of the base metal's weldability, selection of the filler metal and the welding technology, with results of experimental testing of the base metal and welded samples. The following experimental investigations were performed: tensile, bending and impact toughness test, metallographic investigations and hardness measurement. All the samples were cut out from the welded plates. Obtained results have shown that the structural steel S355J2G3 is suitable for welding, since there is no danger of appearance of cracks or other defects. With adequate choice of the welding technology the mechanical properties of the welded joint can be comparable to those of the base metal.

In this paper effects of welding on mechanical and microstructural characteristics of high-strength low-alloy steel joints is presented. Testing was done at models prepared with V-groove butt joints that are done by two different welding processes. Considered welding processes were done by MMA or MIG for root pass and MAG for other passes with related consumables. Experimentally determined basic mechanical characteristics were put in correlation to relate ones that were numerically calculated. The experimentally obtained yield strength and tensile strength showed that welding process MMA/MAG provide better mechanical properties then MIG/MAG. It is implicated that selection of welding process at high-strength low-alloy steels is multi criterion analysis. If only proper welding is obtained, applications of high-strength low-alloy steel are adequate. Those applications caused specific problems related to its specific characteristics and properties especially weldability. As welding processes can be analysed from different aspects, selection of specific welding process at high-strength low-alloy steel are more complex.