The present dissertation deals with the application of acoustic emission testing (AET) as one of the non-destructive testing to identify the quality of metal materials used in agricultural technology. Experimental study is divided into two parts. The first part is the use of AET in welding by Cold Metal Transfer (CMT). The quality of the welding process and the welded specimens is evaluated, especially in corrosion and mechanical degradation. Second part is devoted to magnesium alloys which are currently being used in the automotive industry and have the potential utilization in specific agricultural applications as well. Research in this area is focused on the evaluation of high-cyclic fatigue at different stages of corrosion degradation of magnesium. The problems of weldability of the material are solved. Attention is also focused on the CMT welding of two dissimilar materials, especially in AZ31B magnesium alloy and EN AW 6065 aluminum alloy, further DX51D galvanized steel and aluminum alloy. Results declare a way to use AET for qualitative evaluation of the welding process and process of mechanical and corrosive degradation of specimens. The efficiency of AET during the cooling phase after welding was demonstrated. These records are used to optimize the welding process. The mechanical resistance of the specimens with and without corrosion in tensile and fatigue tests was detected and visualized by means of AET. The high-frequency pulsator was used for practical evaluation of the quality of magnesium alloys under dynamic loading. The degree of reduction of fatigue life due to corrosion degradation was visualized by application of AET. The work presents the applicable results of using AET in the qualitative evaluation of innovative materials during mechanical and corrosive degradation as well as during the welding process. Therefore, the sense of this work is to deepen knowledge about the potential of modern approaches for qualitative assessment in order to identify new areas of specific material application, improving production quality and safety as well as reducing costs. The work was supported by the Internal Grant Agency AF MENDELU.

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The diploma thesis titled "Quality assessment by non-destructive technologies" is focused at evaluation degradation qualities of welded components, which are material heterogeneous. Welded samples are made for experimental measuring by CMT method and their degradation qualities are measured by the acoustic emission during the corrosion process and tensile straining. The theoretical part is aimed at on basic division most used method NDT, the main stress is on AE. Te final part is focused on corrosion engineering, especially on problematic galvanic corrosion, which is important in case of interaction of homogenous materials. Material samples which were used are mentioned at the beginning of experimental part. Then the thesis is dedicated to summary of methods used during the measurement. The next chapter provides courses and exp. results of observations and measurements using AE. Courses and exp. results of observations and measurements using AE are in the last chapter.

This diploma thesis: Transformation of the dynamic resistance of stainless steels due to structural inhomogeneity deals with the effects of corrosive damage on fatigue properties of stainless steels. The theoretical part deals with general principles of creation and chemical reactions, the factors affecting their speed, as well as, fatigue properties of materials (formation of cracks, stages of high cycles fatigue, fatigue slip zone etc.) and description of the method of non destructive testing the acoustic emission. The practical part describes executed experiment which focuses on comparing the results of fatigue tests between the standards and thermal and corrosion exposed samples. The actual measurements supplement microscopic images of the fracture surfaces and the records acoustic emission during measurements of some samples.

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