Materials Science Forum Vol. 818

Abstract: Various ferrous and non-ferrous materials and their combinations are used in car body production in automotive industry. The most commonly used method for joining the materials is resistance spot welding. Some materials or combinations of materials are very difficult or impossible to join by resistance spot welding. Therefore, car producers are seeking for alternative joining methods. One of the innovative joining alternatives is clinching. The paper presents the results of evaluation of clinched joint properties. The high-strength dual-phase steel sheet DP600 in combination with the drawing grade steel sheets DC06, DX53D+Z and DX51D+Z were used for experiments. The influence of position of the sheets relative to the punch and die of the tool on the carrying capacities of the clinched joints was observed as well. The tension test and metallographical analysis were used for the evaluation of clinched joint properties.

Abstract: This material presents the results of the quality evaluation of the weld joints on helically welded pipes, diameter DN 800 mm, made of HSLA steel X 70 (L 485 MB EN 10208-2) with a wall thickness of 11mm. The pipes designed for transportation of natural gas were submerged arc welded by method 121 EN ISO 4063. The filler material used was welding wire OK Autrod 12.24, and the basic flux S A AB 1 67 AC H5 EN ISO 14 174 in two grain-size ranges (0.2-0.8 mm) and (0.8-1.6 mm). The quality of the weld joints was evaluated using a visual inspection, radiation inspection, static tensile test, impact strength tests, macroscopic and microscopic analysis of the weld joints using the light microscopy. The analysis confirmed only minimal differences in the quality of weld joints in favor of the joints welded by the filler with 0.8-1.6 mm grain-size.

Abstract: Currently, the laser technology are used a broad-spectrum in combination with modern computer technology, especially in the field of engineering, energetics, electronics, medicine and the military. In engineering laser technologies record in coupling with robotization allowing five dimensional movements the biggest development mainly in the automotive industry. The most commonly are used for the heat processing of materials, cutting and in particular welding. The technology of laser welding is used in various industries. The thermal cycle at laser welding is usually faster than conventional arc technologies that lead to the small widths of welds and heat affected zones. To satisfy of difficult requirements of current time by this technology, it has to constantly develop and progress. Therefore, it is necessary to evaluate the quality of made products and thus to guide the production in direction towards improving their resulting properties. The paper is focused on the evaluation of mechanical properties, metallography and measurement of microhardness of automobile body sheets connected by laser welding.

Abstract: Resistance spot welding has been widely used in sheet fabrication for several decades. Development of new materials leads to innovation of welding processes. The paper describes the principle of innovative welding method known as Delta Spot and evaluates the properties of Delta Spot joints made by combination of galvanized steel sheets H220PD (a₀ = 0.9 mm) and TRIP 40/70+Z100MBO (a₀ = 0.77 mm). The quality of welded joints was evaluated by tensile test and metallographic analysis. The influence of the welding parameters on the structure of welded joint was observed too. The properties of Delta Spot joint were compared to the properties of standard resistance spot welds.

Abstract: Particleboard is a wood based composite extensively used in wood working. Drilling is the most commonly used machining process in furniture industries. The surface characteristics and the damage free drilling are significantly influenced by the machining parameters. The thrust force developed during drilling play a major role in gaining the surface quality and minimizing the delamination tendency. In this study trials were made eighteen durability tools for different values of the parameters analyzed cut. Based on the results obtained from the study, the effect of cutting parameters selected signals of axial force and torque cutting. Proposed mathematical models using ANOVA, allowing to estimate the cutting forces.

Abstract: The paper presents results of quality analysis of the welded joints realized by CO2 laser (AF8P) using automotive body sheets and sheets for car chassis. There were used double-sided galvanized steel sheets of different grades and thicknesses. Welded joints were evaluated visually and then carrying capacity of the joints was established using tensile test. Welded joints were tested by following destructive tests: microhardness, macro and microstructure of the joints on metallographic sections using light microscopy. Results showed that the welding parameters were chosen appropriately.

Abstract: Drilling is the most commonly used machining process in furniture industries. In this study the eighteen tests of tool durability for different values of the analyzed cutting parameters were carried out. Based on the results of investigations, the influence of selected parameters on the cutting surface quality was determined. Mathematical models based on analysis of variance (ANOVA), allowing to estimate the surface quality in the cutting process were proposed.

Abstract: The paper presents the evaluation of limit deformations by the tensile test of notched specimens to measure the left side of forming limit curve. The notch radii R5, R10, R17.5 and R25 were machined on the specimens of 40 mm in width. The limit deformations have been assessed for Zn coated high strength steel TRIP with thickness 0.76 mm. Two types of deformation grid were electrochemically etched on the specimens: circles with diameter of 2 mm and the pattern of dots with diameter 0.5 mm and spacing 1 mm. The tensile test of notched specimens has been also numerically simulated. The experimentally measured limit curves have been compared to the mathematic Swift-Hill model.

Abstract: The paper deals with optimization of forming process for AISI 430 stainless steel with nominal thickness 0.4 mm. During forming of sidewall for washing machine drum, some wrinkles remain at the end of forming process in some places. This problem was solved by optimization the geometry of the drawpiece using numerical simulation. During optimization a series of modifications of the part geometry to absolute elimination of wrinkling was performed. On the basis of mechanical tests, the material model was created and imported into the material database of Autoform simulation software.

Abstract: The non-destructive inspection of duplex steels is a big challenge, being composed of ferrite and austenite, have some particularities. When using ultrasound, for instance, its waves propagate well in ferrite, but suffer strong attenuation, scattering and refraction in austenite. The aim of this work is to use the Phased Array ultrasonic inspection method for the thin (4 mm) duplex steel weld joint inspection. The experimental sample was made ​​of duplex steel shaped tube with an outer diameter of 44 mm and a wall thickness of 3.8 mm welded with a laser beam. The experiment was necessary to verify attenuation of duplex steel. On the base material and the weld joint were made the artificial defects, in which the adjusted sensitivity of the ultrasonic device was set.The result of the measuring was the defect echo coming from the weld root layer. The length (about 25 mm) can only be estimated due to the inaccurate constant velocity of probe motion along the surface.