•Effect of ultrasonic pulsed water jet peening on AISI 304 welded joints was investigated.•Significant improvement in surface residual stresses was observed after the peening process.•Improvement in ...surface and sub-surface hardness was also recorded.•Results shows the process as potential method for the surface treatment application.
The residual stress and subsurface hardness of welded joints treated by peening using an ultrasonic pulsed water jet at pressures of 20–60 MPa with various traverse speeds and standoff distances were measured. The effect of the treatment was quantified by measuring the residual stress using X-ray diffraction in three regions (the welded zone, heat-affected zone, and base metal). To analyse the depth of the plastic deformation induced by the pulsating water jet, microstructural analyses and micro-hardness measurements were conducted. The surface topography of the treated samples was examined by measuring the surface roughness using a contact surface roughness profilometer. After pulsating water jet treatment, the samples showed both increased residual stress and surface roughness at pressures of 20–60 MPa. Increased subsurface hardness of the treated region was observed up to a depth of 200–250 µm at pressures of 40 and 60 MPa, deeper than that of the sample prepared at 20 MPa. The microstructural analysis identified the involved plastic deformation phenomenon occurred during the treatment process. This method of surface treatment, where the efficiency of the jet is enhanced by the generation of pulses using an acoustic generator, showed promising results for its practical application as a post-weld treatment method.
The local residual stresses (tensile) generated on the surface of a component during its manufacturing (machining, welding) cause deterioration of its service life. To eliminate the negative effect ...of the stresses, the surface is treated using different methods (shot peening, laser shock peening, heat treatment, water jet peening). The application of ultrasonic technology to modify the continuous jet has been intensively researched for treating advanced stages of erosion. In this work, the modifications in the mechanical properties (tensile strength, micro-hardness and residual stress measurements) of AISI 304 Tungsten inert gas welded joints were investigated after ultrasonic pulsating water jet treatment in the incubation stage of erosion. This revealed that the initial tensile residual stress in the welded joints was converted to compressive stress after the treatment. The micro-hardness of the joints after the treatment increased about 40% in the heat affected zone in the near-surface region. Also, the tensile properties increased by about 37.8% and 34.6% in yield strength and ultimate strength, respectively. The microstructural examination of the near-surface region showed the grain reformation mechanism.
Presented article is focused on the comparison of erosion efficiency on the surface treatment of ultrasonically enhanced PWJ (pulsating water jet) on different metal materials surfaces. Surfaces of ...EN X5CrNi18-10 stainless steel and EN-AW 6060 aluminum alloy were evaluated. Pulsating water jet technological factors were set to the following values: pressure was 70 MPa, circular nozzle diameter was 1.19 mm, traverse speed of cutting head was 100 mm s
−1
(which is 200 impact for millimeter) for stainless steel and 660 mm s
−1
(which is 30 impact per millimeter) for aluminum alloy. The evaluation was made based on the surface topography evaluation, evaluation of microstructure, and microhardness in the transverse cut. The results of the stainless steel surface evaluation show slight erosion of material, with creating microscopic craters. Subsurface deformation was found to a depth of a maximum of 200 μm. Hardness measurement shows 11% higher value of hardness under the affected area compared with a measurement in the center of the sample. From the findings, subsurface deformation strengthening of stainless steel with minimal influence of material surface can be assumed. Surface deformation of aluminum alloy is characterized by the formation of more pronounced depressions and less pronounced protrusions. Depressions were created by a combination of compression and tearing off material parts. A decrease in hardness value of 18% compared with a measurement in the center of the sample. In places of the first indent just below the disintegrated area (up to 600 μm deep), it is possible to assume the material plastic deformation, but the value of aluminum alloy tensile strength
R
m
is not exceeded. The experimental results from an aluminum alloy evaluation do not confirm the subsurface mechanical strengthening of the material.
This study compared the effect of the interaction time of periodic water clusters on the surface integrity of AISI 304 tungsten inert gas (TIG) welded joints at different excitation frequencies, as ...the effect of the technological parameters of pulsating water jet (PWJ) on the mechanical properties of TIG welded joints are under-researched. The TIG welded joints were subjected to different frequencies (20 and 40 kHz) and traverse speeds (1-4 mm/s) at a water pressure of 40 MPa and a standoff distance of 70 mm. The effect of the interaction of the pulsating jet on the material and the enhancement in its mechanical properties were compared through residual stress measurements, surface roughness, and sub-surface microhardness. A maximum enhancement in the residual stress values of up to 480 MPa was observed in the heat-affected zone, along with a maximum roughness of 6.03 µm and a maximum hardness of 551 HV using a frequency of 40 kHz. The improvement in the surface characteristics of the welded joints shows the potential of utilizing pulsed water jet technology with an appropriate selection of process parameters in the treatment of welded structures.
This work is focused on the analysis of the influence of welding on the properties and microstructure of the AISI316L stainless steel tube produced by 3D printing, specifically the SLM (Selective ...Laser Melting) method. Both non-destructive and destructive tests, including metallographic and fractographic analyses, were performed within the experiment. Microstructure analysis shows that the initial texture of the 3D print disappears toward the fuse boundary. It is evident that high temperature during welding has a positive effect on microstructure. Material failure occurred in the base material near the heat affected zone (HAZ). The results obtained show the fundamental influence of SLM technology in terms of material defects, on the properties of welded joints.
Businesses are constantly trying to improve their production by looking for bottlenecks to improve their market position. The introduction and innovation of automated production lines is necessary ...for both labor shortages and productivity and quality reasons. A combination of precision, fluidity, and speed, that is the basic definition of a production line. With the advent of new technologies, production lines have also begun to continuously speed up and innovate. Innovation is the subject of this paper, where the problem of designing a completely new layout for a new production line in the food industry has been addressed. The aim of this paper was to create a design for the optimal layout of the production line in preselected production areas. Optimal use of the space allocated for production is very important for every company today.
This work explores the possibility of repairing damaged pressure piping systems using composite repair bandaging technology. Loctite technology from Henkel was selected from several existing methods ...and applied at the weld joint. To assess the performance of the bandage, a bore was made at the weld joint to simulate a replacement defect of the composite bandage. The bandage, along with the welded joints, was subjected to microstructural and macrostructural analysis, and mechanical and fire resistance tests were also performed. Based on the obtained results, it is concluded that the properties of the Loctite composite system are suitable for repairing pressure piping in the power industry. However, it is not always possible to use this repair method due to certain boundary conditions for its application, such as maximum pipe overpressure, the temperature of the internal medium and the environment, degradation of the repair system due to the medium being transferred and the environment, reduction of the pipe wall at the repair site, possible surface treatment before application of the system, etc. For these reasons, the repair system may be used for a temporary period (approved by the power plant operator), and the spot will then be repaired in the standard way by replacing parts of the pipeline during a planned equipment shutdown.
•Possible extented service life of pipelines by bandaging.•Composite bandage application in energetic industry.•Bandage application on welded joints in pipelines to postpone the shutdown of the power plant.•Testing of composite bandages on pressurized pipeline during conditions simulating earthquake and against fire.
The goal of the submitted paper is to implement the principles of TPM and to achieve almost 100% usability of machines, when there will be no failures and unwanted incidents. The effectiveness of ...implementing the TPM principles has been experimentally verified in an engineering company. Workplaces for the assembly of rails on Unimatic lines were chosen as a pilot workplace. Prior to the implementation of the TPM, analyses of technical downtime and unplanned shutdowns of the manufacturing devices due to failures, unplanned repairs and maintenance were carried out. The resulting analysis concentrated mainly on two main variables - total cumulative technical downtime at individual workplaces and frequency of occurrence of failures in individual sections of the workplaces. The presented approach and the results obtained underline the importance of applying the TPM principles in practice and their indisputable contribution to the ability to increase business performance. The TPM's progressive maintenance management system represents a prerequisite for the reduction of production costs and losses resulting from unscheduled failures now and in the future.
Nowadays the automotive industry is predominantly using heterogeneous welded joints. The welding of an austenitic and galvanized steel sheet is one of the most common applications, which are using ...resistive spot welding (RSW); it is a process in which contacting metal surfaces are joined by the heat obtained from resistance to an electric current. The electrodes used influence the quality of a heterogeneous welded joint. This paper describes the influence of the electrodes used, their material and shapes, and the final heterogeneous welded joint, which consists of two or three sheets. They will be compared with each other two electrode materials: CuCr1Zr original (material used for both electrodes) of new material CuCr1Zr (upper electrode replacement) and CuCo2Be (removable bottom electrode). Furthermore, the improved electrode geometry where the original planar electrode is passed to the electrode with radius surface, due to poor access to the point of welding. The aim of this research was to achieve a better quality of spot welded joints consisting of two or three sheets.
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