The role of filler wire and scanning strategy in laser welding of difficult-to-weld aluminum alloys

Laser welding of dissimilar aluminum alloys has gained interest over recent years, especially for the production of lightweight components. Pore and crack formation is one of the most critical factors to be taken into consideration for such applications, in particular when one or more parts are produced by die casting or additive manufacturing (AM). Current laser systems offer several methods for defect reduction and process control, while optimized process strategies must be correlated to key factors influencing welding outcomes. In light of these aspects, the current paper investigates the welding of AA6082 sheets with AlSi10Mg parts produced by AM in a lap-joint configuration typical of battery housings in the e-mobility industry. Both laser welding with and without filler wire are investigated, along with the potential advantages of using a wobbling scanning strategy, in order to understand the impact of process strategies on weld bead quality. The importance of process parameter optimization is highlighted for all of the employed strategies, with special emphasis on defects, weld bead chemical composition, joint morphology, and dilution between the materials involved. The findings demonstrate that by introducing filler wire and employing active wobbling, highly reflective alloys can be welded correctly (porosity below 1%, equivalent ultimate strength up to 204 MPa) with good tolerance to variations in process parameters, while filler wire can be excluded in high-productivity welding where linear scanning is employed and detailed optimization of process parameters is performed (porosity below 2%, equivalent ultimate strength up to 190 MPa

Durability and variability of the acoustical performance of rubberized road surfaces

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Laser welding in e-mobility: process characterization and monitoring

The global automotive industry is shifting to e-mobility, where the main challenge is addressed to battery’s mass-production. To keep up with the market demand, high speed production rates and quality products must be accomplished. Since laser welding of dissimilar thins sheets has earned rising demand for battery electrodes connections, a defect-free welding process has to be performed on behalf of a closed-loop monitoring system that updates corrective and/or preventive actions in order to obtain a reliable, “zero waste, zero stop” process. However, nowadays photodiode systems do not allow real-time modification of the parameters, they only tell, at the end of the process, if any signal has gone out of threshold. The objective of this paper is to find correlations between the data collected by the monitoring system with the typical process characteristics of laser welding. Materials investigated are pure copper 300 μm and aluminum 400 μm, processed by means of different sources, length tracks, wavelengths and scanning heads. In this contribution, a Precitec system has been implemented as a possible economical and industrial-oriented solution. The experimental data was analyzed offline and the relationships between technological and signals outputs were evaluated by means of statistical analysis with MATLAB for both Al-Cu and Cu-Al configuration. Findings plotted stable signals if high speeds were set. Results further suggested the power to be the most influent variable for the closed-loop monitoring system and the dependance on the first material irradiated and the laser source used to define the threshold value for the control of the welding process

Vinblastine, bleomycin, and methotrexate chemotherapy plus irradiation for patients with early-stage, favorable Hodgkin lymphoma - The experience of the gruppo italiano studio linfomi

BACKGROUND. The acknowledged effectiveness of vinblastine, bleomycin, and methotrexate (VBM) chemotherapy in patients with early-stage Hodgkin lymphoma has been associated with conflicting toxicity reports. METHODS. One hundred forty-three patients were evaluated clinically and had favorable Stage IA or IIA Hodgkin lymphoma. Ninety-three patients were treated with the standard VBM schedule combined with extended-field radiotherapy (EFRT), leaving the choice of the therapeutic sequence free. Fifty subsequent patients were treated with a slightly modified VBM schedule (VbMp) combined with RT limited to involved fields (IF-RT) and delivered only after the end of chemotherapy. In the VbMp schedule, intervals between cycles were 21 days instead of 28 days, bleomycin doses were reduced, small doses of prednisone were given orally, and the interval before RT was prolonged. RESULTS. Clinical response was complete in 96% of patients who were treated with VBM plus EF-RT and in 94% of patients who were treated with VbMp plus IF-RT. Recurrence rates were nearly identical (12% and 11%, respectively) over necessarily different follow-up (91 months and 33 months, respectively). Hematologic toxicity was tolerable in both trials, and pulmonary side effects were moderate in the first trial and negligible in the second. On the whole, treatment was tolerated better when RT followed chemotherapy. CONCLUSIONS. The VBM regimen was confirmed to be effective in patients with early-stage Hodgkin lymphoma. Administration of all cycles before RT improved tolerance; pulmonary toxicity probably is mitigated further by reduced bleomycin doses, mild prednisone therapy, and a more prolonged resting interval before RT. A slightly higher recurrence rate was expectable in the VBM plus IF-RT trial despite the actual intensification of vinblastine and methotrexate

Long-term survival of stage I multiple myeloma given chemotherapy just after diagnosis or at progression of the disease: a multicentre randomized study

We conducted a randomized trial to evaluate whether melphalan-prednisone (MPH-P) treatment administered just after diagnosis improves survival of stage I multiple myeloma (MM). Between January 1987 and March 1993, 145 consecutive previously untreated patients with stage I MM were randomized between treatment with MPH-P (administered for 4 days every 6 weeks) just after diagnosis and treatment only at disease progression. Survival was not influenced by MPH-P treatment either administered just after diagnosis or at disease progression (64 vs 71 months respectively). Comparing the first with the second group the odds ratio of death is 1.17 (95% confidence interval 0.57–2.42;P = 0.64). Disease progression occurred within a year in about 50% of patients who were initially untreated. Response rate was similar in both groups, but duration of response was shorter in patients who were treated at disease progression (48 vs 79 months, P = 0.044). Patients actually treated at disease progression (34/70) survived shorter than those who had neither disease progression nor treatment (56 vs > 92 months;P = 0.005). Starting MPH-P just after diagnosis does not improve survival and response rate in stage I MM, with respect to deferring therapy until disease progression. However, patients with stage I MM randomized to have treatment delayed and who actually progressed and were treated had shorter survival than those with stable disease and no treatment. Biologic or other disease features could identify these subgroups of patients. © 2000 Cancer Research Campaig