The paper describes the process of reduction of welding residual stresses by the application of a pressure test at which acoustic emission (AE) pulses are recorded to monitor the plasticization of the material, which guarantees the proper reduction of stresses after unloading of the vessel. Specimens with deposited welds were tensile loaded, strains were measured and AE pulses recorded. Tests have also been performed on pressure vessels with remelted zones on their shells with simultaneous recording of pressure, hoop strain and AE signals. The results confirmed that the RMS value of AE can be used for monitoring of the mechanical stress relieving process, as it sharply increases when reaching by the vessel material the 0.5 % plasticization.
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