Novel welding repair CTOD (crack tip opening displacement) experimental method

Abstract

The invention discloses a novel welding repair CTOD (crack tip opening displacement) experimental method. The experimental method is characterized in that X and K type prefabricated weld grooves are adopted for welding of a prefabricated weld seam; a K type repair weld groove is adopted for the CTOD experiment of a welding heat affected zone; X and V type repair weld grooves are adopted for the CTOD experiment of a weld zone, the advantages of the two are combined, therefore the CTOD fracture toughness value of the most fragile part of a connector can be accurately evaluated, and the performance of a welded joint can be ensured. According to the novel welding repair CTOD (crack tip opening displacement) experimental method, provided by the invention, the form scope of a prefabricated weld groove is enlarged, the success rate of preparation of an effective CTOD sample for a welding heat affected zone can be increased, the application range is wider and the cost is lower.

Description

technical field [0001] The invention relates to the technical field of welding, in particular to a new CTOD experimental method for welding repair. Background technique [0002] CTOD is the acronym for the English name CrackTipOpeningDisplacement, which is called crack tip opening displacement in Chinese, which refers to the relative distance between the two surfaces after the crack tip is subjected to an opening load, often expressed in δ, and the common unit is mm. Sampling for the crack tip opening displacement test, according to the international general standard BS7448, can make samples according to the actual thickness (that is, full-thickness samples). In this way, the size effect of the original structure (plate thickness) is preserved, and the actual welding conditions are well simulated, so the measured toughness will be more accurate and reliable. The value of CTOD reflects the ability of the crack tip material to resist cracking, that is, the toughness of the ma...

AI Technical Summary

Problems solved by technology

At this stage, V-shaped grooves are generally used for CTOD experiments, and surface notch samples are used. The CTOD performance of the center of the weld is fashionable, but for the CTOD performance of the heat-affected zone of the reworked weld, due to the DNV-OS - According to the relevant regulations of the C401 standard, it is necessary to ensure that the distance between the notch position and the weld fusion line does not exceed 0.5mm. Very high requirements, prone to invalid CTOD samples

And usually, when welding is repaired, one side of the repaired seam will be the original weld seam, and the other side will be the base metal. In addition to verifying the performance of the weld seam area during the test, the fusion of these two sides should also be carried out. In this way, if the surface notch sample of the V-groove is used to evaluate the CTOD performance on both sides, it will have a great impact on the welding process (the balance and consistency of the flatness parameters of the groove) and the sample preparation process (the position of the crack tip of the prefabricated fatigue crack). There are very high requirements, and invalid samples are also prone to appear, resulting in the extension of the welding test plate and the increase of the test cost

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