Method for detecting weld defect of stainless steel runner blade of water turbine

Abstract

The invention discloses a method for detecting a weld defect of a stainless steel runner blade of a water turbine, comprising the following steps of: 1, selecting an instrument; 2, calibrating the instrument; 3, drawing a rejection judging line for detection: (1) making a reference block; and (2) testing the detected surface of the reference block through a wedge block by using a probe of the instrument, recording the current gain of the instrument and the height values of reflection wave amplitudes of through holes at different heights in the reference block, drawing points according to the height values of the reflection wave amplitudes on a two-dimensional coordinate system, and connecting the points into a smooth curve to draw the rejection judging line; 4, detecting the weld of the blade; and 5, recording the defect: displaying the height of an echo signal according to the instrument and comparing the height of the echo signal with the rejection judging line by taking the rejection judging line as a reference, making corresponding marks on the surface of the blade, and finally detecting whether the blade has a defect according to the marks on the surface of the blade. By using the method, the weld defect of the stainless steel runner blade can be reliably, conveniently and rapidly detected.

Description

technical field [0001] The invention belongs to a non-destructive testing method, in particular to a detection method for weld seam defects of stainless steel runner blades of water turbines, which is suitable for detecting the upper crown and lower ring weld seams of stainless steel runner blades of large and medium-sized Francis turbine units. Background technique [0002] In recent years, the large and medium-sized Francis turbines for new power generation generally use low-carbon martensitic stainless steel ZG0Cr13Ni4-6Mo for the turbine blades. Penetrating cracks often appear, and some units even have extreme cases where the same position of the runner blade is repeatedly repaired and cracked repeatedly, which seriously affects the safe and stable operation of the hydroelectric generating unit. [0003] The more practical way to completely solve the cracks of stainless steel runners is to use the opportunity of overhaul to remove the cracks and repair them, but the key ...

AI Technical Summary

Problems solved by technology

[0004] The technical problem to be solved by the present invention is to propose a detection method for weld defects of stainless steel runner blades of hydraulic turbines, using ultrasonic phased array Acoustic beam deflection and focusing performance, reliable, convenient and rapid detection of weld defects of stainless steel runner blades, so as to find and deal with defects in time, and avoid runner failure accidents caused by weld defects

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