Method for detecting microporous defect at heart part of cold-drawn seamless steel tube

Abstract

The invention provides a method for detecting the microporous defect at the heart part of a cold-drawn seamless steel tube. The method comprises the following steps: selecting sample pieces; performing ultrasonic flaw detection on the sample pieces; regulating a gain knob of an ultrasonic flow detector to ensure that the height of the bottom wave at the first time is A and fixing the gain knob to acquire the ultrasonic flow detector with determined detection sensitivity; scanning the cold-drawn seamless steel tube to be detected by using the ultrasonic flow detector with determined detection sensitivity along the axial direction, recording the height X of the bottom wave at the first time of all parts of the cold-drawn seamless steel tube to be detected, and representing whether the heart part of the cold-drawn seamless steel tube to be detected has the microporous defect or not by using decibel difference 201g(A / X) between the height A of the bottom wave at the first time and the height X of the bottom wave at the first time of a certain part of the cold-drawn seamless steel tube to be detected. According to the method, the microporous defect at the heart part of the cold-drawn seamless steel tube can be conveniently and accurately detected, and the method has the significant meaning on improvement of the quality of real objects of cold-drawn seamless steel tube products.

Description

technical field [0001] The invention relates to the technical field of defect detection of cold-drawn seamless steel pipes. A method for detecting microporous defects in the core of seam steel pipe). Background technique [0002] Usually, cold-drawn seamless steel pipes (referred to as cold-drawn steel pipes) are made by using a hydraulic high-precision cold-drawing machine to pass through a mold of a certain shape under the action of a drawing force, so that the pretreated tube blank undergoes work hardening and plastic deformation. Forming. [0003] The production process of cold-drawn steel pipes is generally: tube blank—annealing or tempering heat treatment (or no heat treatment), pickling, phosphating, saponification—cold drawing into finished steel pipes. [0004] If the tube billet has not been annealed or tempered heat treatment, the effect of annealing or tempering heat treatment on the tube billet is not good, the effect of pickling, phosphating, saponification i...

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Problems solved by technology

[0009] At present, in the relevant materials and documents of the prior art, there is no report of microporous defects in the core of this type of cold-drawn steel pipe, and national standards such as high-pressure gas cylinders and oil cylinders related to cold-drawn steel pipe products do not address this type of defect. detection method

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