A kind of fracture cleaning method of nickel base superalloy

Abstract

The invention discloses a nickel-based high-temperature alloy fracture cleaning method. The method comprises the following steps: 1) preparing a cleaning solution; 2) completely immersing the alloy fracture in a cleaning solution, and boiling in a water bath to obtain a primarily cleaned fracture; 3) repeatedly adhering the fracture by using an adhesive tape until the adhesive tape does not adheredirt; 4) brushing the fracture with a brush soaked with an acetone solution; 5) completely immersing the fracture into an HCl solution, and carrying out ultrasonic cleaning; 6) repeating the step 3)and the step 4); 7) taking the fracture as a cathode, taking a platinum electrode as an anode, and carrying out electrolytic cleaning in an HCl solution; and (8) repeating the step (3) and the step (4) until the scanning electron microscope is enlarged by 500-1000 times, cleaning up dirt on the fracture, and distinguishing fracture characteristics. According to the method, oxides on the fracture of the nickel-based superalloy can be effectively cleaned, secondary damage to the fracture is avoided, and sample preparation is made for finding out a real reason causing alloy service failure.

Description

Technical field [0001] The invention belongs to the general inhibition field of metal material corrosion or fouling in the metallurgical industry, and specifically relates to a method for cleaning a fracture of a nickel-based superalloy material. Background technique [0002] Nickel-based superalloys (for example, GH6783, GH2984, GH3625) have been widely used in the manufacture of steam pressure valve bolts in ultra-supercritical power units in recent years. They are affected by vibration, high temperatures around 650°C, water vapor and other external environments. Generally, fracture failure occurs between 20,000 and 50,000 hours of service. [0003] The fracture faithfully records the irreversible deformation of the material before fracture under the action of load and environment, and the whole process of crack initiation and propagation until fracture. It is the most important material evidence for fracture failure analysis. At present, the commonly used methods for cleaning t...

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Problems solved by technology

At present, the commonly used fracture cleaning methods for steel parts with short service time mainly include: (1) Organic solvent cleaning method, such as soaking or scrubbing with gasoline, acetone, alcohol, etc., which is suitable for cleaning the grease and other pollution attached to the fracture surface (2) Ultrasonic method, using an ultrasonic cleaning machine for ultrasonic cleaning, which is suitable for cleaning off loose attachments attached to the surface; (3) dry air flow or soft brush, which is suitable for removing loose particles attached to the surface; ( 4) Chemical etching method, the chemical etching solution is prepared by a variety of reagents, which is suitable for removing denser oxides, the production process is relatively complicated, and there is often the risk of overwashing damage to the fracture morphology due to excessive chemical reactions; (5) ) electrochemical cleaning method, usually using an inert anode (such as carbon and platinum), using the fracture sample to be cleaned as a cathode, and the hydrogen bubbles generated on this sample mechanically remove surface waste and deposits, for example, Ni The electrolyte solution for fracture electrolysis of -Cr-based superalloys is mostly composed of alkali and salt (see literature for details: Lu Y L, Brooks C R, Chen L J, etal. A technique for the removal of oxides from the fracture surfaces of alloy[J].Materials characterization,2005,54(2):149-155.), this electrolyte is generally used to remove grease and silicate scale on the fracture surface

[0004] Due to the corrosion of the environmental conditions of the special working conditions of the power plant (for example, humid atmosphere, corrosive gas / liquid environment, etc.) and the long service time, it is difficult to obtain timely protection for the fracture on site and rust occurs, so that the surface of the fractured fracture is usually covered with oxidation Products, corrosion products, and deposits. If such coverings are not cleaned properly, it will not be possible to obtain an objective and accurate electron microscopic appearance of the fracture.

However, the above-mentioned existing methods are not ideal for the fracture cleaning effect of superalloy parts with a long service time, or the oxides and corrosion products on the fracture surface cannot be removed and the fracture morphology cannot be revealed, or the local excessive cleaning leads to damage. Real fracture texture information

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