Testing device for fatigue crack growth rate under seawater corrosive environment and measuring method for testing device

Abstract

The invention provides a testing device for fatigue crack growth rate under a seawater corrosive environment and a measuring method for the testing device. The testing device is characterized by comprising a three-point bending fixture and a seawater environment container tank, wherein the seawater environment container tank is connected with a circulating seawater supplying device positioned outside the seawater environment container tank. The testing device and the measuring method disclosed by the invention are suitable for measuring the fatigue crack growth rate of a single edge notch SE (B) sample; a conventional three-point bending fixture is inversely mounted, and a machining gap of the SE (B) sample and a compliance measurement COD (Crack Opening Displacement) gauge are enabled to be positioned above the sea level, so that the COD gauge can be measured by a compliance method and the condition that the COD gauge is corroded since the COD gauge is placed in seawater can be avoided; besides, by using an anti-splashing cover plate, the phenomenon that a fixture system and a fatigue testing machine are corroded due to seawater splashing during a fatigue test is prevented; the testing device has high practicality.

Description

technical field [0001] The invention belongs to the technical field of testing the mechanical properties of metal materials, and specifically refers to a fatigue crack growth rate testing device and a measuring method thereof in a seawater corrosion environment. Background technique [0002] The fatigue crack growth rate test is an important test to evaluate the fatigue performance of metal materials. In the seawater corrosion environment, the fatigue crack growth of the material will be accelerated, so the investigation of the fatigue crack growth rate of the material in the corrosion environment is more pertinent for the corrosion-resistant steel varieties. [0003] The national standard GB / T6398-2000 "Metallic Materials Fatigue Crack Growth Rate Test Method" appendix C introduces the test device under aqueous medium, but it is limited to the center crack M(T) specimen and the compact tension C(T) For the sample, there is no suitable test device for the unilateral notch S...

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Problems solved by technology

Invention patent CN202119748U "a test device for corrosion fatigue crack growth" designed a corrosion medium box suitable for the central crack M (T) sample, the box is stuck on the test section of the sample when the fatigue test and There is friction between the samples, and the sealing performance requirements are very strict. Once leaked, the corrosive medium will corrode the fatigue test equipment. In addition, the resistance sheet is used to test the crack growth. It needs to be calibrated before each test. It is better to use the COD gauge and use the flexibility method directly. Easy to measure

Invention patent application CN101358929A "An environmental device for fatigue crack growth rate test in a corrosive environment" also developed an environmental box stuck in the crack growth area on the surface of the sample. space, to prevent the COD gauge from being corroded by the corrosive medium, but this device is only suitable for compact tensile C(T) samples, and due to the small volume of the medium box, a small amount of corrosive medium may move up and down with the sample at high frequency in a small space. Heating causes changes in the stress field at the crack tip and affects the validity of the test results

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