ANALYSIS OF STRESS CORROSION CRACKING OF HETEROGENEOUS WELDED JOINTS IN SIMULATED PRIMARY WATER ENVIRONMENT

Abstract

The paper deals with the stress corrosion cracking of heterogeneous welded joints. The welded joints were made of austenitic base metal (AISI 321) and ferritic weld metal by arc welding. Two methods were used to analyze the stress corrosion cracking of samples of this type of welded joint. The first method was a slow strain rate test (SSRT) using a tabletop device at a temperature of 60°C with a graded strain rate for three specimens (10−5 , 10−6 , and 10−7 1/s). The second method was exposure in a corrosion autoclave at a temperature of 270°C and pressure of 12.26 N/mm2 , while prestressing devices were used to achieve the prestressing at the level of yield strength and 3% plastic deformation. One specimen was bent to 60°. Boric acid solutions were used as the medium, which was supposed to simulate the environment of the primary circuit of nuclear power plants, a type of water-water energetic reactor. The surface and the presence of corrosion products, cracks, fractures, or pits on specimens were monitored using scanning electron microscopy, stereomicroscopy, confocal microscopy, and light microscopy. A gravimetric analysis was performed, as well, to determine the corrosion rate after exposure to the autoclave.

Keywords

• stress corrosion cracking
• welded joints
• autoclave
• corrosion
• primary water