Stress corrosion cracking behavior of 20MnTiB high-strength bolts in simulation of humid climate in Chongqing

Abstract20MnTiB steel is the most widely used high-strength bolt material for steel structure bridges in China, and its performance is of great significance to the safe operation of bridges. Based on the investigation of the atmospheric environment in Chongqing in recent years, the corrosion solution to simulate the humid climate of Chongqing was designed in this study, and the stress corrosion experiment of high-strength bolts in the simulated humid climate of Chongqing was carried out. The effects of temperature, pH and concentration of simulated corrosion solution on the stress corrosion behavior of 20MnTiB high-strength bolts were studied.

Stress Corrosion Cracking Behavior of 20MnTiB High-Strength Bolts in Simulation of Humid Climate in Chongqing

20MnTiB steel is the most widely used high-strength bolt material for steel structure bridges in China, and its performance is of great significance to the safe operation of bridges. Based on the investigation of the atmospheric environment in Chongqing in recent years, the corrosion solution to simulate the humid climate of Chongqing was designed in this study, and the stress corrosion experiment of high-strength bolts in the simulated humid climate of Chongqing was carried out. The effects of temperature, pH and concentration of simulated corrosion solution on the stress corrosion behavior of 20MnTiB high-strength bolts were studied.

Quantification of dissolved organic14C-containing compounds by accelerator mass spectrometry in a corrosion experiment with irradiated steel

ABSTRACTLow- and intermediate-level (L/ILW) radioactive waste produced in Switzerland consists of large amounts of14C-containing irradiated steel.14C will be released during the anoxic corrosion of the steel in the cementitious near field of an L/ILW repository. In this study, a corrosion experiment with irradiated steel was carried out to determine the speciation of14C released during the corrosion process in conditions similar to those anticipated in the near field of a cement-based repository. The development of the experimental setup, including installation of the reactor and development of suitable analytical methods based on compound-specific14C analysis with accelerator mass spectrometry (CSRA AMS) is reported. Time-dependent increase in the total content of14C-bearing organic compounds in solution (TO14C) was determined by AMS and the main organic corrosion products that are14C-bearing formate, acetate and lactate were identified by CSRA AMS after a pre-concentration step. The concentration of the14C-bearing organic compounds was found to be very low (fmol to pmol14C/L). Stable carbon compounds were identified and quantified while the source of stable carbon in the system has not yet been identified and the temporal evolution of the concentration of these carbon species is presently not understood.

Early Monitoring of Rebar Corrosion Evolution Based on FBG Sensor

Cracks of structural members caused by rebar corrosion directly influence the service life of reinforced concrete structures. Therefore, it is important to monitor early corrosion evolution of the rebar and take the early steps to overcome the situation. In this paper, the response relationship between wavelength variation of Fiber Bragg grating (FBG) sensor and mass loss rate of the rebar is derived. The accuracy of the proposed theoretical model is verified by the electricity accelerated rebar corrosion experiment. It indicates that the theoretical model matches well with the tested value. Moreover, in this study, real-time online early monitoring of rebar corrosion evolution is built.

A knowledge-embedded lossless image compressing method for high-throughput corrosion experiment

High-throughput experiment refers to carry out a large number of tests and attain various characterizations in one experiment with highly integrated sample or facility, widely adopted in biology, medicine, and materials areas. Consequently, the storing and treating of data bring new challenges because of large amount of real-time data, especially high-resolution images. To improve the storing and treating efficiency of high-throughput image, a knowledge-embedded lossless image compressing method is proposed. Based on the similarity of a series of high-throughput images, it accomplishes the high compression ratio according to the difference between the target images and one reference image. Meanwhile, the knowledge extracted from the image, such as edge information and differences from the reference image, is recorded into the compressed file. The key steps include similarity comparison, edge detection, coordinate transformation, and dictionary encoding. The method has been successfully applied into high-throughput corrosion experiment facility, a typical intelligent cyber-physical system. To evaluate the performance, corrosion metal, face, and flower images are compressed by our method and other lossless image compression methods. The results show that our method has fairly high compression ratio. Moreover, the embedded knowledge can be read directly from the compressed file to support further study.