Microstructure Refinement on Crevice Corrosion of High-Speed Rail Steel U75V Visualized by an In Situ Monitoring System

Rail foot covered by a fastener will suffer from crevice corrosion, leading to thinning and localized attack of crevice interior posing a risk of failure. This work investigated crevice corrosion behavior of a typical pearlitic high-speed rail steel U75V, focusing for the first time on the effect of pearlitic microstructure refinement achieved by heat treatment with different cooling rates 2, 5, and 10°C/s. Under anodic polarization, localized dissolved spots presented on the as-received sample, where crevice corrosion mostly initiated from. For cooling rates 2 and 5°C/s, localized dissolved spots were also observed but crevice corrosion was mostly presented as general corrosion instead of from local spots, ascribed to enhanced tendency of uniform dissolution due to microstructure refinement and homogenization. For cooling rate 10°C/s, crevice corrosion expanded flocculently, ascribed to preferential dissolution of pearlitic nodules with entangled cementite due to over refinement. Crevice corrosion was obviously accelerated by microstructure refinement. Cooling rates 5 and 10°C/s led to the fastest and slowest expansion of the corroded area, respectively, while the corrosion depth was just the opposite based on the same amount of metal loss. This work provides important information regarding the effect of pearlitic microstructure refinement on crevice corrosion and introduces a facile method for in situ monitoring of crevice corrosion.

Effect of Alloying Composition on Microstructure and Mechanical Properties of Ultranarrow Gap Welded Joints of U71Mn Rail Steel

A new welding method, ultranarrow gap welding with constrained arc by flux band, is proposed to compensate for the low quality of rail thermite welded joints. This article presents the results of research on the microstructure and mechanical properties of ultranarrow gap welded joints of U71Mn rail steel made using three types of alloying composition content flux bands. Results indicated that the base metal metallographic microstructure consisted mainly of pearlitic, the HAZ was mainly composed of fine pearlite, and the microstructure of the welded bead was composed of acicular ferrite, while the weld grain size decreased as the alloy composition increased. The average hardness noticeably changed in weld metal as the alloy composition increased, and when the alloy composition reached 19%, the hardness was equivalent to the base material. The average hardness value of the HAZ (35.8 HRC) was higher than that of the base metal (24.8 HRC). The tensile strength increased, and the percentage elongation after fracture decreased with increasing alloying composition from 9% to 19%. The impact absorbing energies were decreased as the alloying composition increased. Consequently, all the mechanical properties of rail ultranarrow gap welding were higher than those of the standard requirements of the rail flash welding. And the optimal alloying composition of flux band was 19%.

Bringing the Outside In

Chapter 2, Bringing the Outside In, examines the industrial infrastructures within which the burgeoning profession of public relations coalesced: rail, steel, and coal, and the simultaneous development of information infrastructures to situate these industries as paragons of democracy in the American imagination. It was in struggles over labor rights, workers’ rights, employee welfare, and industrial reform that the practice of public relations forged its methods, as scions of power and privilege attempted to manage the “external environment” of public and political opinion to reduce friction for the machinations of heavy industry. While the “external environment” does not directly map onto the natural environment, we see in these struggles the porousness of the boundaries between the inside and the outside of industrial production, allowing industrial leaders to control the outside world in addition to the one within their walls.

Corrosion performance of a corrosion-resistant rail steel in the simulated subsea tunnel environment

The corrosion performance of a newly developed corrosion-resistant rail steel (U68CuCr) was investigated and compared with that of a normally used high-speed rail steel (U71MnG) by neutral salt spray tests, electrochemical tests, X-ray diffraction analyses, and the scanning vibrating electrode technique. It was found that the weight loss and corrosion rate of U68CuCr were lower than those of U71MnG under the same corrosion conditions. In addition, due to the influence of alloying elements (copper and chromium) in U68CuCr, the rust layer was thicker and denser, resulting in a stronger protective effect. Moreover, U68CuCr had a higher corrosion potential in electrochemical tests. Finally, the dynamic corrosion process of U68CuCr in 2.2% NaCl solution mainly followed a lateral extension of corrosion. Therefore, the corrosion resistance of U68CuCr was better than that of U71MnG in the subsea tunnel environment.