الفهرس 
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Abstract
Weathering steel is a high strength low alloy steel that in suitable environments forms an adherent protective rust ‘patina’ to prevent continuous oxidation . The corrosion rate is so slow that structures fabricated from unpainted weathering steel can achieve a 120 year design life with only nominal maintenance. Hence, weathering steel structures in an appropriate environment can provide an attractive, very low maintenance, and economic solution in many locations.
Weathering steel or Weather resistant (WR) steels are terms used to describe structural steels with improved atmospheric corrosion resistance. These steels are high strength low alloy steels , that under normal atmospheric conditions give an enhanced resistance to rusting compared with that of ordinary carbon manganese steels .
In the presence of moisture and air, all low alloy steels have a tendency to rust, the rate of which depends on the access of oxygen, moisture and atmospheric contaminants to the metal surface. As the process progresses, the rust layer forms a barrier to the ingress of oxygen, moisture and contaminants, and the rate of rusting slows down. The rust layers formed on most conventional structural steels ditch from the metal surface after a critical time, and the corrosion cycle commences again. Hence, the rusting rate progresses as series of incremental curves approximating to a straight line, the slope of which depends on the aggressiveness of the environment. With weathering steel, the rusting process is initiated in the same way, but the specific alloying elements in the steel produce a stable rust layer that adheres to the base metal, and is much less porous. This rust “patina” develops under conditions of alternate wetting and drying to produce a protective barrier, which impedes further access of oxygen and moisture.
Weathering steel structures, taking advantage of the latest advances in automated fabrication and construction techniques, are able to provide economic solutions to the demands of safety , rapid construction , attractive appearance , shallow construction depth , minimal maintenance , and flexibility in future use.
The mechanical properties of weathering steel depend on which and how thick the materials is.
In general weathering steels contains small amounts of Copper, Phosphate, Chromium, Nickel and Silicon to attain their weathering properties.
Aim of work:
The aim of this work is to develop weathering steel grade with excellent mechanical properties in addition to better weathering resistance properties suitable for bridges and sub ground vichels.
Plan of Work:
Primary materials proportion (steel grades processing)
- Two grades were proposed to the processed melting and casting in Y- blocks. The first one is containing Cr, Cu, and Ni without P. The second grade contains the same previous alloying elements but with different contents of P. The carbon content is 0.0631: 0.075 %.
- The Y- blocks are subjected to extensive investigations; e.g. microstructure, hardness, tensile and impact testing.
-Hardening by quenching followed by tempering was proposed for a second phase creation to enhance the mechanical properties.
-Weathering resistance was planed to be calculated and measured.
-SEM Fractography was proposed to the fractured impact specimens.