OPEN ACCESS
The technological development, and the mastery of the obtaining of steel of good mechanical and structural quality contributed to the realization of the installations and structures, based on steel, of very high performances in particular on the mechanical level resistance to corrosion and others ... etc. Welding steels has a lot of advantage in the industry and the shaping of the installations. But it also has disadvantages and weak points, which round the assembly vulnerable The fused area of the weld and the heat affected zone HAZ, do not have the same structural characteristics and mechanical characteristics comparable to the base métal zone.
The search for the fragility and safety of steels, a the search for the fragility and safety of steel has led to the appearance on the market of a relatively large number of steels for the manufacture of large diameter pipes. The main concerns with the introduction of alloying elements into steels are related to the increase in mechanical characteristics (elastic resistance Er, maximum resistance Mr), the easiest material implementation possible (welding) and severe conditions of use (high operating pressure, corrosive environment) [1].
Ferrite-hardening additive elements are distinguished. The most effective elements are those that we try to reduce for reasons of weldability(carbon) or improvement of the resilience characteristics (phosphorus, carbon, ... etc).
One of the methods of obtaining a combination of high strength, good ductility and weldability of steels is the refinement of ferritic grain.