High Alloy Steels

Welding of medium-and high-alloy steels is difficult for the following reasons: during the welding process is a partial burning of dopants and carbon due to the low thermal conductivity may overheat welded metal, reinforced by the emergence of a tendency to hardening of structures, greater than that of low-carbon, linear expansion coefficient can cause significant stress and strain associated with heat the influence of the arc. The more dopants in carbon steel, the stronger the effect of these properties. To eliminate their influence on the quality of welded joints is recommended the following process steps:-meticulously prepare the product for welding, welding carried out at high speeds with little heat input to avoid overheating the metal – to prevent the reduction of internal stresses and the formation of hardening structures use heat treatment;-use of weld metal alloying electrode wire through the coating and to fill the burnable impurities in the welding process. Welding is done with direct current feedback polarity. At the same welding current is selected for 25 … 40 A to 1 m diameter electrode. The arc length may be short.

In industry and construction extensively used medium-and high-alloy steels: manganese, chromium, chromium-nickel, molybdenum and chromium steels, etc. belong to the group of stainless acid-proof and corrosion-resistant steel. The chromium content they share on srednelegirovannye (up to 14% Cr) and heavily doped (14 … 30% Cr). During welding of chromium steels having the following difficulties. Chromium at 600 … 900 C readily reacts with carbon to form carbides, which are situated in the thickness of the metal, speed intergranular corrosion, minimizing the mechanical properties of steel.

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