When welding high-alloy steels and alloys is difficult to ensure stability of the weld metal and metal heat-affected zone in the formation of cracks and corrosion resistance of welded joints, to preserve the properties of the weld metal and weld time under stress and high temperatures, getting tight joints. Technological features of welding high-alloy steels due to their physical properties. Reduced thermal conductivity and high electrical resistance (approximately 5 times greater than that of carbon steels) contribute to the higher rate of melting metal, a greater depth of penetration and deposition rate. Reduced thermal conductivity and high coefficient of linear expansion are responsible for enhanced buckling of structures by welding. Therefore, in the arc welding processes to produce modes with lower values of current and heat input power at smaller departures electrode greater speed of its delivery as compared with welding carbon steels. One of the main tasks of technology arc welding of high alloy steels and alloys is to ensure uniformity of chemical composition on the length of the seam and its cross section, which is achieved by maintaining strict consistency welding conditions. With the mechanized method is easier to ensure consistency of welding regime and the stability composition, structure and properties of the weld metal.
Therefore, in the manufacture of structures made of high alloy steels and alloys should strive to achieve maximum mechanization of welding processes. To prevent the intoxication of the alloying elements and protection from the interaction with the air additional requirements – welding in an inert environment, the use of coatings and fluxes, welding short arcs, provides the best results automatic welding. For welding high-alloy steels and alloys using manual metal arc welding with covered electrodes, manual, mechanized and automatic welding in protective gases, submerged arc welding, electroslag. Welding with covered electrodes operates at reduced compared with welding carbon steels currents, the dc reverse polarity, without transverse suture needles swing, short arc. Using basic coated electrodes with a rod of wire, appropriate brand welded steel with light indicator weldability and performance requirements. For example, when welding chromium-nickel steel to prevent the formation of hot! cracking and intergranular corrosion using electrodes such as E-04H20N9 (Brand CL-11) or E-02H19N9B (RLA-7), providing a weld austenitic-ferritic (2,5-7% ferrite). Submerged arc welding used to connect to a thickness of 3-50 mm. Compared with welding carbon steels to high alloy steels by 1,5-2 times reduced flight electrode, used electrodes with a diameter of 2-3 mm, welding, multi-layered, at a constant current of reversed polarity with fluxes (ANF-14, AN-26, etc.).
The big advantage of submerged arc welding in comparison with the manual, along with increased productivity and quality of connections is to reduce costs associated with the partitioned edges. Welding in protective gases is carried out in inert gases, consumable and consumable electrode is continuously burning and pulsed arcs. tig tungsten electrode is used for details of the thicknesses of less than 7 mm and for welding root passes. Welding consumable electrode operates in argon, as well as in mixtures of argon and helium is used and a mixture of argon and oxygen and carbon dioxide. Welding consumable electrode operates on the current strength, which provides inkjet transfer of the metal electrode.