Method for preparing low hydrogen type downwards electrode

Abstract

The invention discloses a process for preparing hydrogen-controlled downwards electrodes. Steel wires H08E are used as a welding core, and explosive cartridge weight is 35-50% of the welding electrode weight. The percentage by weight of the invention is that CaCO3 is 25-38%, TiO2 is 10-20%, CaF2 is 12-20%, SiO2 is 5-10%, and Al2O3 is 3-6%. 8-15% ferrous alloy and 10-18% pure metal powder are added to meet the demand of the deposited metal rigidity and low-temperature flexibility. The electrodes have outstanding downward technology operational property, the welding positions, including flat, vertical and backstroke and the like, keep a metallic molten pool to be clean, and molten slag can not drip. The tensile strength of the weld metal is equal or more than 550 MPa, the ballistic work under the low-temperature of below 20 DEC G is more than 100 J, and the diffusible hydrogen content is less than 5 ml per 100 grams. The invention is adaptable for the welding of X42-X65 of API standard or other tube steel with equal rigidity grade, and is also suitable for the integral-position welding of pressure containers, ships, engineering machinery or other important structures, and the like.

Description

Technical field: [0001] The invention belongs to the technical field of welding materials, and in particular relates to a method for preparing a low-hydrogen downward electrode. Background technique: [0002] With the development of my country's oil and natural gas pipeline construction in recent years, downward welding technology has been rapidly promoted and applied, especially in the welding of circular welds in pipelines or pressure vessels, downward welding such as figure 1 Comparing upward soldering as shown figure 2 As shown, the efficiency is increased by more than 30%, and the consumption of welding rods is reduced by 30% to 50%. However, the downward welding process puts forward high requirements on the all-position welding operability of the electrode itself: in the flat, vertical, and supine welding positions, the molten pool should always be kept clear and the slag should not flow; the welding arc should have a proper arc blowing. force to help shape the weld...

AI Technical Summary

Problems solved by technology

[0003] The welding of large-diameter, high-strength, and large-wall-thick pipes or containers also puts forward higher requirements for the low-temperature toughness and crack resistance of the weld metal. Low-hydrogen electrodes are often used for welding under these conditions, but traditional Due to the characteristics of the slag of the electrode, the low-hydrogen electrode can only be welded by the upward welding method. When it is used for downward welding, the slag flows down and it is difficult to weld.

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