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 particularly relates to a low-hydrogen type downward welding electrode. Background technique: [0002] With the development of oil and natural gas pipeline construction in my country in recent years, downward welding technology has been rapidly promoted and applied, especially in the annular weld welding of pipelines or pressure vessels. figure 1 As shown in the upside welding figure 2 As shown, the efficiency is improved by more than 30%, and the electrode consumption is reduced by 30% to 50%. However, the downward welding process puts high requirements on the all-position welding operability of the electrode itself: in the horizontal, vertical, and upward welding positions, the molten pool must always be kept clear and no slag drips; the welding arc must have a proper arc blowing Strength to help weld formation. [0003] The welding of large-diameter, high-strength, and large-wall-th...

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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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