CS215399B1 - Ceramic flux for automatic submerged arc welding - Google Patents

Abstract

The invention solves the problem of a suitable ceramic flux for automatic submerged arc welding of structural unalloyed and low-alloyed steels operating at sub-zero temperatures. The essence of the invention lies in the chemical composition of the flux, which consists of 7 to 14 mass % silicon dioxide, 0.2 to 10 mass % manganese dioxide, 24 to 38 mass % aluminum oxide, 12 to 24 mass % magnesium oxide, 0.1 to 3 mass % calcium oxide, 2 to 8 mass % sodium and potassium oxide together, 18 to 31 mass % calcium fluoride, the remainder being impurities of iron oxide, phosphorus and sulfur. It is advantageous if the ceramic flux according to the invention contains 0.1 to 5 mass % zirconium oxide.

Description

BACKGROUND OF THE INVENTION The present invention relates to ceramic fluxes for automatic submerged arc welding of structural unalloyed and low alloy steels, and in particular steels operating at minus temperatures.

Welding of steels operating at minus temperatures requires a favorable metallurgical effect of the flux on the molten metal in order to achieve the desired notch toughness of the weld metal.

By its metallurgical effect, flux has an effect on chemical composition, structure, content of inclusions, content of gases and impurities in the weld metal. It is important to achieve a structure which has very good toughness even at minus temperatures, as well as low inclusions, gases and impurities.

A fused acid type flux is known which contains 35 to 45 wt. % silica, 33 to 42 wt. % manganese oxide, 5 to 10 wt. % alumina, 4 to 10 wt. calcium oxide, 3 to 8 ° / ₀ wt. Calcium fluoride enhancing elements are magnesium oxide, sodium and potassium oxide and titanium dioxide.

With this flux I achieve! average notch toughness values at room temperature. The values of notch toughness are very low at minus temperatures. The flux does not have a favorable metallurgical effect on the weld metal composition, structure and purity.

Furthermore, it is known to melt the flux of the composition of 6-15 ° / ₍₎ wt. % silica, 1 to 7 wt. % manganese oxide, 36.7 to 47 wt. % alumina, 1 to 4 wt. % of magnesium oxide, 10 to 17 wt. % calcium oxide, 1 to 3 wt. sodium and potassium oxides together, 16 to 28% tang. % calcium fluoride, 1 to 8 wt. barium fluoride. With flux, good notch toughness is achieved at room temperature, but notch toughness rapidly decreases at minus temperatures. The flux has a better metallurgical effect on the weld metal than the previous flux.

The above-mentioned drawbacks are largely eliminated by the ceramic flux according to the invention, which comprises 7 to 14 wt. % of silica, 0.2 to 10 wt. % manganese oxide, 24-38 wt. % alumina, 12 to 24 wt. % of magnesium oxide, 0.1 to 3 wt. % calcium oxide, 2 to 8 wt. % of sodium and potassium oxides together, 18 to 31 wt. calcium fluoride oxide, the remainder being iron oxide, phosphorus and sulfur. To increase the beneficial effect, it is preferred that the flux comprises 0.1 to 5 wt. zirconium oxide.

When welding with the ceramic flux according to the invention, the arc burning is very stable with a very small variation in parameters, this is ensured by a sufficient content of ionizing sodium and potassium oxides. The caterpillar is evenly formed with a smooth surface. The slag removability is spontaneous even when welding in a narrow bevel. Ceramic flux also has a beneficial effect on the weld metal. It influences the favorable structure and purity of the weld metal.

The ceramic flux according to the invention consisting of 7.6 wt. % silica, 1.4 wt. manganese oxide,

24.8 wt. % alumina, 22.93 wt. of magnesium oxide, 1.3 wt. % calcium oxide, 7.4 wt. % of sodium and potassium oxides together 30.5 wt. % calcium fluoride, 3.1 wt. % zirconia, 0.9 wt. % of iron oxide, 0.04 wt. phosphorus and 0.03 wt% sulfur.

Weld metal made with the subject flux and wire having a composition of 0.09 wt. carbon, 1.09%. wt. % manganese, 0.1 wt. % silicon, 0.41 wt. Molybdenum achieved very good notch toughness values at +20 ° C 160 J / cm ² and at -70 ° C 80 J / cm ² .

With a flux of 13.2 wt. % of silica, 8.5 wt. % manganese oxide, 36.64 wt. % alumina, 14.7 wt. of magnesium oxide, 2.5 wt. % calcium oxide, 3.2 wt. % of sodium and potassium oxides together, 20.4 wt. % of calcium fluoride, 0.8 wt. % ferric oxide, 0.03 wt. % phosphorus and 0.035 wt. sulfur, also very good results were obtained, similar to the above example.

The ceramic flux according to the invention represents an improvement in comparison with the previous fused fluxes in terms of metallurgical effect on the weld metal and its very good plastic properties up to -70 ° C.

Claims (2)

OBJECT 1. A ceramic flux for the automatic welding of submerged fluxes of structural unalloyed and low alloy steels and, in particular, of low temperature steels, characterized in that it consists of 7 to 14% by weight. silica, 0.2 to 10 wt. manganese oxide, 24 to 38 wt. alumina, 12 to 24 wt. magnesium oxide, 0.1 to 3% by weight; % of calcium oxide, 2 to 8 wt. % sodium and potassium oxides together, 18 to 31 wt. calcium fluoride, the remainder being iron oxide, phosphorus, and sulfur impurities. 2. A ceramic flux according to claim 1, characterized in that it contains 0.1 to 5 wt. zirconium oxide. Tisk 51/84