CS217684B1 - Ceramic flux for welding with austenitic strip electrode and welding of stainless steels - Google Patents

Abstract

Ceramic flux for welding with austenitic strip electrode and welding of stainless steels. The invention relates to engineering technology. The invention solves the problem of a suitable ceramic flux for welding with an austenitic strip electrode and welding of stainless steels, in particular its improved technological as well as metallurgical properties while increasing labor productivity. The essence of the invention consists in the chemical composition of the flux, which consists of 19 to 29% by weight of silica, 0.1 to 3% by weight of manganese oxide, 24 to 37% by weight of alumina, 5 to 15% by weight of magnesium oxide, 1 to 9% by weight of alumina. calcium oxide, 6 to 10% by weight sodium and potassium oxides together, 15 to 25% by weight calcium fluoride, the remainder being impurities, iron oxide from 0.01 to 1% by weight, phosphorus from 0.01 to 0.04% by weight, sulfur from 0.01 to 0.04% by weight.

Description

The invention relates to a ceramic flux for welding with austenitic chromium nickel strip electrode containing niobium, stainless layers on alloyed or low-alloy structural steels and for welding stainless steels.

In the strip electrode welding process below the flux, the flux has a decisive influence on the formation of the bead, the slag removability and the chemical composition of the deposit. Good bead formation and good removability are essential to achieve a perfect build-up. The tendency of slag baking increases mainly when welding with a niobium-containing chrome-nickel ribbon electrode. There are fluxes which have good slag removability when welded with austenitic chrome-nickel tape, but using chromium-nickel tape containing niobium will greatly impair the removability of slag from the surface of the deposit. The slag is either adhered to a large flat or a small flat in the form of fine needles. The unfavorable metallurgical effect of the flux is reflected in the chemical composition of the deposit, namely in the burn of chromium, niobium and silicon alloying. Depending on the chromium and niobium content, the corrosion resistance of the weld deposit depends on the burn-up of these elements. A silicon content above 1% by weight increases the susceptibility to hot cracking.

A fused flux having the following chemical composition is known: 28 to 38 wt. % silica, 15 to 29 wt. alumina, 5 to 13 wt.% calcium oxide, 10 to 18 wt. % of calcium fluoride, 17 to 30% magnesium oxide, 0.2 to 2.5% wt. % of sodium and potassium oxides together, 0.8 to 8 wt. % barium oxide, 1 to 6 wt. manganese oxide. This flux has essentially good molding bands due to the high silica content, which in turn adversely affects chromium burn, niobium and silicon deposition in the deposit, thereby reducing corrosion resistance and increasing the susceptibility to hot cracking.

Further, a fused flux having the following composition is known:

up to 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. % of sodium and potassium oxides in total 16 to 26 wt. % calcium fluoride, 1 to 8 wt. barium fluoride.

This fused flux has worse molding properties than the previous flux. The caterpillar is bumpy and staggered in the middle. When welding with a niobium band electrode, slag baking occurs on the bead surface. However, the flux gives low chromium and niobium burns and low silicon deposition in the weld deposit.

These drawbacks are largely eliminated by the ceramic flux for welding with an austenitic ribbon electrode and welding stainless steels according to the invention, which consists of 19 to 29% by weight. % silica, 0.1 to 3 wt. % manganese oxide, 24 to 37 wt. % alumina, 5 to 15 wt. % magnesium oxide, 1-9 wt. % of calcium oxide, 6 to 16 wt. % of sodium and potassium oxide, together 15 to 25 wt. calcium fluoride, the remainder being impurities iron oxide, phosphorus and sulfur.

When welding with a flux band electrode according to the invention, the arc burning with very low variation in parameters is very stable, this is ensured by a sufficient content of ionizing sodium and potassium oxides. Steady arc burning favorably affects the uniformity of the vapor. The bead is uniformly formed with a smooth surface, due to the favorable silica content, the slag removability is spontaneous even when welding with a niobium-containing electrode. The consumption of flux is very low about 0.5 kg of flux per kg of weld metal. Good slag formation and removability was achieved by the optimum combination of alumina, magnesium and silica, with alumina with a melting point of 2050 ° C and magnesium with a melting point of 2800 ° C, achieving a relatively high melting point and a thin layer of molten slag.

The ceramic flux according to the invention also has a favorable metallurgical effect on the chemical composition of the deposit, characterized by low chromium and niobium burns and low silicon alloying.

The ceramic flux according to the invention consisting of 20.5 wt. % of silica, 0.4 wt. manganese oxide, 27.9 wt. alumina, 14.3 wt. magnesium oxide, 8.1 wt. % calcium oxide, 13.7 wt. % of sodium and potassium oxides together, 15.0 wt. % of calcium fluoride, the remainder being impurities, 0.65 wt. % ferric oxide, 0.03 wt. % phosphorus, 0.030 wt. sulfur.

A weld deposit made using this ceramic flux and with an austenitic band electrode of 23.95 wt. % chromium, 11.50 wt. % nickel, 0.90 wt. % niobium, 0.29 wt. Silicon had a very good molded caterpillar with a smooth surface and smooth transitions between caterpillars, the slag separated spontaneously. A favorable metallurgical effect was also obtained, the chromium content in the surfacing was 22.46 wt%, the niobium content 0.81 wt%, the silicon content 0.58 wt%.

With a flux of 28.1 wt. % of silica, 2.6 wt. % manganese oxide, 34.5 wt. aluminum oxide,

6.8 wt. % magnesium oxide, 4.5 wt. % of calcium oxide, 6.5 wt. % of sodium and potassium oxides in total 16.2 wt. % of calcium fluoride, the remainder being impurities of 0.8 wt. iron oxide,

Claims (3)

Ceramic flux for welding with an austenitic band electrode and welding stainless steels, characterized in that it consists of 19 to 29 wt. % silica, 0.1 to 3 wt. % manganese oxide, 24 to 37 wt. aluminum oxide, 5 to 15 wt. Magnesium oxide, 1 to 0.035 wt. % phosphorus, 0.028 wt. Also, very good forming properties and a favorable metallurgical effect of the flux on the composition of the deposit have been achieved. INVENTION 9 wt. % of calcium oxide, 6 to 16 wt. % of sodium and potassium oxides together, 15 to 25 wt. % of calcium fluoride, the remainder being impurities of iron oxide from 0.01 to 1 wt. phosphorus from 0.01 to 0.04 wt%; sulfur from 0.01 to 0.04 wt%;