SU1602877A1 - Method of microalloying steel with titanium - Google Patents

Abstract

The invention relates to ferrous metallurgy, more specifically to methods for micro-alloying of steel. The purpose of the invention is to improve the quality without deterioration of weldability. In the production of steel after melt processing, the refining slag or refining mixture is injected with two portions of aluminum and ferrotitanium at a ratio of the total consumption of titanium to aluminum 1: (3-6). Aluminum and ferrotitanium in the first portion are introduced in an amount of 70-90% of the total consumption, and the second portion is introduced after the melt is aged. The melt is kept for 10-30 minutes, while in the first batch the aluminum is introduced before ferrotitanium, and the refining slag or refining mixture contains 2.5-5.0% of titanium dioxide. The application of the technology makes it possible to obtain steel hardened with titanium carbides, which in terms of strength properties, viscosity and weldability corresponds to steel hardened with niobium and vanadium carbides. 1 tab.

Description

This invention relates to ferrous metallurgy, in particular to methods for micro-alloying of steel.

The purpose of the invention is to improve the quality without deterioration of weldability.

Example 1. A smelting mass of 340 tons is produced in a casting ladle, into which 16 tons of lime-alumina slag, containing 2.5% of titanium dioxide, are previously introduced. In the process of melting, manganese and silicon-containing ferroalloys are introduced into it to deoxidize and alloy the metal. At the moment of filling the ladle with 1/2 of its volume, the first portion of aluminum (750 kg) and then 250 kg of titanium are introduced into the metal. Obshaya mass of the first portion of aluminum and

titanium is 1000 kg. The ratio of titanium to aluminum is 1: 3. At the end of the production, the metal bucket is transported to the after-treatment plant, where 10 minutes after the first titanium batch (in the form of ferrotitanium) is introduced, at the beginning of the metal purging process, a second batch is introduced with powdered silicocalcy: first 107.5 kg of titanium in the form of ferrotitanium then 322.5 kg of aluminum, only 430 kg. The mass ratio of titanium to aluminum is 1: 3, and the ratio is 1: 3. portions of titanium and aluminum make up 70% of the total mass of these materials consumed for smelting. The finished steel has the following chemical composition,%: carbon 0.11; silicon 0.30,

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manganese 1, 65; sulfur 0,003 ,. Phosphorus 0.020; aluminum 0.03, titanium 0.075. The steel is poured into blanks in a continuous casting process, which is rolled from a sheet with a thickness of 15.7 m. Samples are taken from the sheet to test the finished sheet. The impact strength of the near-weld zone of field tests is 65 J / cm. According to the results of tests of five-fold flat samples, the strength of steel is 635 N / mm.

Example 2. A filling of 340 tons mass is produced in a steel-teeming ladle into which 15 12 tons of lime-alumina slag containing 4.0% of titanium dioxide are previously introduced. Before the release of the smelting slag, a portion of aluminum weighing 340 kg is introduced. In the process of melting, 20 manganese and silicon-containing ferroalloys are introduced into it to deoxidize and alloy the metal. By the time the bucket is filled 1/2 of its volume, another 510 kg of aluminum is seated in the metal (shells of 25 ka of aluminum of 850 kg). At the end of the release, the ladle with the metal is transported to the installation of a batch vacuum. Neither, and in the beginning of the evacuation, 188 kg of titanium is introduced into the metal in the form of ferrozo titanium (first portion). The total weight in the first portion of aluminum and titanium is 1038 kg. The ratio of titanium and aluminum is 1: 4.5. 20 minutes after the introduction of the first portion in the process of vacuuming (after 15 cycles), a second portion of titanium and alumish is introduced: first 47.7 kg of titanium in the form of ferrotite, and then 214.3 kg of aluminum, only 262 kg. The weight ratio of titanium to 40 aluminum is 1: 4.5. The mass of the first portion of titanium and aluminum is 80% of the total mass of these materials consumed for smelting.

This steel has the following chemical composition,%: carbon 0.11, silicon 0.32, manganese 1.54, sulfur 0.004; (phosphorus; 0,018 aluminum OV06 i titanium 0.08, Steel is poured into billets at low-pressure cuts, which are rolled at 1 m modes on a sheet 16.7 mm thick. Samples are taken from the sheet to test the mechanical properties and conduct field tests The strength is 620 N / mm2. The impact viscosity of the heat-affected zone (CS) at -60 ° C is 60 J / cm. There are no cold cracks.

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PRI me R 3. A melt weighing 320 tons is released into a steel-teeming ladle into which 8.0 tons of lime-alumina baton containing 5.0% of titanium dioxide are previously introduced. In the smelting process, manganese and silicon-containing ferroalloys are introduced into the metal for deoxidation and alloying. At the moment of filling the ladle with 1/2 of its volume, the first portion of titanium and aluminum is introduced into the metal: first 900 kg of aluminum, and then 150 kg of titanium in the form of ferrotitanium. The total weight of the first serving is 1050 kg. The ratio of titanium to aluminum is 1: 6. At the end of the production, the metal bucket is transported to the out-of-furnace treatment plant. 30 minutes after the melt is released, the second portion of aluminum and titanium is introduced into the bucket during the metal purging with argon: first, 16.9 kg of titanium in the form of ferrotitanium, and then 101, 9 kg Alu-mi, only 118 kg. The weight ratio of titanium to aluminum is 1: 6. The mass of the first portion of titanium and aluminum is 90% of the total mass of these materials consumed for smelting. The finished steel has the following chemical composition,%: carbon 0.09; silicon 0,27; manganese 1.62; sulfur 0.006; phosphorus 0.02, aluminum 0.04; titanium 0.070. Steel is poured from the billet to the continuous casting machine, which is then rolled in controlled mode on a sheet of steel, another 15.7 mm. Samples are taken from the sheet to test the mechanical properties and conduct full-scale tests to evaluate the weldability. The strength of the steel according to the test results of five-fold flat samples is 610 N / mm. The impact strength of the heat-affected zone on Melanie samples at 75 J / cm. Cold cracking was not observed.

The results are shown in the table.

As can be seen from the table, a violation of the technical solution leads to a greater variation in the concentration of titanium (the required content is 0.07–0.09%) in the steel and, as a result, to the deviation of the mechanical properties of the steel from the specified requirements — low strength (no - less than 600 N / mm), insufficient viscosity of the heat-affected zone (less than

40 J / cm) - and the appearance of cold cracks in a welded joint.

The proposed titanium micro-alloying method allows, with high reliability, to obtain steel hardened with titanium carbides, which, in terms of strength, viscosity and weldability, fully complies with

titanium and aluminum, the exposure of the melt, characterized in that, in order to improve the quality of the B 5 deterioration in weldability, ferrotitin and aluminum are introduced to two margins after melt processing of refining slags or refining sew at a ratio of total consumption

OTBeTCTRvPT n ATTR The ratio of the total races

corresponds to steel, hardened carbo-10 titanium to aluminum 1: (3-6) with nitrosides mrnfiMcr mio., ™ ,, “vj oy, with

shubi and vanadium nitrides.

Claims (1)

The invention of the method of micro-alloying of steel with titanium, mainly high-strength hardened titanium carbides, including melt discharge into a ladle, treating the melt with refining slag or refined mixtures containing titanium oxides, introducing ferroethe with the first batch of ferrotitanium and mini enter in the amount of 70-90% of the total consumption, and the second portion after the melt aging, and   pa1; water, and Predominantly high strength, 15 I will endure duty 10; NNO KNAPYPYamm Ttjf ,,, - „on i j 20 30 minutes, aluminum in the first batch in d t before entering ferrotitanium, and refining slag or refining mixture contain 2.5-5.0% titanium dioxide. 776 titanium and aluminum, melt aging, characterized in that, in order to improve quality without deteriorating the weldability, ferrotitin and aluminum are introduced by two ports after refining the melt to refining slags or refining mixture at a ratio of total consumption P relation of total races titanium to aluminum 1: (3-6) that "vj oh, with titanium to aluminum 1: (3-6) that "vj oh, with This first portion of ferrotitanium and aluminum is introduced in the amount of 70-90% of the total consumption, and the second portion after melt aging, and pa1; melt, and Duration I will endure 10d Duration I will end up equal 10on i j 30 minutes, the aluminum in the first portion is introduced before the ferrotitanium is introduced, and the refining slag or refining mixture contains 2.5-5.0% of titanium dioxide. During the retreat from the declared regimes; Below are the specified requirements.