SU840135A1 - Method of stainless steel production - Google Patents

Description

This invention relates to ferrous metallurgy, in particular to the development of stainless steel making. The closest to the proposed method is the crawling of stainless steel, which consists in melting the base metal in the furnace, preliminary deoxidation and alloying with ferrous metals, followed by the addition of aluminum, complex alloy and titanium, and its release into the ladle l. The disadvantage of the method lies in the fact that in stainless steels stabilized by titanium, needle-like inclusions of titanium carbosulfides form at the grain boundaries, reducing the ductility of steel. In addition, titanium is consumed with sulfur and does not fully contribute to the stabilization of carbon. In order to prevent the formation of titanium carbosulfides, the development of new methods for the deoxidation of steel aimed at the binding of sulfur in steel before it is combined with standard, for example, by introducing rare earth Hbix metals into steel, is required. The aim of the invention is to develop a method for producing stainless steel providing high ductility of the metal and increased toughness. This goal is achieved by the fact that rare-earth metals in the amount of 0.10-0.50 kg / ton of steel are introduced into the melt prior to the aluminum additive. Considering that further improvement in the quality of steel can be achieved as a result of complex aluminum deoxidation together with modifier elements capable of globularizing oxide-sulphide formations, rare-earth metals are used in the steelmaking as a globular inclusion. The distinctive ability of rare-earth metals is their high chemical affinity to most of the elements contained in steel, especially to harmful impurities, such as oxygen, sulfur, and nitrogen. The effect of rare earth metals is manifested in the reduction of the content of these impurities in steel and in their translation from active to passive forms. which largely facilitates the cleaning of grain boundaries. Formed inclusions (oxides, sulfides, nitrides) have a modifying effect on the steel structure. Example. In a 50 kg induction furnace, I test the proposed method for the production of steel grade X18H9T, the chemical composition of the steel (GOST 5632-61). wt.%: Carbon Not more than 0.12 Not more than 0.80 Silicon 1.0-2.0 Manganese Nickel 8.0-9.5 Up to 0.7 Iron Iron Rest Not more than 0.020 Phosphorus Not more than 0.035 To establish the effect rarely the grinding metals on the plastic properties and toughness of steel 54 is deoxidized according to 3 experimental variants, including the boundary values of the amount of rare-earth metals. In the 4th embodiment, the steel is deoxidized according to a known method. Comparative data of the deacidification are presented in Table. For each of the options held on 3 swimming trunks. Mechanical properties are determined by testing thermally treated samples (quenching and cooling in water). The test results are shown in Table 2. The advantage of deoxidation according to the inventive method is to increase the relative elongation by an average of 28.5% of the relative narrowing by an average of 27.6%, and the impact strength by an average of 20.0%. All o.pryatnye variants of the proposed method have an advantage over the known, however, the complex of the obtained indicators preference should be given to 2 variants of deacidification, providing for the sequential introduction into the furnace, kg / t: rare earth metals 0.3, aluminum 1.25, complex alloy 5.0 and titanium 12. Table 1

50 56

25 22 23 21

58 56 55 53

57 42

table 2

13.1 14.5 14.4 11.6

5 840135

Claims (1)

The claims of the invention and the impact strength of the metal, in the decomposition of the ... before the addition of aluminum, are introduced the redposit of the preparation of stainless hundred-gram-earth metals in the amount of whether, including melting, pre-, p "g, /-ha, t" smooth deoxidation and doping ferroalloys with the subsequent prisad- Sources of information Coal Aluminum, complex alloy is taken into account during the examination and titanium, and the release of the bucket, about t l and-1. USSR author's certificate with the fact that, with the purpose of application number 2649739 / 22-02, C 21 C 5/52 increase plastic characteristics1978. and 1 U kg / t CTaJIri ".