SU1479535A1 - Method of producing strips of corrosion-proof steels of austenite class - Google Patents

Abstract

The invention relates to metallurgy and can be used in the production of strip of corrosion-resistant titanium-containing steels of austenitic class. The purpose of the invention is to increase the resistance in corrosive environments by reducing the tendency of steel to intergranular corrosion. A strip with a rolling end temperature of 920 ... 1050 ° C is cooled at a regulated rate of 14 ... 23 ° C / s to 730 ... 850 ° C. 1 tab.

Description

The invention relates to metallurgy and can be used in the production of strip of corrosion-resistant titanium-containing steels of austenitic class.

The purpose of the invention is to increase the resistance in corrosive environments by reducing the tendency of steel to intercrystalline corrosion.

Example. With a cross section of 200-1060 mm of corrosion-resistant steel grade 12X18H10T austenitic class containing,%: carbon 0.09; chrome 18; nickel 10; silicon 0, 7; manganese 1.4 and titanium 0.36 are heated in a furnace for 3.5 hours to 1 1250 C.

Another heated slab is pushed out on the 2000 hot rolling mill on a continuous broadband mill furnace and is compressed in a rough group to an intermediate thickness of 36 mm. The temperature of the metal after rolling in the rough train group is 1100 ° C. Then the roll is set into a continuous 7-cell finishing stand group, where it is compressed to a final thickness of 5.5 mm. The temperature of the rolling end Tkn 985 C is kept constant along the entire length of the strip by using an interstand cooling system.

The rolling strip is transported along a lateral rolling table of the mill 2000 with simultaneous cooling at a speed of 18.5 deg / s. After the strip is cooled at a regulated rate of 18.5 degrees / s to 790 ° C, it is wound into a roll, and the strip is subsequently cooled at an arbitrary rate.

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Cooling from 985 to 790 ° C at a rate of 18.5 degrees / s ensures a uniform structure with M2iC $ carbides along grain boundaries of a coagulated shape, uniform distribution of chromium throughout the grain volume and elimination of chromium depletion along the grain boundaries.

Samples are taken from the rolling strip, which are thermally treated and are prone to ICC in accordance with GOST 6032-82. After bending the flat sample on 90 in a vice with a 10 mm radius of the sponge and making it Z-shaped, the surface is monitored. There are no cracks on both bends, which indicates the absence of the tendency of corrosion-resistant steel of austenitic class to IHC.

The embodiments of the method and the results of tests of steel for inclination to ICC are given in the table.

As follows from the table, when implementing the method with the proposed technological parameters (examples 4-12), the steel has a minimum propensity for ICC as compared with the treatment beyond the limits of the proposed method (examples 1-13 and 14).

Claims (1)

Invention Formula The method of production of strips of corrosion-resistant austenitic steels, including hot rolling with a rolling end temperature of 920-1050 ° C, preliminary cooling at a regulated rate, and final cooling to ambient temperature, characterized in that in order to increase durability in aggressive media by reducing the tendency of steel to intergranular corrosion, pre-cooling is carried out at a rate of 14-23 degrees / s to 730-850 S. Examples 1-3 of the prototype. Editor T. Lazorenko Compiled by A. Stadnikov Tehred L. Serdkzhova Proofreader M. Vasilyeva