CS243711B1 - Method of processing of strips of chromium steel β with higher strength - Google Patents

Abstract

The invention relates to the processing of cold-rolled strips of chromium steels with higher strength and corrosion resistance. Strips of steels with a mass composition of up to 0.80% silicon, up to 0.90% manganese, 0.17 to 1.05% carbon, 12 to 23% iron, up to 0.040% phosphorus, up to 0.035% sulfur are annealed at a temperature of 690 to 930 °C, pickled in a salt and then acid bath, after which they are rolled with a deformation of up to 80%, or else annealed again at a temperature of 690 to 850 °C and reduced by 8 to 80% by rolling to the final thickness and cut lengthwise.

Description

(54)

Method of processing strips of chromium steel β with higher strength

The present invention relates to the processing of cold-rolled strips of chromium pellets of higher strength and corrosion resistance.

Steel strips of a mass composition up to 0,80% silicon up to 0,90% manganese,

0.17 to 1.05% carbon, 12 to 23% overwhelming, to 0.040% phosphorus, to 0.035% sulfur, are annealed at 690 to 930 ° C, pickled in a salt bath and then acid bath, then rolled with deformation up to 80%, optionally annealed at a temperature of 690 to 850 ° C and reduced by 8 to 80% by rolling to final thickness and cut longitudinally.

243 711

243 711

The invention relates to a process for the treatment of cold-rolled strips of chromium steels in which higher strength and corrosion resistance are required.

Hitherto known methods of cold rolling mills consist in that steel strips having a carbon composition of 0.50 to 1.40% by weight of manganese 0.20 to 1.20%, silicon by 10 to 0.50%, and 6.60%, nickel up to 0.40%, sulfur up to 0.035% »phosphorus up to 0.035% are pickled, annealed, cold rolled, annealed, cold rolled or annealed, respectively. longitudinally cut, hardening and tempering.

The strips thus treated have a tensile strength of 1000 to 1700 MPa, are not resistant to chemical effects, are not resistant to corrosion, are not resistant to abrasion, and therefore have a long service life.

The above drawbacks are overcome by the method of processing the steel strips according to the invention.

The principle of the invention consists in that the strips of β steel with a weight composition of carbon 0.07 to 1.05%, manganese up to 0.90%, silicon up to 0.80%, almost 12 to 23% phosphorus up to 0.040%, sulfur up to 0.035% and are annealed at 690 to 930 ° C, pickled in a salt bath and then in an acid bath, then rolled up to 80% deformation, optionally annealed at 690 to 850 ° 0 and reduced by 8 to 80 by rolling to a final thickness, optionally cut lengthwise. After the second annealing, the strips can either be cut longitudinally and then reduced by 8 to 80% by rolling to a final thickness, or the strips can be reduced by rolling by 8 to 80% to a final batter and then cut longitudinally to the required width.

This method of processing, i.e. rolling by up to 80% hardening, achieves a tensile strength of up to 1300 MPa and further strengths of 2,243,711 and achieves other desired properties such as flatness, straightness, thickness and width tolerances.

A specific process for cold strip rolling from a starting thickness of 3 mm to a final thickness of 0.50 mm and a starting width of 310 nm to a final width of 90 mm was carried out on steel with a mass composition of 0.09% carbon · manganese 0.50%, silicon 0.40%, phosphorus 0.017 hitting & 0.015% »chrome 17 / <> ·

After annealing at 830 ° C for 2 hours · the strips were continuously pickled in a salt bath for 5 min · - sodium hydroxide, nitrate, borax · Continuous measurements in the bath followed by hydrofluoric acid 4 * nitric + sulfuric 4- water, 3 min · Continuous rinsing with hot water and brushing with rotary brushes followed. Bench mill with working cylinder diameter 160 mm, removals from initial thickness 3 mm to thickness 1.80 mm, annealing at 830 ° C in continuous furnace with non-neutral atmosphere of 75% hydrogen and 15% nitrogen with temperature 3 «In. Rolling mill with a working roll diameter of 160 mm to a thickness of 0.80 mm, annealing in a continuous furnace at a temperature of 830 ° G with a neutral atmosphere with a holding time of 3 min ·, rolling to a thickness of 0.51 mm, 3) work rolls to a final contract thickness of 0.50 mm and longitudinal cutting to a width of 90 mm ·

Examples of other processing methods are determined by the required dimensions of the finished belt and other qualitative features of the belt. They are also conditioned by the production equipment used. Other types of rolling mills can be used with different diameters and shapes of working rolls and hence other reductions. Other methods of treatment are possible provided that during the rolling from the last annealing to the contract thickness, a reinforcement corresponding to the chemical composition of the steel used and other agreed final strengths is achieved.

The strips treated in this way can be used for the production of cutting tools, in particular kitchen scraper and rotary knives, in particular for food processing robots, for the production of conveyors, in particular for the vulcanization process. furnaces and wherever it is necessary to increase. steel strength and increase corrosion resistance even at working temperatures up to 300C.

Claims (2)

SUBJECT OF THE INVENTION 243 711 A method of treating high strength chromium steel strips for the production of cutting tools, characterized in that steel strips having a carbon weight reduction of 0.07 to 1.05% »of manganese up to 0.90% _{t of} silicon up to 0.80%, chromium 12 to 23% »phosphorus up to 0,040%, sulfur up to 0,035% are annealed at 690 to 930 ° G, pickled in a salt bath and then in an acid bath, then rolled and deformed up to 80%, possibly annealed again at a temperature of 690 to 850 ° C and reduced by 8 to 80% by rolling to a final thickness and cut longitudinally. Method according to claim 1, characterized in that after the second annealing the strips are reduced by rolling by 8 to 80% to the final thickness and then cut longitudinally.