CS272968B1 - Method of metallized sheet-iron strips treatment made of low-carbon welding steels - Google Patents

Abstract

A method of treating coated sheet metal strips of low-carbon welding steel designed for the automobile industry or profile warping while hot with cold rolling, pyrogenic treatment of zinc or its alloys, inclusive of alloys of zinc with aluminium with additives, based on the fact that the rolls of coated sheet metal strips are diffusively annealed in bell furnaces at 200 to 535 degrees C and then they are lightly rolled with reduction of 0.4 to 1.5 %. With this method of processing the sheet metal strips are preferably rolled while cold to a coarseness of Re=0.04 to 1.0 micrometers and they are coated with zinc with rising coarseness of 40 to 80 g.m<-2> on one side, or 80 to 160 g.m<-2> on both sides. Diffusion annealing occurs during 2.5 to 3.5 hours operation at the selected temperature and with retardation for another 9.0 to 10.5 hours.

Description

Method of processing metallized low carbon steel sheet steel strips (^ 7) Treatment of metallized low carbon steel sheet metal sheets intended for the automotive industry or bent profiles after hot and cold rolling, hot dip galvanizing or zinc alloys, including zinc, aluminum alloy consists in that the coils of the metallized strips e and diffuse anneal in the hinged pans at a temperature of 200 to 535 ° C and are then easily rolled with a removal of 0.4 to 1.5%. In this treatment, the webs are preferably cold rolled to a roughness of 0.04 to 1.0 microns and are zinc coated with an output thickness of 40 to 80 gm on one side or 80 to 160 gm ^on both sides.

Diffusion annealing takes place at 2.5 to 2.5

3.5 hour rise to the selected temperature and with a hold time of another 9.0 to

10.5 hours.

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CS 272968 Bl

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for sputtering metallized strips of sheet metal, in particular to the automotive industry and to bent general purpose profiles of low-carbon weldable steels or low-alloy or cold-rolled steels. reducing the weight of the plating coatings and increasing their mutual adhesion.

For the mentioned purposes of using sheet metal, for example for bent profiles, and in particular for car bodies and exhausts in the automotive industry, low carbon deep-drawing or cold-rolled structural steels are used. These steels, in addition to the disadvantageous mechanical properties, exhibit insufficient corrosion resistance to atmospheric influences and, in particular, to impart thermal effects to, for example, car exhausts. Even in the case of the necessary plating for these purposes, it is necessary to apply coatings with a higher weight of about 275 g.m, on both sides, with relatively high surface roughness after cold rolling. Unsuitable structure of materials, especially on the surface of sheets in the so-called. the intermetallic phase, while not allowing the necessary adhesion and binding of the metallization coating to the sheet surface. These classic steels, with their unsuitable strength properties! and without an opaque surface and heat treatment before or after plating of the sheets, the relatively large depths of the sheets require high-weight products as well as difficult welding of the sheets so coated. The problem is partially solved by the development of materials with micro-alloying or low-alloying of low-carbon steels and their pre-plating technology. Galvanized strips have not already been heat-treated, or such heat treatment has been either for other purposes or failed, and in particular low or microalloyed steels show improved pre-treatment parameters, e.g. In the reduced need for roughening and better adhesion of the coatings, and the resulting corrosion resistance of the sheet without subsequent thermal treatment after plating, there remain difficulties with the resistance to mecbanic, thermal and atmospheric erosion of the coatings themselves, hence subsequent corrosion resistance and the necessary mechanical properties.

The above-mentioned drawbacks are overcome and the problem is solved by the method of sputtering metal-plated sheets of low-carbon weldable steels of the type of composition and in the divorced pretreatment according to the invention. The process according to the invention relates to said steels with a basic composition based on carbon up to 0.06% by weight, further manganese, silicon and aluminum, which are optionally low-alloyed with raolybdenum, titanium and zonone in a steel fraction of up to 0.55% by weight. or, optionally, micro-alloyed with vanadium, nitrogen, titanium and zirconium in total proportions of up to 0,40% w / w. and which are pre-treated by hot rolling after heating to 1220 to 1280 ° C and at a rolling temperature to 820 to 880 ° C to a thickness of 1,8 to 4,0 mm, and further cold rolled to a roughness Re of 0,4 until

1.0 microns and are finally zinc plated, eventually its alloys with regulator ··?

The coating thickness of the coating is 40 to 80 g.m. on one side plating, or 80 to 16 g.m. on both sides. The principle of the invention consists in that the coiled coils of the coated metal strips are diffusion annealed in the heater ovens at a temperature of 200 to 535 ° C with a 2.5 to 3.5 hour rise to the selected temperature and a holding time of a further 9.0 to 10 , 5 hours, on So sb paw rolled with a removal of 0.4 to

1.5%.

The advantages of the method according to the invention are mainly that all types of steels, i. Classical low-carbon, but also micro- or low-alloy, will improve the mechanical properties of metallized strips, in particular slip and elongation, coating resistance to surface thermal and atmospheric erosion and mecbanic abrasion and ultimately corrosion resistance of sheet metal products on both sides . Even with the use of alloyed low carbon steels, the roughness requirements of the rolled sheet prior to plating are substantially reduced, thereby reducing the manufacturing cost of the metallized sheets, including the possibility of annealing technology annealing on discontinuous equipment.

CS 272968 Bl

Examples of the invention;

1, Used low carbon steel used in gates with a content in% by weight, 0.04% C,

0.33% Mn, 0.13% Si, 0.015% S, 0.021% P and 0.043% Al were prepared by hot rolling after preheating to 1270 ° C, at a rolling temperature of 860 ° C and a coiling temperature of 660 ° C. , further cold rolling at 4-stools tandem on the final surface roughness / Re / »1.0 micrometer band and eventually refine both sides" of _the

Claims (3)

continuously glow in a zinc bath and coating 120 g.m. After winding, the coils were diffusion annealed in a lid furnace at a 3-hour ramp to 450 ° C and held at that temperature for 10 hours. Finally, the strip was easily rolled with a removal of 1.0%. Mechanical properties achieved: yield strength (Rn) &gt; 185 MPa, strength limit / Rm / and 325 MPa and Severity ´ / A 80 / n39%. Achieved values of corrosion resistance by tests according to industry standard for automotive industry / ONA no. 301011, respectively. The Steinslag test / were for all samples in Stage 1, which is 2 to 3 degrees better than comparable samples of black plate, annealed for other purpose and metallized single-sided, but also low-carbon, hot and electrolytically metallized and subsequently unused. According to the visual test for mechanical abrasion resistance of coatings coated after plating, the samples showed a 2-fold resistance, 2. Low carbon steel used, at the same time, low alloyed, in% by weight, 0.04% C, 0.21% Mn, 0.15 Si, 0.012 S, 0.015% P, 0.045% Al and 0.095% Zr, 0.09 Mo a 0.11% Ti, was prepared by hot rolling after preheating to 1280 ° C, at a rolling temperature of 870 ° C and at a coiling temperature of 620 ° C, and further by cold rolling on a 4 stool tandem for the final surface roughness. 1.0 microns and finally the strip was continuously hot dip galvanized in a zinc bath to form a coating of 120 gm. After winding, the coils were diffusion annealed in a flask furnace at a 3-hour ramp to 400 ° C and held at that temperature for 10 hours. Finally, the strip was easily rolled and removed by 1.0%. Achieved mechanical properties: yield strength (Rn) 240 MPa, strength limit (Rra) = 410 MPa and ductility (A 80) = 38%. Achieved values of corrosion resistance by testers according to the automotive industry standard / ONA no. 301011, respectively. Steinslag test / were on all samples in grade 1, which is 2 to 3 grade better. as in the case of comparable samples of stainless steel, annealed and uncoated, as well as low-carbon, hot-dip and electrolytically coated and subsequently unarmed. The visual test for the resistance to ^one mechaniokej the abrasion of the coatings of latex plating samples showed two -násobnú resistance. OBJECT OF THE INVENTION Welding method of metallized sheet metal strips for the automotive industry or for general purpose bent profiles of low carbon weldable steels with a basic composition in% by weight. based on carbon to 0.06%, sulfur from 0.002 to 0.030%, phosphorus from 0.005 to 0.035%, manganese from 0.1 to 3.0%, silicon from 0.05 to 0.20%, and aluminum from 0.03 up to 0,08% or low-alloyed molybdenum, titanium and zirconium in their total proportion up to 0,55%, or micro-alloyed with vanadium, nitrogen, titanium and zirconium in their total proportion up to 0,40%, hot rolled after heating to 1220 to 1280 ° C and at a rolling temperature of 820 to 880 ° C at a thickness of 1.8 to 4.0 mm, further cold rolled to a roughness of 0.4 to 1.0 micrometer and finally plated with zinc or zinc on both sides or with its alloys and / or a zinc-aluminum alloy with the addition of silicon and titanium or magnesium, with a thickness control of -2 -2 coatings in the range of 40 to 80 gm for one-sided or 80 to 160 gm for two-sided application, diffusely