DE1921168B1 - Process for the production of welded wire mesh - Google Patents

Description

The invention relates to a method for producing Welded wire mesh, also called welded wire mesh, made of bulk steel, e.g. B. Thomasstahl, with a maximum carbon content of 0.18% and a nitrogen content of 0.004 to 0.008 0 / ,, in which the bulk steel on a wire or fine iron mill to Bar steel is rolled and the bar steel is cooled and cold-formed into welded wire mesh is welded and tempered at 100 to 300 "C.

The bulk steel from which welded welded wire mesh is made, above all it must be weldable accordingly. That means that the mass steel one May have a carbon content of 0.18% or less. The yield point must be greater be than 50 kp / mm2.

The desired values of the yield strength are at the low carbon content of mass-produced steel, for which expensive alloy additives are not possible Cold forming achieved. In addition, the bulk steel must have an elongation (L = 10xd) of have over 801o. In practice, this elongation value is usually negligible be crossed, be exceeded, be passed. The steel bars must finally pass a standardized rebending test and mostly a profiling to improve the adhesion in the concrete on its surface have e.g. B. be provided with rolled-on ribs. The usual procedure for The production of welded wire mesh from bulk steel is therefore marked as follows: The starting point is generally a bulk steel, e.g. B. Thomasstahl, which has a carbon content of 0.15% and a manganese content of 0.5 to 1.00 /, and is often cheaper the production is shed with half peace of mind. A typical composition of a Bulk steel used for the production of welded wire mesh is z. B. the following: 0.12 ovo C, 0.05 0 /, Si, 0.8 ovo Mn, 0.035 0 /, S, 0.040 O / o P, 0.008 0 /, N, remainder Iron and usual impurities, with stronger cold forming also: 0.10 ovo C, 0.05 O / o Si, 0.5 ovo Mn, 0.035 0 / o S, 0.040 0 /, P, about 0.004 to 0.008 0 / o N, remainder Iron and common impurities.

This bulk steel is made on a wire or fine iron mill Bar steel is rolled, the bar steel is cooled and sent to the manufacturer of the welded wire mesh delivered. There the bar steel is descaled and to achieve the desired Value of the yield point cold deformed, namely with a deformation of about 40 01o drawn. Insofar as profiling is required, this will then be provided in the cold state applied. The profiled bar steel is then on the required Cut to lengths and welded to a reinforcement mesh. Finally the welded wire mesh left open on one occasion.

A method for producing welded wire mesh is also known (Swiss patent 408 082), in which the made of soft, unalloyed steel rolled steel bars quenched in a cooling liquid immediately after rolling is to increase the strength properties of the steel bars significantly. Preferably the steel bars are heated to temperatures of 50 to immediately after rolling 100 "C quenched. The quenched steel bars must then be cold-worked be e.g. B. be directed or profiled.

In another known method of manufacturing welded wire mesh (USA.-Patent 3,307,637) is based on a fine-grain steel, the has a carbon content of 0.15 to 0.40%. In this procedure, again the steel rolled into bar steel as well as the bar steel from a temperature between 800 and 900 "C quenched to about 500" C.

Finally, there is a method of making welded wire mesh known (German patent specification 968 319), in which the steel is rolled into bar steel and the steel bars are quenched immediately after rolling and then cold is deformed in order to improve its strength properties, in particular its flexibility, to improve.

The known processes for the production of welded wire mesh go made of relatively cheap steel, so-called bulk steel, but are nevertheless, because of the necessary cold working and the application of the profiling in cold condition, expensive. In the latter case it is disadvantageous because of the necessary tread depths, considerable tool wear is also noticeable. A Another major disadvantage of the known method for producing welded wire mesh can be seen in that the achievement of the required values of the yield point through the relatively strong cold working poor toughness properties of the bar steel results, which is expressed in the low elongation of only 80 / o. On the part of Consumers and the licensing authorities there is indeed a desire for a steel bar which, ceteris paribus, has higher elongation values, but one has to deal with it found that higher values of the elongation with the usual technical means are not can be reached.

The invention is therefore based on the object of specifying which way welded wire mesh is made from bulk steel with increased values of elongation can be.

The inventive method for the production of welded wire mesh Made of bulk steel with a maximum carbon content of 0.18% and a nitrogen content from 0.004 to 0.008 0 / o, in which the bulk steel on a wire or fine iron mill is rolled into bar steel and the bar steel is cooled, cold-formed, into welded wire mesh is welded and tempered at 100 to 3000 C, is characterized by that the steel bars rolled in a known manner at 1100 ° C, from the rolling heat Quenched in water to 800 to 1000 ° C, to 150 to 550 ° C in a fluidized bed cooled and then by bending or twisting with an edge deformation is deformed by 100 / o. Fluidized bed refers to a fluidized bed from through a gas stream, e.g. B. air flow, fluidized, fine-grained heat carriers. Preferably If profiling of the steel bars is required, the profiling is used rolled onto the steel bars on the wire or fine iron mill. To the bending deformation to carry out, the steel bars are guided over a roller; about the torsional deformation perform, the steel bar is twisted in a known manner. Generally will the bending or twisting deformation is followed by straightening.

The invention avoids the disadvantages of the known methods for Manufacture of welded wire mesh and, above all, makes it possible with much less Expenditure to produce welded wire mesh. Surprisingly is at Applying the method according to the invention readily yields a yield strength of over 50kp / mm2 and an elongation of over 10%, preferably even over 130 / o, is achieved.

The advantages achieved by the invention are summarized therein to see that the cold working takes place as edge deformation so that the core of the steel bars remains relatively soft, so the toughness properties are significantly improved will. According to the invention, it was recognized that the required strength properties can be achieved with relatively little effort if after quenching in Because of this type of water the further cooling takes place in a fluidized bed Cooling even when the bar steel is already on the wire or fine iron mill has been provided with a profiling, this profiling a uniform Cooling down not prevented.

In the following the invention is explained in more detail using an exemplary embodiment explained.

A bulk steel with 0.15 0 / o C, 0.05 0 / o Si, 1.0 Ole Mn, 0.040 0 / o P, 0.0250 /, S and 0.015% N were rolled into bar steel with a diameter of 8 mm and provided with a rib profile during rolling.

After rolling, the steel bar was raised from 1050 to 900 ° C with water and then cooled to 450 ° C. in a fluidized bed. The mean cooling rate was 200 C / sec. The following values resulted: tensile strength (kp / mm2) = = 56 Yield strength (kp / mm2) = = 37 Elongation at break (at L = 10xd in Ob) .. = 25 Then the steel bar was wrapped around a roll of 80 mm diameter with a wrap angle bent from 1800. After this cold deformation (edge deformation 100 / c), the result was following values: tensile strength (kp / mm2) ...... = 63 yield point (kp / mm2) ...... = 53 Elongation at break (at L = 10xd in Ob) .. = 13 After bending, the bar steel straightened in a stirrup leveler. As expected, the judging resulted in a Reduction in strength properties. The following values were obtained: tensile strength (kp / mm2) ...... = 62 yield point (kp / mm2) ....... = 47 elongation at break (at L = 10xd in Ob) .. 18 A reinforcement mesh was welded from the straightened steel bars, which Was tempered for 5 minutes at 220 ° C (residence time in the tempering furnace 30 minutes). To after tempering, the following values were measured on the welded wire mesh: tensile strength (kp / mm2) ....... = 67 yield point (kp / mm2) ....... = 60 elongation at break (at L = 10xd in Ob) .. = 15 The steel bars showed excellent properties for a welded wire mesh. The elongation corresponds exactly to a Hooke's straight line up to the yield point, after that there is the beginning of flow and a strong stretching to the point of tearing.

It is surprising that the welded wire mesh explained in the exemplary embodiment with a yield strength of 60 kp / mm2, which is significantly above the norm, with 150 / o the value required in Germany for the elongation of at least 80 / o to almost 100% and the welding of the steel bars to the welded wire mesh the strength properties not affected.

Claims (4)

Patent claims: 1. Process for the production of welded wire mesh from bulk steel with a carbon content of 0.18% and a nitrogen content of 0.004 to 0.008 ° / o in which the bulk steel is rolled into bar steel on a wire or fine iron mill is cooled as well as the steel bars, cold formed, welded to welded wire mesh and is tempered at 100 to 300 ° C, characterized in that the steel bar rolled in a manner known per se at 1100.degree. C., from the rolling heat in water to 800 Quenched to 10000 C, cooled to 150 to 5500 C in a fluidized bed and then by bending or twisting with an edge deformation of 10% is deformed. 2. The method according to claim 1, characterized in that on the Wire or fine iron mill on the steel bars a profile is rolled. 3. The method according to claim 1 or 2, characterized in that the cold-formed bar steel is straightened. 4. Application of the method according to any one of claims 1 to 3 a bulk steel with 0.15% carbon, 0.05 silicon, 1.0% 0 / <> manganese, 0.040 0 / o phosphorus, 0.0250 /, sulfur and 0.015 0 / <> nitrogen.