FI74737B - FOERFARANDE FOER TILLVERKNING AV VALSTRAOD MED GODA KALLBEARBETNINGSEGENSKAPER. - Google Patents

Description

1 74737

Method for the preparation of wire rod with good formability

The invention relates to a method for producing a wire rod having good ductility. DE 27 27 780 already discloses a method for producing wire rod, in which the wire leaves the last pulp chair with an average final rolling temperature of 870 to 970 ° C, after which the wire is finally rapidly cooled to 700 to 850 ° C with water and then the wire is further cooled in the applied state o at an average cooling rate of less than 8 C / s, in particular o to a temperature of 300 to 600 C. This known method is used for several steels with a Si content of 0.5-1.5%, whereby the cross-section of the wire rod is provide a homogeneous structure with the desired mechanical properties. In particular, the known method must avoid the formation of bainite or martensite on the surface of the wire, in which case Due to the rapid cooling to a relatively low application temperature, the known method still provides a thin, firmly adhering carbon layer and a smooth fruit surface.

The object of the invention is to further improve the ability of certain steel grades to form, and in particular to form, to reduce hardening, to facilitate mechanical abrasion and to improve the adhesion of lubricants to the surface. In order to solve this problem, the invention is essentially characterized in that for soft tensile grades, a wire made of steel having the following composition: 2 74737

0.003 to 0.20 weight-ϊ C

0.001 - 0.40 "Si 0.15 - 0.65" Μη

0.001 - 0.1 11 AI

0.0001 - 0.035 "P

0.0001 - 0.035 "S

and optionally 0.001-1.5 "Cr 0.001-2.0" Ni 0.001-2.5 "Mo

0.001 - 0.5 "V

0.001 - 0.5 "Ti

0.0001 - 0.03 "B

0.001 - 0.5 "Zr and the rest of the steel and conventional impurities, starting at o 950 - 1100 C The final heating temperature is first subjected to o water and air cooling to a temperature of 900 - 1050 C and then applied and slowly cooled below oo At a speed of 4 C / s for temperatures between 200 and 350 C.

Alternatively, in order to produce a wire with good cooling properties, it is possible to process a wire made of steel having the following composition:

0.04 to 0.5% by weight C

0.01 - 0.4 "Si 0.15 - 1.5 M Mn 0.001 - 1.0" Cr 0.001 - 1.5 "Ni 0.001 - 0.5 M Mo

0.001-0.5 "V

0.001 - 0.1 'AI

0.001 - 0.03 ”B

0.0001 - 0.045 "P

0.0001 - 0.045 "S

3 74737 and the remainder of the iron and conventional impurities, leaving o 950 to 1100 C 1, the final discharge temperature is first subjected to o water and i1 cooling to a set temperature of 850 to 950 C and then slowly applied and cooled oo about 4 C / s: n at a rate of <300 C to heat the room.

Higher outlet temperatures for both the final rolling temperature and the application temperature provide a relatively rougher quality of structure with a larger secondary grain size compared to the prior art.

The structure is kept close to the equilibrium state in the stationary air by means of the slow cooling of the applied spool winding and thus lower yarn strengths are obtained.

However, this also results in lower curing in the thermoforming of this wire rod, as a result of which higher degrees of thermoforming can be achieved. The method according to the invention provides a relatively coarse scale formation with a correspondingly thicker layer of scale, which leads to a substantial improvement in mechanical scale removal. Finally, a wire rod with a higher surface roughness is obtained, which provides better adhesion of the lubricants for cold forming, so that in turn promotes the cold forming process.

In this way, grain sizes between ASTM values 5 to 7 can be obtained, in contrast to which, according to the prior art, substantially finer grain sizes between ASTM values 7 to 8 are obtained. Such a roll wire can be subjected to very high gy 1 molding without intermediate annealing.

In the method of manufacturing a wire having good abrasion properties, it has been shown that, for example, a wire rod with a diameter of 3 mm can be formed into screw frames without additional heat treatment. It was even found that without heat treatment, it is possible to manufacture inibus screws with vending machines.

The method according to the invention is particularly suitable for use on wire rod with a diameter of 5.5 to 14 mm.

Preferably, the final rolling temperature is 970 to 1100 ° C, with a second cooling to 250 to 300 ° C.

Especially in soft traction grades, it is done so that the cooling rate after application o is 1.0 - 3.5 C / s.

The invention is explained in more detail below by means of exemplary embodiments and figures of the drawing. In the drawing, Fig. 1 shows a roughness profile using a method according to the prior art, and Fig. 2 shows a roughness profile using a method according to the invention for soft tensile qualities according to Embodiment 1.

Example 1

To obtain a soft tensile quality, a steel having the following composition is used: 0.02 wt% C, 0.003 wt% SI, 0.25 wt% Mn, 0.022 wt% P, 0.018 wt% S; 0.004 wt% Al. Starting from a final rolling temperature of 1030 ° C, it was first cooled to an annealing temperature of 950 ° C and then further cooled in an air-applied state at a rate of about 2.5 ° C / s. The tensile strength R obtained in this way was 330 N / mm and the yield strength R 220 n / mm.

m eh In this way, the wire rod illuminated in this way could be drawn from a diameter of 5.5 mm or less without intermittent annealing to a diameter of 0.5 mm, so that the rest of 1200 N / mm was not exceeded.

For comparison, a steel substantially corresponding to the steel of claim 1, having a Μη content of 0.35% by weight, was subjected to the same wire diameter of 5.5 mm and a winding distance of the conveyor belt of af * 10 mm to various prior art treatments according to the data of Example 1 and Example 1. . The grain sizes according to the ASTM standard obtained in this case are compared with each other in the following table, in which only experiment 3 was carried out in accordance with the method according to the invention according to Example 1 and experiments 1 and 2 were carried out according to the prior art.

table 1

Experiment Application 1temperature- Grain size (according to ASTM standard) mode (C) Edge Core 1,800 9 - 10 10 2 850 7-8-9 8-9 3 950 6-7 7

It can be seen from the above table that according to the invention at a higher application temperature of 950 ° C, observing an average cooling rate of 2.5 ° C / s gives a substantially higher grain both at the edge and in the core than according to the prior art. This larger grain size results in a smaller increase in strength in ky 1 molding and thus a considerably higher achievable degree of cold molding.

The roughness achievable according to the prior art and the method of Example 1 is compared in Figures 1 6 74737 and 2. While the roughness profile shown in Figure 1 produces a maximum profile R of 4.01 μm according to the prior art, as can be seen in Figure 2, according to the method described in Example 1, a maximum profile depth R of 8.77 μm is reached. From this depth / depth of the profile of the rolled wire produced according to the invention, a better adhesion of the lubricants to the surface is obtained and thus the cold forming process is modified. The symbol R in Figures 1 and 2 denotes the average profile depth according to DIN 4768 as μm.

The symbol R denotes the leveling depth in μm and P / denotes R the mean roughness value in μm. The schematic diagram of the surface a / clearly forms a different roughness profile when comparing the prior art method with the method of Example 1.

Example 2

To produce a wire with good cooling properties, the starting material was made of steel having the following composition: 0.35 wt-¾ C, 0.25 wt% Si, 0.70 wt% Mn, 0.024 wt% P, 0.022 wt% S , 0.032% by weight of Al, 0.002% by weight of B. The final evacuation temperature was chosen to be 1050 C and the evacuation temperature of 1 ac to 870 C. .

This treatment gave a tensile strength of R 570 2 2 m N / mm and a yield strength of R 300 N / mm. This wire rod eh could be processed starting from a diameter of 8 mm without additional heat treatment to properly screw frames. Due to the low strengths of the wire, very low tool consumption was also obtained.

Claims (4)

A process for the manufacture of roll wire having good machining properties, characterized in that the wood for soft wire products is manufactured from a steel having the following composition: 0.003 - 0.20% by weight C 0.001 - 0.40 "SI 0.15 - 0 , 65 "Mn 0.001 - 0.1" Al 0.0001 - 0.035 "P 0.0001 - 0.035" S and possibly 0.001 - 1.5 "Cr 0.001 - 2.0" Ni 0.001 - 2.5 "Mo 0.001 - 0.5 "V 0.001 - 0.5" Ti 0.0001 - 0.03 "B 0.001 - 0.5" Zr and the rest iron and conventional impurities, starting from 950 - 1100 C final rolling temperature, first being exposed to water - and air cooling to the temperature of 900-1050 ° C, after which it is spread out and cooled slowly to a temperature of 200-350 C at a rate less than 4 ° C / s. 2. A method for producing rolls with good working properties, characterized in that the trees, for producing a tree with good cutting properties, are made of a steel having the following composition;