DK151571B - PROCEDURE FOR THE MANUFACTURE OF ANCHOR STANDS OR ANCHORES AND THE USE OF THESE FOR EARTH AND CLIP ANCHORS. - Google Patents

Description

in 151571

The present invention relates to a method of producing anchor rods or ground wire for ground and / or mooring anchors, and to use rods made in this way as ground and / or mooring anchors.

Ground and mooring anchors usually comprise steel wire or steel rods which lie freely in a certain range of their length. These rods or wires are therefore highly exposed to corrosion and must therefore be protected against it. The ends of such ground and rock anchors are usually embedded in concrete over an anchorage stretch and exhibit between this anchorage and the ground surface an area of free clearance within which they lie freely and unprotected and are exposed to moisture from the ground. Therefore, in the area of this free range stretch, the 15 anchor rods or wires are highly subject to corrosion and, therefore, at known ground and rock anchors, the steel rods or wires are surrounded with a corrosion protection. Such corrosion protection is applied to the surface of the rods or wires, and when the surface 20 is damaged, there is a risk that the corrosion will start at the damaged places.

After incorporation, the corrosion protection is no longer controllable and there is therefore a risk that, if the corrosion protection in one place is defective, there will be a destruction in that location, so that such an earth and rock anchor can break over time. In addition, under the load of such an earth or rock anchor in the stretch of free range, there is an elastic extension which a coating such as corrosion protection cannot adequately follow. This creates the risk that fine cracks appear in the coating and that these cracks also cause destruction. This risk is especially present when such ground and rock anchors are to remain operational for long periods of time. Such ground anchors 35 must exhibit a high tensile strength.

The object of the invention is to provide a method for producing anchor rods or anchor wires of the kind mentioned above, which is characterized by a high corrosion resistance and strength properties corresponding to the purpose of use.

In order to achieve this object, the method according to the invention is essentially characterized in that 5 bars or wires of stainless austenitic or ferritic steel to obtain a tensile boundary ratio Rp0.2 / Rm of at least 0.7 cold deforming plastic, preferably by cold rinsing, cold rolling, cold embossing or cold stretching, whereby any heat treatment is avoided after the cold deformation.

Stainless steel austenitic or ferritic steel rods or wires have so far not been cold-deformed plastically in such a way that they have proved useful for ground anchors or rock anchors. This circumstance can primarily be attributed to the fact that a stressed steel is subject to increased wear by simultaneous chemical attack. Thus, it was assumed that cold deformed materials could be chemically attacked more easily. The invention, with the measure of compliance with a certain tensile boundary condition, demonstrates a way in which the necessary strength properties for the use of such anchor rods or anchor wires as earth or rock anchors can nevertheless be obtained without deterioration of the corrosion resistance. Preferably, the strength increase is carried out in the cold state until a tensile boundary ratio of at least 0.8 is obtained, preferably from 0.8 to 0.9.

The strength increase in the cold state can in principle be achieved by cold nipping, cold rolling, cold profiling, cold stretching, cold drawing, cold frying or the like. However, cold-drawing and cold-casting carry the risk of martensite formation, and martensite formation must be safely avoided by the cold deformation of the invention. Therefore, the former strength enhancement methods are preferred, with a deformation of a maximum of 20%, preferably about 20%, for cold stretching, cold rolling and cold stamping. 15%. Compliance with such deformation ensures that martensite is not formed and that the required tensile boundary ratio can be achieved. Degree of deformation here is understood to mean the longitudinal relationship between the end length and the output length, respectively the final cross-section and the exit cross-section of a test body. In a preferred manner, in order to obtain the required tensile boundary ratio, the cold winding is carried out to a thread height of 5 to 20 times, preferably 6 to 10 times the nominal diameter of the rod or wire. Also, with this measure, martensite formation is avoided with certainty, thereby achieving a significantly greater corrosion resistance. The formation of martensite would lead to a strong increase 10 of the tensile strength value. However, the tensile boundary ratio would at the same time decrease substantially and the required values could not be obtained.

Also, after the cold deformation of the invention, stainless steel does not need to be particularly protected against corrosion, and a surface treatment or coating is also essential. Because a stainless steel is insensitive to corrosion across its entire cross section, the strength of the soil or rock anchor is not sensitive to surface damage. Surprisingly, it has been found that the corrosion resistance of a cold deformed stainless austenitic or ferritic steel according to the invention satisfies all practical requirements. Despite the increased strength value, an increased corrosion attack could not be detected.

The invention further relates to the use of a cold, preferably cold-rolled, cold-stamped, cold-stretched or cold-rolled stainless austenitic or ferritic: steel having a tensile ratio of at least 0.7 to ground or rock anchors.

The invention will now be described in more detail from the following examples:

Steel bars of the varieties X 8 Cr 17 and X 5 CrNiMo 18 10 were analyzed, and the tensile limit, tensile strength and elongation were measured in twisted and uncut condition. At the rods 35, these were profiled rods with a nominal diameter those of 24 mm, which were provided with ribs, so that the degree of twisting could be clearly identified. The twisting of the 4 151571 rods occurred with a thread height detectable at the longitudinal ribs of 6 for steel bars X 8 Cr 17 and 10 for steel bars X 5 CrNiMo 18 10. The mechanical properties obtained for the said rods are listed in the following table 5 .

Chemical composition (% by weight).

Steel_C Si Mn Cr Ni Mo X 8 Cr 17 0.06 0.40 0.40 16.50 0.20 - 10 X 5 CrNiMo 18 10 0.03 0.65 1.60 17.0 11.0 2.15

Profile: Rod with longitudinal ribs, nominal diameter dg = 24 mm

Mechanical properties: 15 Steel black X 8 Cr 17

Tensile limit Tensile tensile elongation (%) R 0.2 boundary strength _ a 2 «ratio R A5 10 (N / mm) e 0.2 / 0“ 2.

µm (N / mm) 2q uncut 287_0.58_498_35.0_ twisted hiss; 555 ° '86 642 i4'58 6-de)

Steel type X 5 CrNiMo 18 10 25

Stretch-Stretch-Tensile-Break elongation (%) boundary boundary strength, «R 0.2 ratio R 5 10 2, R 0.2 / R 2> (N / mm) p 'm (N / mm) uncut 373_0.69_540 45.0_ 30 twisted 630 0.32 765 12.8 height = _

For steel X 8 Cr 17, this is a ferritic 35 steel whose tensile boundary and tensile strength were increased in such a way by the twist that the tensile boundary ratio also assumed a significantly greater value. Despite the increase in the value of tensile limit and tensile strength, a substantially unchanged corrosion resistance was found. Analocrt age for steel 5 151571

An additional steel of the type TOR 650/750, designated 18 10 2, which is also a stainless austenitic steel, found an analysis on C Si Mn Cr Ni Mo (%) 5 0.038 0.16 1.80 17.90 12, 72 2.15 and the mechanical properties after cold deformation were

Stretch boundary Stretch boundary- Tensile strength Break elongation

RO .; 2 ratios R A

P o m o A5 (N / mm) (N / mrn) 10 655 0.87 755 26.3

A further stainless steel of the type 16 6 1 (TOR 750/900) showed an analysis on C Si Mn Cr Ni Mo N (%) 0.10 0.64 5.60 16.88 6.30 1.11 0.23 15 and the mechanical properties after cold deformation were

Tensile limit Tensile limit- Tensile strength Break elongation R 0.2 ratio R

(N / mm2) V · 2 / ** (N / mm2) 5 20 815 0.83 985 28.3

The stainless austenitic chromium nickel steel, with the standard designation 16 6 1, exhibited a tensile limit of 210 N / mm, a tensile strength of 480 N / mm and an elongation A. of 45%, prior to cold deformation 2. With twisting 25, the tensile strength was increased to 985 N / mm and the tensile limit 2 to 815 N / mm at an extension of 28.3, maintaining the corrosion resistance.

For ferritic corrosion resistant steel profiles with the standard designation X 8 Cr 17, the following 30 analysis values generally apply: C Si Μη P S Cr max. max. max. max. max. 15.5 0.10 1.00 1.00 0.045 0.030 17.5

The mechanical properties of such steel profiles can be readily adjusted by cold coining to: 2

Tensile limit (R 0.2): at least 500 N / mm P 2 tensile strength (Rm): at least 600 N / mm and fracture elongation (A ^): at least 12%, giving a minimum tensile ratio of 0 on the basis of the tensile and tensile values. , 83rd

Claims (10)

151571 Patent Claims. Method for producing anchor rods or ground and / or mooring anchor rods, characterized in that rods or strands of stainless steel 5 austenitic or ferritic steel to achieve a tensile strength ratio R.0.2 / R of at least 0.7 cold deform P m plastic , preferably by cold rubbing, cold rolling, cold stamping or cold stretching, whereby any heat treatment is avoided after the cold deformation. The method according to claim 1, characterized in that the strength increase in the cold state is carried out to obtain a tensile boundary ratio of at least 0.8, preferably from 0.8 to 0.9. A method according to claim 1 or 2, characterized in that in the case of cold stretching, cold rolling and cold stamping, there is a deformation degree of maximum 20%, preferably approx. 15%. Method according to claim 1 or 2, characterized in that the cold coiling is carried out to a thread height of 5 to 20 times, preferably from 6 to 10 times the nominal diameter of the rod or wire. 5. The use of a cold-deformed, preferably cold-rolled, cold-stamped, cold-stretched or cold-twisted stainless, austenitic or ferritic steel with a yield strength ratio of at least 0.7 to ground and rock anchors. Use of a thread height of 5 to 20 times, preferably 6 to 10 times, its nominal diameter twisted round steel according to claim 5 for the purpose of claim 5. Use of a deformation degree of maximum 20%, preferably approx. 15%, by cold stretching, cold rolling or cold stamping deformed steel according to claim 5 for the purpose of claim 5. Use of a steel of the X 8 Cr 17 35 steel according to claim 5, 6 or 7 for the purpose of claim 5. Use of a steel of the X 5 CrNiMo 18 10 steel according to claim 5, 6 or 7 for the purpose of claim 5. 151571 Use of an austenitic chromium nickel steel of the composition C Si Mn Cr Ni Mo N (%) 0.10 0.64 5.60 16.88 6.30 1.11 0.23 Residual Iron and Steel Accompaniment, according to claim 5, 6 or 7 for the purpose of claim 5.