EP0198024A1 - Procede de fabrication d'un acier pour precontrainte. - Google Patents

Procede de fabrication d'un acier pour precontrainte.

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Publication number
EP0198024A1
EP0198024A1 EP85905199A EP85905199A EP0198024A1 EP 0198024 A1 EP0198024 A1 EP 0198024A1 EP 85905199 A EP85905199 A EP 85905199A EP 85905199 A EP85905199 A EP 85905199A EP 0198024 A1 EP0198024 A1 EP 0198024A1
Authority
EP
European Patent Office
Prior art keywords
hardening
grain
mass
strength
steel
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP85905199A
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German (de)
English (en)
Other versions
EP0198024B1 (fr
Inventor
Max Willy Tischhauser
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Individual
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Individual
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Publication date
Priority claimed from CH5210/84A external-priority patent/CH667104A5/de
Priority claimed from DE19853535886 external-priority patent/DE3535886A1/de
Application filed by Individual filed Critical Individual
Priority to AT85905199T priority Critical patent/ATE51897T1/de
Publication of EP0198024A1 publication Critical patent/EP0198024A1/fr
Application granted granted Critical
Publication of EP0198024B1 publication Critical patent/EP0198024B1/fr
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment
    • C21D8/06—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires
    • C21D8/08—Modifying the physical properties of ferrous metals or ferrous alloys by deformation combined with, or followed by, heat treatment during manufacturing of rods or wires for concrete reinforcement

Definitions

  • the invention relates to a method for producing high-strength, weldable, corrosion-resistant and brittle fracture-proof prestressing steels.
  • prestressing steels are generally produced from unalloyed, high-carbon, high-grade structural steels, specifically
  • these known prestressing steels have deficiencies regarding the mechanical properties of the susceptibility to corrosion and, in particular, the insensitivity to brittle fracture, in spite of hardly any significantly changed concepts with regard to their chemical composition, structure and manufacturing conditions.
  • a fact that has so far been overlooked in the assessment of prestressing steels is that the susceptibility of prestressing steels to brittle fracture can begin considerably above 0 ° C and increases rapidly at lower temperatures. The safety against brittle fracture is expressed with the so-called transition temperature for possible brittle fracture.
  • Conventional prestressing steels usually have a Tu of significantly above + 20 ° C !.
  • Corrosion occurs in prestressing steel in a variety of forms, whether as trough, hole, gap, intercrystalline and transcrystalline corrosion. Particular attention should be paid to stress corrosion cracking.
  • the corrosion-inhibiting properties of copper are known, however
  • Copper as an alloying element has so far not been used in prestressing steels.
  • thermomechanical treatment which takes place after solidification from the melt and reheating from a second heat, wherein
  • The- temperature limit uss due to the copper present in the steel, since effective solidifying deposition of copper can only be achieved by accelerated cooling from approx. -850 ° C to around 650/550 ° C without rolling. that at a temperature below 850 ° C there is no longer any precipitation of copper during rolling.
  • thermomechanical treatment produces wire rod grades for the production of cold-drawn wire, three-wire strands, seven-wire strands and tension rods, which correspond in their properties to the Euro standard 138, but the additional usage properties (more corrosion-resistant , resistant to brittle fracture and weldable). Costly cold forming (stretching) and subsequent tempering are omitted for tensioning rods, which already means a considerable advantage of the invention.
  • a third stage of the treatment can also be provided, in which rolling is again carried out in a controlled manner from about 650/550 ° C. with one or a few passes, that is to say with a high degree of deformation at high speed.
  • a dwell time and a delayed cooling, for example in still air, are considered below.
  • an increased precipitation hardening process results in an increase in strength of over (ind.) 40% compared to conventional prestressing steels.
  • the accompanying diagram serves to illustrate this process sequence.
  • the steel can additionally be strain hardened, provided that higher strength classes are aimed for or are necessary.
  • thermomechanical treatment the mechanisms of increasing strength due to the chemical composition and the targeted metering of the microalloying elements work together additively.
  • These mechanisms are in particular fine grain hardening, mixed crystal hardening and very particularly precipitation hardening, in which the alloying element copper is particularly effective.
  • the dosage of the alloy elements is designed so that not only the strength is increased considerably, but also the toughness is increased at the same time, in particular through the fine grain hardening.
  • the targeted dosing of the alloying elements also ensures that the highest degree of solidification takes place via precipitation hardening. Elimination in ferrite is the most effective for increasing strength.
  • Precipitation hardening in particular due to the accelerated cooling and a low final rolling temperature with a high degree of deformation and a high rate of deformation followed by a delay after the final deformation and delayed. Cooling achieves the highest effect of the increase in strength, this phase of thermomechanical treatment is also of the greatest importance, because through this phase the targeted dosing of the alloying elements also achieves the highest safety against brittle fracture, in particular through the interaction of the elements Manganese and molybdenum.
  • Precondition for an effective increase in strength in the sense of the invention is furthermore the fine-grain hardening, a fine-grain depletion being required for its optimal realization, which simultaneously increases the toughness.
  • the grain size to be achieved according to ASTM 112 should be at least 9, but if possible at least 12, to which an increased manganese content of 1.45% on average contributes.
  • an austenite grain that is as fine as possible should already be aimed for, since this also determines the size of the ferrite grain.
  • the microalloying elements provided in the directional analysis in particular aluminum, nitrogen, niobium and vanadium, are incorporated into the austenite structure to inhibit grain growth and to form strength-increasing obstacles to dislocations due to fine precipitations.
  • a particle size of 100 to 200 X is most effective for this, the
  • the fine grain melting should include the following stages according to the invention:
  • a steel aftertreatment in particular an inert gas purging, a vacuum treatment, a deoxidizing, full sedation, and, if possible and relevant, an inclusion modification and / or a pan treatment with metallic calcium or calcium halide slags.
  • Continuous casting is a good choice for casting. Continuous casting is the most economical and at the same time the best quality way of casting and solidifying the molten steel into the primary material used for the manufacture of prestressing steel: billets. To ensure a high level of quality required for prestressing steels, special measures must be taken to prevent such defects, such as, to avoid core defects such as mitigating and solidification bridges and surface defects. B. Reoxidation protection, concealed casting, electromagnetic stirring.
  • the low carbon content of 0.1% provided in the directional analysis largely prevents the occurrence of the abovementioned defects and at the same time favors the economy of continuous casting for the production of prestressing steel grades, since the costly measures are more extensive than for conventional ones , high-carbon prestressing steel grades are required, while at the same time ensuring a high degree of purity, homogeneity and quality.
  • the mixed crystal hardening acts through the type of chemical composition, the influence of the foreign atoms in substitution mixed crystals and the interstitially dissolved foreign atoms being of particular importance.
  • the influence of the different alloy elements can be explained by the distortion that these elements cause in the lattice. The greater the distortion, the higher the increase in strength.
  • fine grain hardening has to be given the most consideration because the hardening mechanism resulting from it is characterized not only by an increase in strength but also in a simultaneous increase in toughness. Furthermore, the 'two-dimensional obstacles are just for migratory Versetzun ⁇ gen so strong obstacles that they can not be overcome über ⁇ of these. The dislocation has then become impossible and numerous dislocations form a build-up at the grain boundary, which results in a significant stress concentration and therefore an influence on strength. However, the average grain size influences the lower yield strength.
  • thermomechanical treatment is intended to subsume a number of specially controlled shaping processes in which the influencing factors
  • thermomechanical treatment in the context of the invention is carried out by a very specific sequence of controlled rolling of the microalloyed and fine-grained steel specifically developed for this purpose, in particular setting a low final rolling temperature, rapid cooling before the last rolling pass and a high degree of final deformation, so that the Recrystallization leads to the finest possible austenite grain before the ferrite-pearlite transformation.
  • the rolling process additionally causes hardening of mixed crystals as well as fine grains and particles by the precipitation of carbides, nitrides or carbonitrides.
  • the temperature control is alloying and by rolling so ge controls that Diev - ⁇ A- conversion shortly before and / or after the lowest possible final rolling temperature, which comes to lie shortly before A 3, takes place. In any case, the formation of martensite should be excluded.
  • the carbonitrides can precipitate in austenite, during the ⁇ * - ⁇ transformation or in ferrite. Elimination in the ferrite is most effective for increasing the strength.
  • the kinetics, the extent and the temperature of the precipitations depend not only on the thermodynamic conditions, but also on the diffusibility of the alloy atoms, the degree of hypothermia and the germ conditions of the precipitates.
  • thermomechanically acted, cold-stretched tension rods or wire rod for the production of cold-drawn tension wires and Lit ⁇ zen from it.
  • the final rolling temperature and the degree of deformation, in particular in the last pass, are decisive for the mechanical properties that can be achieved.
  • the pearlite content decreases, which means that low-carbon, micro-alloyed structure structures in the controlled final rolled state have only a low, often no pearlite content in the structure.
  • the mechanical properties are thereby additionally favorably influenced.
  • thermomechanical treatment The last stage of the process following the thermomechanical treatment is work hardening, which in particular consists of stretching or drawing.
  • This subsequent cold working which is used to manufacture all prestressing steels and for which the steels of the new design are particularly well suited, once again results in a considerable increase in strength compared to today's prestressing steel grades by means of the degree of deformation to be used.
  • Niobium has the most effective influence of possible microalloying elements the fine grain hardening and hardening by the thermomechanical treatment, ie the increase in strength, is followed by vanadium. The same applies to the improvement of the transition temperature.
  • niobium alloy results in a much larger proportion of fine-grain hardening than hardening and therefore not only a higher yield strength than with a titanium or vanadium alloy, but above all, as already mentioned, a very favorable low transition ⁇ temperature.
  • the high ratio of fine grain hardening to hardening through the addition of niobium is therefore a major reason why niobium must be used here, since niobium also causes the greatest reduction in the transition temperature.
  • Manganese and nickel as well as silicon with contents below about 0.5% also shift the transition temperature to lower temperatures.
  • grain refinement In addition to solidification, grain refinement also leads to a significant improvement in toughness, which is manifested in a sharp reduction in the transition temperature. In addition, the desired influence is reinforced by a decreasing pearlite content. Low-pearlite steels are therefore generally particularly insensitive to brittle fracture in the case of fine ferrite grains.
  • the sulfur content plays the decisive role in the anisotropy of toughness, the most important factor influencing the cold formability.
  • a desired lower sulfur content ie a reduced number of sulfide inclusions, considerably improves the toughness with regard to constriction of the fracture, a property which is particularly important for prestressing steels.
  • the reduction in the sulfide length is particularly effective for a more favorable constriction of the fracture.
  • the mechanical properties that can be achieved with calcium treatment have a significantly reduced spatial anisotropy of the toughness properties.
  • the constriction of the fracture which is so important for ensuring the quality values for prestressing steels, is improved considerably by the calcium treatment and with a decreasing sulfur content.
  • Desulphurization should be carried out to below 0.020 mass% if possible.
  • molybdenum-niobium-alloyed structural structures result in the best properties.
  • An additional improvement in the properties is achieved by the combination of niobium-vanadium-molybdenum-copper with simultaneous thermomechanical treatment according to the invention, the best results being achieved by using a low final rolling temperature and the highest possible degree of final deformation.
  • the speed of rolling and cooling and the cooling in bed are also effective for the production of prestressing steels. Both strength and toughness improvements are found down to 750 ° C.
  • the effective The mechanisms which are responsible for the increase in strength are increased considerably by alloying with molybdenum and by regulating the rolling speed with the purpose of reducing the f - ⁇ - conversion as far as possible in the range between 650 and 550 ° C, just 'a region in which the strength-enhancing mechanisms, in particular by precipitation hardening are most effective.
  • the most effective means of achieving optimal mechanical properties is, however, the production of extensive fine grain.
  • the refinement of the grain size causes an increase in the yield strength with a simultaneous improvement in the transition temperature.
  • the aim is to achieve the finest possible austenite grain, since this also determines the size of the ferrite grain.
  • a general empirical value is that a reduction in the size of the austenite grain has a factor of around 0.3 on the reduction in the size of the ferrite grain.
  • the essential process in the growth of the austenite grain is not the dissolution of the precipitates, but their aggregation into large and thus effective particles.
  • One measure for controlling the austenite grain size is the incorporation of fine precipitates in the austenite structure, which inhibits grain growth.
  • aluminum which produces this effect via aluminum nitride
  • it is primarily the microalloying elements niobium, vanadium and titanium in particle sizes from 100 to 200 ⁇ which are comparable in their carbides, nitrides or carbonitrides Come into effect. Show the most favorable conditions for preventing the sharp increase in grain growth when reheating in the pusher furnace for rolling higher aluminum contents (up to 0.050%) and nitrogen contents (up to 0.020%). With increasing niobium content, the start of the sudden grain growth is also shifted to higher temperatures.
  • austenite grain can also be refined by means of higher degrees of deformation. The grain refinement effect is most pronounced at low final deformation temperatures.
  • the lower transformation temperature causes a higher nucleation frequency and a lower mobility of the grain boundaries, which results in a reduction in the ferrite grain size .
  • the delay in austenite recrystallization can also be controlled by controlling the cooling rate Alloying of small amounts of molybdenum to the microalloyed, low-pearlite structure is favored, whereby the i-pC conversion is shifted to lower temperatures. This possibility is used in the thermomechanical treatment, whereby an even more fine-grained structure is achieved with an additional improvement in the transition temperature.
  • incoherent niobium vanadium and titanium carbonitrides have different effects on the ferrite grain size in their effective particle size and quantity.
  • vanadium In the thermomechanically treated state, vanadium only causes a weak grain refinement.
  • the basic composition plays a role in that higher carbon and nitrogen contents result in a finer secondary structure via a stronger or faster excretion before or during the> ⁇ * - o conversion.
  • the optimal Grain refinement due to niobium contents between 0.04 and 0.10% is uniformly effective, but those of titanium and vanadium are also increasingly effective with increasing contents.
  • the carbon and nitrogen content of the steel influences the ferrite grain size considerably less in steels with niobium than in those with vanadium. With decreasing carbon contents, the influence of the nucleation by excreted particles on the grain size decreases in favor of a very pronounced and, in the present case, desirable inhibition of recrystallization by dissolved niobium. Low-pearlite steels therefore have smaller ferrite grain sizes in the thermomechanically treated state than steels with a higher carbon content.
  • Dissolved vanadium, niobium or titanium cause a further fine grain effect by delaying the austenite conversion desired here. Rising manganese contents also lower the transition temperature, ensure optimum particle separation and thus the optimal effect of particle hardening.
  • the setting of the lowest possible final rolling temperature accommodates and at the same time enables the optimal separation, for example of copper, interacting to achieve a maximum possible increase in strength.
  • Extensive microstructure refinement occurs as a result of increased germ density and growth hindrance of the newly formed ferrite grains.
  • the hardening maxima occur in the temperature range between 550 and 650 ° C. This can be explained by the effect of the chemically non-detectable coherent precipitates (clusters) of niobium, carbon and nitrogen atoms (including titanium), which precede the incoherent precipitate.
  • the drop in the yield point is of importance. This drop is caused by increasing temperatures or exceeding the holding time and is due to the reduction of the coherent stresses when the coherent particles change into incoherent and the subsequent waxing of the particle diameter and quantity.
  • the starting material (crude steel) for carrying out the method according to the invention is to use a steel which has the following alloying elements in its directional analysis:
  • the carbon content causes a substantial solidification and plays an important role in this context.
  • the carbon content via the pearlite component exerts the most significant negative influence on the brittle fracture safety (transition temperature) also given in this development, as well as on the weldability, and this with increasing pearlite content, this is To limit the carbon content to proportions which both permit an increase in strength and an improvement in the corrosion resistance, but also enable the safety against brittle fracture to be improved down to around -40 ° C. and also make it weldable.
  • the desired fine grain formation to be aimed at it should also be taken into account that the carbon content has a considerable influence on this.
  • Manganese has a particularly fine grain refinement and at the same time through solidification of solid solution and increased hardening, so that the manganese content should preferably be placed at the upper limit, because the increase in strength due to manganese depends very much on the pearlite content and, due to a suitably low pearlite content, also a favorable transition Temperature and thus also guaranteed brittle fracture safety.
  • Increasing manganese levels provide a significant contribution to the delay of the 'desired austenite transformation here and thus cause an optimum fine grain formation. With the simultaneous presence of niobium and vanadium as microalloying elements, the increasing solidifying proportion of manganese becomes effective in the case of low-pearlite structures with increasing manganese content.
  • the latter for manganese also applies to the silicon content. If the silicon content is below about 0.5%, the transition temperature is also shifted to lower temperatures. However, silicon also has a strengthening effect above 0.5%, but at the same time is becoming increasingly brittle, which is to be avoided here for prestressing steels.
  • Niobium has the most effective influence on fine grain hardening and hardening through thermomechanical treatment, ie on the achievable increase in strength, followed by titanium and vanadium. It causes the greatest reduction in the transition temperature.
  • the niobium-containing structure results in a much larger proportion of fine-grain hardening than in hardening and thus not only a higher yield strength than structure structures alloyed with titanium or vanadium, but above all also a very favorable, low transition temperature.
  • Niobium reduces the ferrite grain size to a particularly large extent.
  • the high ratio of fine grain hardening to hardening in the structure with the addition of niobium is therefore an essential reason for the preference for niobium.
  • Niobium causes the additional hardening effect of increasing manganese contents even when pearlite is low.
  • Vanadium, like niobium forms precipitates of special carbides which, on the one hand, contribute to fine grain formation and hardening and, on the other hand, to precipitation hardening and thus significantly increase strength. Vanadium, like niobium, thus helps to control the austenite grain size by incorporating fine precipitates "in the austenite structure, which inhibits grain growth. Vanadium also contributes to solid solution strengthening like niobium, but both are insoluble in ferrite. Their excretion in ferrite The carbides and nitrides of vanadium and niobium have face-centered cubic lattice, are isomorphic and therefore completely miscible and, unlike titanium, do not contribute to the formation of sulfide.
  • vanadium has the greatest influence on the formation of a fine ferrite grain size and has an additional increase in the yield point, just like niobium, as does dissolved vanadium, by delaying the austenite conversion, this fine grain effect and hardening.
  • the delay in the austenite recrystallization is very much favored by alloying small amounts of molybdenum into the microalloyed, low-pearlite structure, whereby the - Conversion is shifted to lower temperatures.
  • this possibility is enhanced by an even deeper one Final rolling temperature used, whereby an even more fine-grained structure is achieved while improving the transition temperature.
  • alloying molybdenum and the resulting possibility of the i - - r conversion shift to lower temperatures it is also additionally possible to make full use of the considerable strengthening properties of copper.
  • both hardening mechanisms act both through the precipitation of mixed crystals and through the formation of carbonitrides, particularly at temperatures between 650 and 550 ° C.
  • Copper is used for the purpose envisaged here because of its two advantages. Firstly because of its strong hardening effect through hardening. Secondly, because of its strong corrosion-inhibiting effect.
  • the corrosion-inhibiting effect of copper can be used particularly well in high-strength structural structures produced with thermomechanical treatment, because at the low final rolling temperatures, which at the same time also lead to the highest strength increases, the element copper simultaneously with the
  • the precipitation-hardening elements used here between 650 and 550 ° C., in addition to its corrosion-inhibiting effect, also act as a precipitation-hardening element.
  • rapid cooling from the Jf ⁇ area At approximately 840 ° C., about 2% copper can be dissolved in low-pearlite structures and the thermomechanical treatment already provided here.
  • a copper-rich, face-centered mixed crystal in the form of incoherent, spherical particles then separates out, which leads, from a certain particle size, to a considerable precipitation hardness effect due to the bypass mechanism.
  • niobium, micro-alloyed structures and at the same time a low proportion of pearlite and a high copper content both hardening mechanisms take effect through the precipitation of mixed crystals and carbonitrides.
  • a nickel content of up to 1% must be added to the copper-alloyed structure in order to prevent the solder fragility caused by copper.
  • Aluminum which produces this effect via aluminum nitride, is primarily the microalloying elements niobium and vanadium, which have a comparable effect via their carbides, nitrides or carbonitrides.
  • the lowest possible pusher furnace temperature is essential for preventing or restricting the re-dissolution of such precipitates when heating before rolling.
  • the most favorable conditions for preventing the sharp increase in grain growth when reheating for rolling show higher aluminum contents.
  • Aluminum also contributes to solid solution strengthening.
  • the sudden grain growth before heating for rolling is also increased by nitrogen to higher temperatures of around 1150 ° C.
  • An increased nitrogen content also makes an important contribution to increasing the strength by increasing the nitride content. Particularly when vanadium is present, the yield strength increases significantly. This also increases the tensile strength, so that an increase in the yield strength ratio from 70% to 90%, which is particularly important for prestressing steels, is brought about.
  • the phosphorus content must remain limited, although a higher content would increase the yield strength, but at the same time the steel becomes very brittle.
  • Combined oxygen blowing / inert gas flushing makes it possible to lower the phosphorus content and largely prevent its embrittling effect. A corresponding reduction in the phosphorus content is also possible with ladle metallurgy.
  • the sulfur content plays a decisive role in the anisotropy of toughness, the most important factor influencing their cold formability for prestressing steels.
  • a lower sulfur content i.e. a reduced number of sulfide inclusions improves the toughness considerably with regard to constriction of fracture, a property that is particularly important for prestressing steels.
  • the reduction in the sulfide length is particularly effective for a more favorable constriction of the fracture.
  • a strong desulfurization can be achieved by the additions that are usual in ladle metallurgy.
  • titanium in contrast to niobium and vanadium, it participates in the formation of sulfide. On the other hand, it first binds all nitrogen to nitrides, TiN, and then sulfur to a titanium carbosulfide, Ti ⁇ C-S-. For both reasons, titanium is not taken into account here since, among other things, the effect of one of the austenite grain growth and that of an increase in strength in cooperation with the other microalloying elements would be eliminated by an increased nitrogen content.
  • the prestressing steels produced according to the present invention have
  • the coupling links are the most sensitive weak points for the occurrence of damage caused by the penetration of corrosion-promoting media up to the steel.
  • such coupling elements are usually arranged at too short intervals from one another.
  • the resulting high number of coupling joints results in a high number of weak points at the same time.
  • the prestressing systems are also structurally simplified and improved due to the suitability of these prestressing steels for welding, this additionally results in a significant reduction in the susceptibility to damage.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)
  • Forging (AREA)
  • Metal Extraction Processes (AREA)

Abstract

Dans un procédé de fabrication d'un acier de précontrainte présentant des qualités élevées de résistance à la traction, à la corrosion et à la rupture, on produit une trempe à grain fin ou à cristal mixte, ou par précipitations, conjointement avec un traitement thermomécanique suivi d'un durcissement à froid. Pour le traitement de durcissement, on utilise une trempe à grain fin ou à cristal mixte, ou à précipitations avec effet additionnel prononcé. Le traitement mécanique est effectué au moyen de cylindres en alliage d'acier, à grain fin, ce qui exclut la formation de martensite.
EP85905199A 1984-10-30 1985-10-30 Procede de fabrication d'un acier pour precontrainte Expired - Lifetime EP0198024B1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85905199T ATE51897T1 (de) 1984-10-30 1985-10-30 Verfahren zum herstellen von spannstaehlen.

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
CH5210/84A CH667104A5 (de) 1984-10-30 1984-10-30 Verfahren zum herstellen von spannstaehlen.
CH5210/84 1984-10-30
DE3535886 1985-10-08
DE19853535886 DE3535886A1 (de) 1985-10-08 1985-10-08 Verfahren zum herstellen von spannstaehlen

Publications (2)

Publication Number Publication Date
EP0198024A1 true EP0198024A1 (fr) 1986-10-22
EP0198024B1 EP0198024B1 (fr) 1990-04-11

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EP85905199A Expired - Lifetime EP0198024B1 (fr) 1984-10-30 1985-10-30 Procede de fabrication d'un acier pour precontrainte

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EP (1) EP0198024B1 (fr)
KR (1) KR930009973B1 (fr)
AU (1) AU4966585A (fr)
BR (1) BR8507018A (fr)
DE (1) DE3577109D1 (fr)
FI (1) FI862784L (fr)
NO (1) NO862605L (fr)
WO (1) WO1986002667A1 (fr)

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DE4224222A1 (de) * 1992-07-22 1994-01-27 Inst Stahlbeton Bewehrung Ev Baustahl, insbesondere Betonstahl und Verfahren zu seiner Herstellung
CH687879A5 (de) * 1993-12-01 1997-03-14 Met Cnam Paris Max Willy Tisch Armierungs-, Maschinen-, Apparate- und Metallbaustaehle in Feinkornguete mit stabiler Korrosionsschutzschicht.
MX9703857A (es) * 1994-11-28 1998-02-28 Max-Willy Tischhauser Procedimiento para la fabricacion de aceros de construccion de alta calidad cualitativa para armaduras, maquinas, aparatos y partes metalicas en calidad de grano fino y con capa de proteccion contra la corrosion.

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US8289224B2 (en) 2005-11-22 2012-10-16 Powerwave Technologies, Inc. Smart pole

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Publication number Publication date
FI862784A7 (fi) 1986-06-30
KR930009973B1 (ko) 1993-10-13
EP0198024B1 (fr) 1990-04-11
KR887000089A (ko) 1988-02-15
FI862784A0 (fi) 1986-06-30
WO1986002667A1 (fr) 1986-05-09
AU4966585A (en) 1986-05-15
DE3577109D1 (de) 1990-05-17
NO862605L (no) 1986-08-27
BR8507018A (pt) 1987-01-06
NO862605D0 (no) 1986-06-27
FI862784L (fi) 1986-06-30

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