Prestressed steel wire
Civil Engineering Terminology
Cold-drawn steel wire used to make the reinforcement in the tension
zone of prestressed concrete members. Generally, concrete has high
strength against compressive force, but is brittle and prone to
cracking when subjected to tensile force. Prestressed concrete is
to make the steel bars arranged in the tension zone of the
component bear a tensile force in advance to generate pretension
stress. The pre-tension stress on the steel bars reacts to the
pre-tension stress in the tension zone, which can offset or reduce
the tensile stress acting on the concrete by the external load,
thus greatly improving the ability of the tension zone to resist
tension, thereby reducing component size and saving materials. And
reduce the self-weight of the components. Due to these advantages,
prestressed concrete members have been successfully used in many
projects such as large bridges, roof trusses, crane beams,
industrial and civil precast floor slabs, railway sleepers, poles
and pipe piles, large-diameter precast pipes, and atomic energy
power stations. The production of prestressed steel wires has
developed rapidly with the widespread application of prestressed
concrete components. [
Chinese name prestressed steel wire
Foreign name: prestressing wire
Diameter 4mm, 4.8mm, 5.0mm, etc.
Treatment Process Heat Treatment and Cold Working
introduce
A general term for steel wires that are made from high-quality
high-carbon steel hot-rolled wire rods through heat treatment and
cold processing and are suitable for prestressed concrete
reinforcement requirements. The carbon content of this type of
steel wire is 0.65% to 0.85%, and the sulfur and phosphorus content
are less than 0.035%. The tensile strength of steel wire is
generally above 1470MPa, and its strength level has gradually
transitioned from 1470MPa and 1570MPa to 1670~1860MPa. The diameter
of the steel wire is above 3mm, and has gradually transitioned from
3 to 5 mm to 5 to 7 mm.
Prestressed steel wire began industrial production and application
in the 1920s. After decades of development, a series of products
with different characteristics suitable for different objects have
been formed, including cold-drawn steel wire, straightened and
tempered steel wire, low-relaxation steel wire, Galvanized steel
wire and scored steel wire, etc. These products and the prestressed
steel strands made of them have become the most widely used
prestressed steel varieties in the world. [2]
Cold drawn steel wire
It is a smooth round steel wire drawn from high carbon steel
hot-rolled circular wire rods after being quenched by lead
solution. Since it has not been straightened and tempered, its
elongation is low. Steel wire is delivered in rolls with diameters
ranging from 500 to 1000mm. Mostly used in railway sleepers and
concrete pressure water pipes. The diameter of cold-drawn steel
wire produced in China is mostly 3mm, and a small amount is 4mm or
5mm. During production, the steel grade and wire rod diameter are
selected according to the finished product specifications and
performance requirements. Lead solution quenching is performed
before drawing. The wire temperature is 890~930ºC and the lead
temperature is 460~500ºC. After isothermal quenching, the strength
increases to 1080~1180MPa, and the metallographic structure
transforms into a sorbite structure with excellent comprehensive
properties. In order to ensure the surface quality of the finished
product and facilitate drawing, the quenched wire rod needs to
undergo processes such as pickling, phosphating or coating.
Straightening and tempering steel wire
Cold drawn steel wire is made by straightening and tempering. The
straightening and tempering temperature is 460~500ºC, and its main
function is to eliminate the internal stress generated during
drawing. Compared with cold drawn steel wire, the yield strength of
straightened and tempered steel wire is increased, and the
ductility and stress relaxation properties are improved. The
product is supplied in large coils with a coil diameter of 1.5 to
2m. It has good straightness after uncoiling, can be constructed as
a single piece or in bundles, and is widely used to manufacture
various types of prestressed concrete components.
low relaxation wire
Cold-drawn steel bars are stabilized (that is, tempered under
tension) and named for their ability to reduce stress relaxation.
Stress relaxation is an important characteristic of prestressed
steel, that is, the stress loss of the tension element while
maintaining a constant length. Its magnitude is expressed as the
percentage of stress loss to the initial stress, which is called
the relaxation rate. In engineering applications, the stress
relaxation loss of prestressed steel accounts for a considerable
proportion of the total prestress loss of structural components.
Therefore, reducing the relaxation rate through stability treatment
is an effective method to improve the performance of steel wires.
When performing stability treatment, the tension is 0.4~0.5σb, and
the tempering temperature is controlled between 350~400ºC. Because
the steel wire generates a tiny strain of 0.9% to 1.3% under
thermal tension, its ability to prevent dislocation transfer under
the action of external forces is improved, which is manifested in
that the elastic limit and yield strength of the steel wire are
significantly increased, and the stress relaxation rate is reduced
to 1/3~1/4 of straight tempered steel wire. When used under the
same conditions, the residual stress in the prestressed tendons can
be increased by 10% to 15%. Therefore, in the past ten years, the
production and application of low-relaxation steel wires have made
great progress.
galvanized steel wire
The hot-dip galvanizing process is used to coat the surface of the
prestressed steel wire with a zinc layer of 250g/m2~350g/m2. Since
prestressed steel wire is cold-worked steel with high strength, its
surface is easily damaged and is more sensitive to media corrosion
and stress corrosion than ordinary carbon steel. In particular, the
steel wire has a small cross-sectional area and has been working
under high stress for a long time. It is affected by factors such
as the material properties, density, defects, condensation water,
cracks under stress, and the use environment of the structure of
the wrapped concrete, resulting in stress. There is a great risk of
failure of prestressed components due to corrosion and cracking.
The galvanized layer can effectively protect the steel wire matrix.
Galvanized steel wire is suitable for engineering structures with
serious corrosion such as bridge cables and sewage pools.
Scored wire
Products made by pressing regular convex ribs or pits on the
surface of smooth steel wire. Notching can improve the bonding
performance between prestressed steel wires and concrete, and is
mainly suitable for prestressed structural components constructed
by the pre-tensioning method.ZHENGDE Prestressed steel wire is a high-strength steel, widely
used in construction, bridges, tunnels, water conservancy projects
and other fields. It has excellent mechanical properties and
durability, and can effectively improve the bearing capacity and
seismic performance of structures.
The material of the prestressed steel wire is mainly high-strength
steel wire, and steel wires such as SWRH82B and SWRH77B are usually
used. These steel wires have the characteristics of high strength,
high toughness, high durability, etc., can withstand large tensile
and bending forces, and also have good corrosion resistance and
fatigue resistance.
The manufacturing process of prestressed steel wire mainly includes
drawing, steel wire stranding, prestressing processing and other
links. During the drawing process, the steel wire is drawn and
annealed multiple times to make it meet the requirements of high
strength and high toughness. In the wire stranding process,
multiple steel wires are twisted into one prestressed steel wire to
improve its bearing capacity and seismic performance. During the
prestressing process, the prestressed steel wire is tensioned to a
certain level of prestressing, so that it generates compressive
stress in the structure, thereby improving the bearing capacity and
seismic performance of the structure.
GB | ASTM | JIS | DIN | NF | BS | OCT | ISO |
65 | 1065 | | Ck67 | XC65 | 060A67 | 65 | TypeDC,SC |
70 | 1070 | | | XC70 | 070A72 | 70 | TypeDC,SC |
85 | 1086 | SUP3 | Ck85 | XC85 | 060A86 | 85 | TypeDC,SC |
65Mn | 1066 | | | | 080A67 | 65Γ | |
55Si2Mn | 9255 | | 54SiCr6 | 56Si7 | Z51A58 | 55C2 | 56SiCr7 |
55Si2MnB | | | | | | | |
55SiMnVB | | | | | | | |
60Si2Mn | 9260 | SUP6,SUP7 | 60SiCr7 | 60Si7 | Z51A60 | 60C2 | 61SiCr7 |
60Si2MnA | | | | | | 60C2A | |
60Si2CrA | 9254 | SUP12 | | | | 60C2XA | 55SiCr63 |
60Si2CrVA | | | | | | 60C2XΦA | |
55CrMnA | 5155 | SUP9 | 55Cr3 | 55Cr3 | 525A58 | | 55Cr3 |
60CrMnA | 51605 | SUP9A | | | 525A60 | | |
60CrMnBA | 51B60 | SUP11A | | | | 55XΓP | 60CrB3 |
60CrMnMoA | 4161 | SUP13A | | 60CrMo4 | 705A60 | | 60CrMo33 |
50CrVA | 6150 | SUP10A | 50CrV4 | 51CrV4 | 735A51 | 50CrΦA | 51CrV4 |
30W4Cr2VA | | | | | | | |
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Shandong Zhengde Metal Manufacturing Co., Ltd. is a production and sales company integrating hot-rolled steel
coils, cold-rolled steel coils, galvanized steel coils,
color-coated steel coils, section steel, steel pipes, steel wires,
metal mesh, stainless steel, aluminum, copper and other metal
products integrated large enterprises. Five production and sales
bases have been formed in Binzhou, Liaocheng, Wuxi, Tianjin, Jinan
and Tai'an, with more than 100 production lines, 4 nationally
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