Drawing Method And Wire Produced By Said Drawing Method
The steel wire having a completely ferritic, pearlitic or ferritic-pearlitic microstructure has a weight content of carbon C such that 0.05% C<0.4% and a weight content of chromium Cr such that Cr<12%. The process for drawing the wire comprises: at least one first uninterrupted series of steps ( 400 1 - 400 m ) of drawing the wire from a diameter D to a diameter d′, at least one second uninterrupted series of steps ( 700 1 - 700 m ) of drawing the wire of diameter d′ to a diameter d, one or more intermediate steps between the first and second uninterrupted series of steps ( 400 1 - 400 m , 700 1 - 700 m ) of drawing the wire, the wire having a temperature less than or equal to 300° C. during the or each intermediate step.
1 . A process for drawing a steel wire having a completely ferritic, pearlitic or ferritic-pearlitic microstructure, wherein the wire has a weight content of carbon C such that 0.05%≦C<0.4% and a weight content of chromium Cr such that Cr<12%, the process comprising:
at least one first uninterrupted series of steps of drawing the wire from a diameter D to a diameter d′,
at least one second uninterrupted series of steps of drawing the wire of diameter d′ to a diameter d,
one or more intermediate steps between the first and second uninterrupted series of steps of drawing the wire, the wire having a temperature less than or equal to 300° C. during the or each intermediate step.
2 . The process according to claim 1 , wherein d′ is greater than or equal to 0.5 mm.
3 . The process according to claim 1 , wherein d′ is less than or equal to 2.5 mm.
4 . The process according to claim 1 , wherein the first uninterrupted series of steps of drawing the wire from the diameter D to the diameter d′ is carried out in a dry environment.
5 . The process according to claim 1 , wherein the second uninterrupted series of steps of drawing the wire from the diameter d′ to the diameter d is carried out in a wet environment.
6 . The process according to claim 1 , wherein d′ and d being expressed in mm, the true strain ε=2.In (d′/d) is such that ε′>3.
7 . The process according to claim 1 , wherein d′ and d being expressed in mm, the true strain ε=2.In (d′/d) is such that ε′≦5.
8 . The process according to claim 1 , wherein d′ and d being expressed in mm, the true strain ε=2.In (d′/d) is such that ε′≧ 3 . 5 .
9 . The process according to claim 1 , wherein d′ and d being expressed in mm, the true strain ε=2.In (d′/d) is such that ε′≦4.
10 . The process according to claim 1 , wherein D and d′ being expressed in mm, the true strain ε=2.In (D/d′) is such that ε≧2.
11 . The process according to claim 1 , wherein D and d′ being expressed in mm, the true strain ε=2.In (D/d′) is such that ε≦5.
12 . The process according to claim 1 , wherein D and d′ being expressed in mm, the true strain ε=2.In (D/d′) is such that ε≦3, preferably ε≦2.75.
13 . The process according to claim 1 , wherein D and d′ being expressed in mm, the true strain ε=2.In (D/d′) is such that ε≧3, preferably ε≧3.5.
14 . The process according to claim 1 , wherein D and d being expressed in mm, the true strain ε=2.In (D/d) is such that εT≧6.5, preferably εT≧6.75.
15 . The process according to claim 1 , wherein εT≦8.
16 . The process according to claim 1 , wherein D is greater than or equal to 4 mm.
17 . The process according to claim 1 , wherein the intermediate step or steps do not comprise a step of heating the steel beyond its austenitizing temperature.
18 . The process according to claim 1 , wherein the intermediate step or steps comprise a step of coating the wire of diameter d′ with at least one metal layer.
19 . The process according to claim 18 , wherein the step of coating the wire of diameter d′ is selected from a step of depositing a layer of an alloy of substantially pure metals, a step of depositing a first layer of a first substantially pure metal followed by a step of depositing a second layer of a second substantially pure metal, and a step of depositing a layer of a substantially pure metal.
20 . The process according to claim 19 wherein the step of coating the wire of diameter d′ comprising a step of depositing a first layer of a first substantially pure metal followed by a step of depositing a second layer of a second substantially pure metal, the intermediate step or steps do not comprise a step of thermal diffusion of each first and second metal respectively into the second and first layer.
21 . A steel wire of diameter d expressed in mm and having a completely ferritic, pearlitic or ferritic-pearlitic microstructure, wherein the wire has a weight content of carbon C such that 0.05%≦C<0.4%, a weight content of chromium Cr such that Cr<12% and a maximum tensile strength R, expressed in MPa, such that R≧A+910.C−600.In(d) with A=875.
22 . The wire according to claim 21 , having a weight content of carbon C such that 0.07%≦C≦0.3%.
23 . The wire according to claim 21 , wherein A=1025.
24 . The wire according to claim 21 , wherein R≧1500 MPa.
25 . The wire according to claim 21 , wherein d is greater than or equal to 0.10 mm.
26 . The wire according to claim 21 , wherein d is less than or equal to 0.40 mm.
27 . A cord comprising several wires according to claim 21 .
28 . A semi-finished element it comprises a rubber matrix in which at least one wire according to claim 21 is embedded.
29 . A tire comprising at least one wire according to claim 21 .