【Technology】Performance of ultra-low-speed drawing of high-carbon steel wire
Japanese science and technology workers to study the drawing speed of 0.05 m/min, high-carbon steel wire temperature below 50 ℃, steel wire tensile strength and torsion value, section shrinkage changes. Test using a lead bath quenching Ф5.6 mm high-carbon steel coil, w (C) = 0.75%, w (Si) = 0.24%, w (Mn) = 0.50%, the test program 4, the first 3 with 2 sets of continuous drawing machine, the fourth with a universal testing machine. 2 sets of continuous drawing machine in the first process: Ф5.6-4.75-4.05-3.45-2.94-2.5mm, the second process: Ф2.5mm, the second process: Ф2.5mm, the second process: Ф2.5mm, the second process: Ф2.5mm, the second process: Ф2.5mm, the second process: Ф2.5mm. 2 process: Ф2.5-2.14-1.83-1.56-1.34mm. program 1 in the 2 sets of wire drawing machine last channel drawing speed were 50, 58m/min; program 2 in the 2 sets of wire drawing machine last channel drawing speed were 180, 210m/min; program 3 in the 2 sets of wire drawing machine last channel drawing speed were 300, 350m/min; program 4 in the various channels In program 3, the last drawing speed of two drawing machines is 300,350m/min respectively; in program 4, the drawing speed of each pass is 0.05m/min.
The tensile strength and drawing limit under different program drawing conditions are different. Program 1 were used Ф5.6,4.75,4.05,3.45,2.94,2.5,2.14,1.83,1.56mm tensile strength of 1250,1430,1600,1800,1900,2100,2200,2400,2550MPa; Program 2 and Program 3 tensile strength is slightly lower than that of Program 1, total Compression rate of 85.3%, Ф 2.14mm are fractured; Program 4 using Ф5.6, 4.75, 4.05, 3.45, 2.94, 2.5, 2.14, 1.83, 1.56, 1.34 mm, different diameters of the steel wire tensile strength obtained were 1250,1400, 1500, 1580, 1700, 1820, 1980, 2170 1980,2170,2370,2550MPa.
The torsion value of the wire under different program drawing conditions is different, and the length of the test wire is 100 times the diameter. Program 4 from Ф4.75m to 1.56mm wire torsion value of about 50, drawing to 1.34mm, the wire torsion value dramatically reduced to about 30; program 1 conditions, using Ф4.75, 4.05, 3.45, 2.94, 2.5, 2.14, 1.83 mm steel wire torsion value of 50, 40, 26, 30, 28, 35, 28, respectively; programs 2 and Scheme 3 conditions, from 4.75 mm to 2.14 mm diameter wire torsion value of 25.
The section shrinkage of the wires under different scheme drawing conditions was different. Program 4 total compression in less than 92.2% of the section shrinkage of about 50%, 94.2% of the section shrinkage decreased to 37%; Program 1 total compression in less than 89.2% of the section shrinkage of about 45%, 92.2% of the section shrinkage dropped sharply to 5%; Program 2, Program 3 total compression in less than 89.2% of the section shrinkage of about 40%.
Different programs will be drawn to 2.5mm, to program 3 of the final pass wire line speed 300m/min production of steel wire torsion value as a benchmark, the wire line speed of 180, 50, 0.05m/min production of steel wire torsion value of program 3, respectively, 1.0, 1.2, 2.0 times.
General wire torsion fracture initial position in the surface, drawing fracture initial position in the heart, continuous drawing process at high speed under the surface of the steel wire strain aging brittle fracture is caused by the surface and the frictional heat of the drawing die, low-speed drawing can effectively reduce the brittle fracture. Steel wire pulling brittle fracture section shrinkage is mainly affected by the toughness of the steel wire heart.