摘要:
The invention provides a method for producing a pearlitic rail by rough hot rolling and finish hot rolling a billet. In the finish hot rolling, the billet is rolled at a rail head surface temperature in a range of not higher than 900° C. to not lower than the Ar3 transformation point or Arcm transformation point to produce a head cumulative reduction of area of not less than 20%, where the reaction force ratio of the finish rolling is not less than 1.25. The finish hot rolled rail head surface is subjected to accelerated cooling or spontaneous cooling to a temperature of 550° C. or less at a cooling rate of 2 to 30° C./seconds, thereby refining the rail head structure to attain a hardness within a predetermined range, and improving rail wear resistance and ductility.
摘要:
The invention provides a method for producing a pearlitic rail by subjecting to at least rough hot rolling and finish hot rolling a billet comprising, in mass %, C: 0.65-1.20%, Si: 0.05-2.00%, Mn: 0.05-2.00%, and a remainder of iron an unavoidable impurities, wherein the finish hot rolling is conducted by rolling at a rail head surface temperature in a range of not higher than 900° C. to not lower than Ar3 transformation point or Arcm transformation point to produce a head cumulative reduction of area of not less than 20% and a reaction force ratio of not less than 1.25, and the finish hot rolled rail head surface is subjected to accelerated cooling or spontaneous cooling to at least 550° C. at a cooling rate of 2 to 30° C./sec, thereby refining the rail head structure to attain a hardness within a predetermined range and improving rail wear resistance and ductility.
摘要:
This pearlite rail consists of a steel including: in terms of percent by mass, C: 0.65 to 1.20%; Si: 0.05 to 2.00%; Mn: 0.05 to 2.00%; P≦0.0150%; S≦0.0100%; Ca: 0.0005 to 0.0200%, and Fe and inevitable impurities as the balance, wherein a head surface portion which ranges from surfaces of head corner portions and a head top portion to a depth of 10 mm has a pearlite structure, a hardness Hv of the pearlite structure is in a range of 320 to 500, and Mn sulfide-based inclusions having major lengths in a range of 10 to 100 μm are present at an amount per unit area in a range of 10 to 200/mm2 in a cross-section taken along a lengthwise direction in the pearlite structure.
摘要:
A method of reheating a rail weld zone after rails were welded, a distance C between a reheating region P of a rail web portion 2 and a welding center Q is set to more than or equal to 0.2 times and less than or equal to three times a HAZ length Lh of the rail weld zone. A length B of the reheating region P may be more than or equal to 0.5 times and less than or equal to five times the HAZ length Lh of the rail weld zone. A height A of the reheating region P may be more than or equal to 0.2 times a height Hw of the rail web portion 2. A temperature Th reached in a reheating process at a center of the reheating region P may be higher than or equal to 400° C. and lower than or equal to 750° C.
摘要:
A method of reheating a rail weld zone after rails were welded, a distance C between a reheating region P of a rail web portion 2 and a welding center Q is set to more than or equal to 0.2 times and less than or equal to three times a HAZ length Lh of the rail weld zone. A length B of the reheating region P may be more than or equal to 0.5 times and less than or equal to five times the HAZ length Lh of the rail weld zone. A height A of the reheating region P may be more than or equal to 0.2 times a height Hw of the rail web portion 2. A temperature Th reached in a reheating process at a center of the reheating region P may be higher than or equal to 400° C. and lower than or equal to 750° C.
摘要:
Disclosed are methods of producing steel rails having a high carbon content and being excellent in wear resistance and ductility from the slabs for rails. One method involves producing a steel rail having a high content of carbon, comprising finish rolling the rail in two consecutive passes, with a reduction rate per pass of a cross-section of the rail of 2-30%, wherein the conditions of the finish rolling satisfy the following relationship: S≦800/(C×T), wherein S is the maximum rolling interval time (seconds), C is the carbon content of the steel, wherein the carbon content is 0.85-1.40 mass %, and T is the maximum surface temperature (° C.) of the rail head. Another method involves producing a steel rail with a high content of carbon, comprising: finish rolling the rail in three or more passes, with a reduction rate per pass of a cross-section of the rail of 2-30%, wherein the conditions of the finish rolling satisfy the following relationship: S≦2400/(C×T×P), wherein S is the maximum rolling interval time (seconds), C is the carbon content of the steel rail, wherein the carbon content is 0.85˜1.40 mass %, T is the maximum surface temperature (° C.) of a rail head, and P is the number of passes, which is 3 or more. In addition to above, controlled additional amounts of V, Nb, N may be added to the steel rail and/or controlled rapid cooling of the rail after rolling may be accomplished to provide further improvements.
摘要:
A heating device includes a first member having a first sheet holding face, and a second member having a second sheet holding face and disposed facing the first sheet holding face of the first member. The first and second sheet holding faces are configured to hold a sheet between the first and second sheet holding faces. The sheet has a resin surface on at least one face of the sheet. The heating device is configured to heat the sheet while the first and second sheet holding faces hold the sheet on which liquid is applied. At least one of the first and second sheet holding faces is configured to contact the resin surface of the sheet. The at least one of the first and second sheet holding faces has an uneven surface with a plurality of convex or concave portions.
摘要:
A data carrier 2 is provided with a comparator 41, a capacitor 42, a comparator operation adjustment resistor 43, a resistance voltage divider circuit 44 and a reactive-current resistor 45. The capacitor 42 is disposed between the cathode of a photo-diode (PD) 21 and the minus input terminal of the comparator 41. The comparator operation adjustment resistor 43 is disposed between the plus terminal of a primary battery 271 and the minus input terminal of the comparator 41. The resistance voltage divider circuit 44 is constituted by a series connection of voltage dividing resistors 441 and 442. One end of the resistance voltage divider circuit 44 is connected to the plus terminal of the primary battery 271. The junction between the voltage division resistor 441 and the other voltage division resistor 442 is connected to the plus input terminal of the comparator 41.
摘要:
In a hot-rolled steel sheet, an average pole density of an orientation group {100} to {223} , which is represented by an arithmetic mean of pole densities of orientations {100} , {116} , {114} , {112} , and {223} is 1.0 to 4.0 and a pole density of a crystal orientation {332} is 1.0 to 4.8, in a thickness center portion which is a thickness range of ⅝ to ⅜ from the surface of the steel sheet; an average grain size in the thickness center portion is less than or equal to 10 μm and a grain size of cementite precipitating in a grain boundary of the steel sheet is less than or equal to 2 μm; and an average grain size of precipitates containing TiC in grains is less than or equal to 3 nm and a number density per unit volume is greater than or equal to 1×1016 grains/cm3.
摘要:
A water pump has a pump section having radial impeller blades, a rotational shaft for rotating the radial impeller blades, and a motor section provided in the rear of the pump section and driving the rotational shaft. The motor section has a motor casing, a motor housed in the motor casing and rotating the rotational shaft, bearings provided on both sides of the motor interposed between them on the rotational shaft, interposed between an inner surface of the motor casing and the rotational shaft, and rotatably supporting the rotational shaft. In the motor casing, a vent hole for venting air between a motor space in which the motor is disposed in the motor casing and an outside of the motor casing is formed.