The invention relates to a turnout rail production technology, in particular to a deeply-hardened-surface turnout rail with high degree of undercooling and the preparation method thereof. The invention aims to solve the technical problem by providing a deeply-hardened-surface turnout rail with high degree of undercooling featured in even hardness distribution and a deeply hardened surface layer and the preparation method thereof. The method is described as follows: feeding molten iron for converter smelting.fwdarw.furnace rear argon blowing station.fwdarw.LF refining.fwdarw.RH vacuumization.fwdarw.casting steel blanks.fwdarw.slow cooling in the slow cooling pit.fwdarw.austenitic homogenization.fwdarw.rail rolling.fwdarw.heat treatment; in the converter smelting process, adding 0.2-0.3% Cr, 0.04-0.06 V and 0.75-0.80% C; the heat treatment process is divided into two cooling stages. The turnout rail prepared with the method described in the invention has a deeper deeply-hardened surface layer; the hardness is distributed more evenly, the anti-contact fatigue performance is higher and the resistance to wearing is ideal.

The invention relates to a turnout rail production technology, in particular to a deeply-hardened-surface turnout rail with high degree of undercooling and the preparation method thereof. The invention aims to solve the technical problem by providing a deeply-hardened-surface turnout rail with high degree of undercooling featured in even hardness distribution and a deeply hardened surface layer and the preparation method thereof. The method is described as follows: feeding molten iron for converter smelting.fwdarw.furnace rear argon blowing station.fwdarw.LF refining.fwdarw.RH vacuumization.fwdarw.casting steel blanks.fwdarw.slow cooling in the slow cooling pit.fwdarw.austenitic homogenization.fwdarw.rail rolling.fwdarw.heat treatment; in the converter smelting process, adding 0.2-0.3% Cr, 0.04-0.06 V and 0.75-0.80% C; the heat treatment process is divided into two cooling stages. The turnout rail prepared with the method described in the invention has a deeper deeply-hardened surface layer; the hardness is distributed more evenly, the anti-contact fatigue performance is higher and the resistance to wearing is ideal.

A rail including a predetermined chemical composition is provided, in which 90 area % or greater of a metallographic structure in a cross section of a rail web portion is a pearlite structure, a minimum value of a hardness in the cross section of the rail web portion is Hv 300 or greater, and a difference between a maximum value and the minimum value of the hardness in the cross section of the rail web portion is Hv 40 or less.

A rail including a predetermined chemical composition is provided, in which 90 area % or greater of a metallographic structure in a cross section of a rail web portion is a pearlite structure, a minimum value of a hardness in the cross section of the rail web portion is Hv 300 or greater, and a difference between a maximum value and the minimum value of the hardness in the cross section of the rail web portion is Hv 40 or less.

The present disclosure relates to the technical field of rails welding, and particularly to a method for optimizing microstructure of a rail welded joint, the method comprises the following steps: step 1): subjecting a rail web area of a to-be-cooled welded joint which is obtained by flash butt welding to an accelerated cooling by means of an accelerated cooling device and by using compressed air as a cooling medium, measuring and monitoring temperature of a central position of the rail web of the welded joint while cooling; step 2): stopping the accelerated cooling when the temperature of the central position of the rail web drops to a preset temperature, then placing the welded joint in air and naturally cooling to room temperature, wherein the rail is a pearlite rail having a carbon content of 0.6-0.9 wt %.

The present disclosure relates to the technical field of rails welding, and particularly to a method for optimizing microstructure of a rail welded joint, the method comprises the following steps: step 1): subjecting a rail web area of a to-be-cooled welded joint which is obtained by flash butt welding to an accelerated cooling by means of an accelerated cooling device and by using compressed air as a cooling medium, measuring and monitoring temperature of a central position of the rail web of the welded joint while cooling; step 2): stopping the accelerated cooling when the temperature of the central position of the rail web drops to a preset temperature, then placing the welded joint in air and naturally cooling to room temperature, wherein the rail is a pearlite rail having a carbon content of 0.6-0.9 wt %.

There are provided an apparatus for cooling a rail and a method for manufacturing a rail, capable of inexpensively manufacturing a rail with high hardness and high toughness. The apparatus for cooling a rail, configured to jet a cooling medium to the head portion and foot portion of a rail in an austenite temperature range to forcibly cool the rail, includes: a first cooling unit including plural first cooling headers configured to jet the cooling medium as gas to the head top face and head side of the head portion, and first driving units configured to move at least one first cooling header of the plural first cooling headers to change the jet distance of the cooling medium jetted from the first cooling header; and a second cooling unit including a second cooling header configured to jet the cooling medium as gas to the foot portion.

There are provided an apparatus for cooling a rail and a method for manufacturing a rail, capable of inexpensively manufacturing a rail with high hardness and high toughness. The apparatus for cooling a rail, configured to jet a cooling medium to the head portion and foot portion of a rail in an austenite temperature range to forcibly cool the rail, includes: a first cooling unit including plural first cooling headers configured to jet the cooling medium as gas to the head top face and head side of the head portion, and first driving units configured to move at least one first cooling header of the plural first cooling headers to change the jet distance of the cooling medium jetted from the first cooling header; and a second cooling unit including a second cooling header configured to jet the cooling medium as gas to the foot portion.

A rail has excellent fatigue crack propagation resistance characteristics, wherein the rail has a component composition including C: 0.80 to 1.30 mass %, Si: 0.10 to 1.20 mass %, Mn: 0.20 to 1.80 mass %, P: not more than 0.035 mass %, S: 0.0005 to 0.012 mass %, Cr: 0.20 to 2.50 mass % and the remainder being Fe and inevitable impurities and satisfying CP represented by equation (1) being not more than 2500:

CP=X/R.sub.A  (1) and

X={(10×[% C])+([% Si]/12)+([% Mn]/24)+([% Cr]/21)}.sup.5  (2),

where [% Y] is content of an element Y (mass %), and R.sub.A is a prior austenite grain size (μm).

A rail has excellent fatigue crack propagation resistance characteristics, wherein the rail has a component composition including C: 0.80 to 1.30 mass %, Si: 0.10 to 1.20 mass %, Mn: 0.20 to 1.80 mass %, P: not more than 0.035 mass %, S: 0.0005 to 0.012 mass %, Cr: 0.20 to 2.50 mass % and the remainder being Fe and inevitable impurities and satisfying CP represented by equation (1) being not more than 2500:

CP=X/R.sub.A  (1) and

X={(10×[% C])+([% Si]/12)+([% Mn]/24)+([% Cr]/21)}.sup.5  (2),

where [% Y] is content of an element Y (mass %), and R.sub.A is a prior austenite grain size (μm).