A method of making a high strength base-hardened tee rail and the tee rail produced by the method. The method includes the steps of providing a carbon steel tee rail, the steel tee rail provided at a temperature between 700 and 800° C.; and cooling the steel tee rail at a cooling rate that the temperature in ° C. of the surface of the base of said steel tee rail, is maintained in a region between: an upper cooling rate boundary plot defined by an upper line connecting xy-coordinates (0 s, 800° C.), (80 s, 675° C.), (110 s, 650° C.) and (140 s, 663° C.); and a lower cooling rate boundary plot defined by a lower line connecting xy-coordinates (0 s, 700° C.), (80 s, 575° C.), (110 s, 550° C.) and (140 s, 535° C.).

A cooling device for a cooling operation of a flat metallic product is provided, the cooling device being located in an essentially vertical path including: a tank filled with a coolant bath defining a coolant surface, the tank including at least two openings, one on the upper surface and one on the bottom surface wherein the flat metallic product can pass through, the opening on the bottom surface being equipped with a sealing mean, two series of projecting devices, oriented essentially horizontally, on two opposite tank sides, the projecting devices being immersed in the coolant bath, each series of projecting devices having an uppermost projecting device being defined as the closest projecting device to the coolant surface, at least the uppermost projecting device on both sides being downwardly inclined of an angle of 20° to 40° compared to the horizontal.

A method and arrangement for manufacturing hot dip galvanized rolled high strength steel product is presented. The method comprises providing a rolled steel product, heating and annealing the rolled steel product for creating a layer of iron oxide on the surface of the rolled steel product, cooling the rolled steel product, having the iron oxide layer, in a first cooling step to a temperature in a temperature range of 560-600° C. and holding for 3-10 seconds, quenching said rolled steel product, covered with the layer of iron oxide, in a second cooling step by immersing it into a zinc bath comprising aluminium and having a temperature between 440-450° C. for 1-5 seconds and cooling the rolled steel product in a third cooling step to room temperature. An arrangement for implementing the method is also presented.

A method for manufacturing a bainite high-strength seamless steel tube, comprising the following steps: smelting, manufacturing a billet, heating, perforating, rolling, stretch reducing or sizing to obtain tube, and cooling. In the cooling step, the quenching starting temperature is controlled to be at least 20° C. higher than the Ar3 temperature of the steel grade; the finish cooling temperature is controlled to be within a range between T1 and T2, where T1=519-423 C-30.4Mn, T2=780-270 C-90Mn, and the units of the T1 and the T2 are ° C.; in the formulas, C and Mn respectively represent the mass percents of element C and element Mn of the steel grade, the content of the element C is 0.06-0.2%, and the content of the element Mn is 1-2.5%; the cooling rate is controlled to be 15-80° C./s; and the finished product of the bainite high-strength seamless steel tube is directly obtained after the cooling step. The manufacturing of a bainite high-strength seamless steel tube using the method requires neither the addition of precious alloying elements nor the subsequent heat treatment. Therefore the production costs are low.

A method for manufacturing a bainite high-strength seamless steel tube, comprising the following steps: smelting, manufacturing a billet, heating, perforating, rolling, stretch reducing or sizing to obtain tube, and cooling. In the cooling step, the quenching starting temperature is controlled to be at least 20° C. higher than the Ar3 temperature of the steel grade; the finish cooling temperature is controlled to be within a range between T1 and T2, where T1=519-423 C-30.4Mn, T2=780-270 C-90Mn, and the units of the T1 and the T2 are ° C.; in the formulas, C and Mn respectively represent the mass percents of element C and element Mn of the steel grade, the content of the element C is 0.06-0.2%, and the content of the element Mn is 1-2.5%; the cooling rate is controlled to be 15-80° C./s; and the finished product of the bainite high-strength seamless steel tube is directly obtained after the cooling step. The manufacturing of a bainite high-strength seamless steel tube using the method requires neither the addition of precious alloying elements nor the subsequent heat treatment. Therefore the production costs are low.

A method of quenching a press hardenable steel is provided. The method includes an initial step of die quenching a part stamped within a stamping die followed by a partial quenching after the initial step of die quenching. In various methods, the press hardenable steel is a 36MnB5 grade steel and/or the initial step of die quenching is performed at a temperature of approximately 200° C.±10° C. in a die configured for 36MnB5 grade steel. At least one method further includes opening the die followed by the partial quenching, the partial quenching comprising spraying a cooling liquid onto the part to reduce a temperature of the part below approximately 130° C.±10° C., with the option of spraying to reduce the temperature of the part below approximately 100° C.±10° C.

A method of quenching a press hardenable steel is provided. The method includes an initial step of die quenching a part stamped within a stamping die followed by a partial quenching after the initial step of die quenching. In various methods, the press hardenable steel is a 36MnB5 grade steel and/or the initial step of die quenching is performed at a temperature of approximately 200° C.±10° C. in a die configured for 36MnB5 grade steel. At least one method further includes opening the die followed by the partial quenching, the partial quenching comprising spraying a cooling liquid onto the part to reduce a temperature of the part below approximately 130° C.±10° C., with the option of spraying to reduce the temperature of the part below approximately 100° C.±10° C.

An apparatus for manufacturing a rack bar includes a pre-forming machine forming a flattened portion on an outer peripheral surface of a hollow shaft member, a teeth forming machine forming rack teeth on the flattened portion, a heat treatment machine quenching the rack teeth, a first conveying machine carrying the shaft member into and from the pre-forming machine, a second conveying machine carrying the shaft member into and from the teeth forming machine, and a third conveying machine carrying the shaft member into and from the heat treatment machine. The first conveying machine, the second conveying machine, and the third conveying machine hold one end of the shaft member from a radially inner side of the shaft member. The apparatus of the rack bar are suitable for manufacturing a relatively short hollow rack bar having rack teeth formed over substantially an entire length of a shaft member.

An apparatus for manufacturing a rack bar includes a pre-forming machine forming a flattened portion on an outer peripheral surface of a hollow shaft member, a teeth forming machine forming rack teeth on the flattened portion, a heat treatment machine quenching the rack teeth, a first conveying machine carrying the shaft member into and from the pre-forming machine, a second conveying machine carrying the shaft member into and from the teeth forming machine, and a third conveying machine carrying the shaft member into and from the heat treatment machine. The first conveying machine, the second conveying machine, and the third conveying machine hold one end of the shaft member from a radially inner side of the shaft member. The apparatus of the rack bar are suitable for manufacturing a relatively short hollow rack bar having rack teeth formed over substantially an entire length of a shaft member.

Disclosed is a continuous thermal treatment line for a steel strip. The strip passes through consecutive thermal treatment chambers, is quickly cooled in at least one of the chambers by spraying liquid onto the strip, or by spraying a fluid made up of gas and liquid or spraying a combination of gas and liquid forming a mist. After quick cooling, a protective metal layer is deposited on the strip by dip coating. The cooling fluid strips iron oxides or other alloy elements contained in the steel to be treated, minimizing oxidation and reducing the oxides on the strip. Spray pressure and distance are chosen to facilitate the stripping property and the mechanical action of the sprayed fluid, reducing the layer of oxides on the strip. The temperature of the strip at the end of the cooling step is the temperature necessary for carrying out the desired treatment cycle.