1-15. (canceled)
16. A steel sheet for hot press forming, comprising: by weight,
carbon (C): 0.15 to 0.35%;
silicon (Si): 0.5% or less;
manganese (Mn): 1.5 to 2.2%;
phosphorus (P): 0.025% or less;
sulfur (S): 0.01% or less;
aluminum (Al): 0.01 to 0.05%;
nitrogen (N): 50 to 200 ppm;
titanium (Ti): 0.005 to 0.05%;
tungsten (W): 0.005 to 0.1%; and
boron (B): 1 to 50 ppm,
wherein TiN: less than 3.4, where TiN is the atomic ratio of the corresponding elements, Ceq expressed by the following formula ranges from 0.48 to 0.58, and temperature Ar3 ranges from 670\xb0 C. to 725\xb0 C.
Ceq=C+Si24+Mn6+Ni40+Cr5+V14\u2003\u2003Formula
where C, Si, Mn, Ni, Cr and V indicate the contents (wt %) of the respective elements.
17. The steel sheet of claim 16, further comprising at least one selected from the group consisting of by weight: niobium (Nb): 0.005 to 0.1%; vanadium (V): 0.005 to 0.1%; copper (Cu): 0.1 to 1.0%; and nickel (Ni): 0.05 to 0.5%.
18. The steel sheet of claim 16, wherein the steel sheet has a microstructure having ferrite and pearlite.
19. A method of manufacturing a hot rolled steel sheet for hot press forming, comprising:
heating a steel slab to a temperature from 1150\xb0 C. to 1250\xb0 C., the steel slab having a composition of, by weight, carbon (C): 0.15 to 0.35%, silicon (Si): 0.5% or less, manganese (Mn): 1.5 to 2.2%, phosphorus (P): 0.025% or less, sulfur (S): 0.01% or less, aluminum (Al): 0.01 to 0.05%, nitrogen (N): 50 to 200 ppm, titanium (Ti): 0.005 to 0.05%, tungsten (W): 0.005 to 0.1%, and boron (B): 1 to S0 ppm, wherein TiN: less than 3.4, where TiN is the atomic ratio of the corresponding elements, Ceq expressed by the following formula ranges from 0.48 to 0.58, and temperature Ar3 ranges from 670\xb0 C. to 725\xb0 C.; and
rolling the heated steel slab via a roughing mill process and a finishing mill process to form the steel sheet,
wherein the finishing mill process includes:
rolling the steel sheet above Ar3 temperature; and
cooling and coiling the steel sheet at a temperature from 600\xb0 C. to 700\xb0 C.
Ceq=IC+Si24+Mn6+Ni40+Cr5+V14
where C, Si, Mn, Ni, Cr and V indicate the contents (wt %) of the respective elements.
20. The method of claim 19, wherein the steel slab further comprises at least one selected from the group consisting of by weight, niobium (Mb) 0.005 to 0.1%; vanadium (V): 0.005 to 0.1%; copper (Cu): 0.1 to 1.0%; and nickel (Ni): 0.05 to 0.5%.
21. A method of manufacturing a cold rolled steel sheet for hot press forming, comprising:
pickling a hot rolled steel sheet, the hot rolled steel sheet having a composition of, by weight, carbon (C): 0.15 to 0.35%, silicon (Si): 0.5% or less, manganese (Mn): 1.5 to 2.2%, phosphorus (P): 0.025% or less, sulfur (S): 0.01% or less, aluminum (Al): 0.01 to 0.05%, nitrogen (N): 50 to 200 ppm, titanium (Ti): 0.005 to 0.05%, tungsten (W): 0.005 to 0.1%, and boron (B): 1 to 50 ppm, wherein TiN: less than 3.4, where TiN is the atomic ratio of the corresponding elements, Ceq expressed by the following formula ranges from 0.48 to 0.58, and temperature Ar3 ranges from 670\xb0 C. to 725\xb0 C.;
cold-rolling the pickled steel sheet to manufacture full hard steel sheet; and
continuously annealing the full hard steel sheet,
wherein, the temperature of continuous-annealing is controlled to be within a range of 750\xb0 C. to 850\xb0 C., and temperature of a following over aging section is controlled to be within a range of 450\xb0 C. to 600\xb0 C.
Ceq=C+Si24+Mn6+Ni40+Cr15+V14\u2003\u2003Formula
where C, Si, Mn, Ni, Cr and V indicate the contents (wt %) of the respective elements.
22. The method of claim 21, wherein the hot rolled steel sheet further comprises at least one selected from the group consisting of by weight: niobium (Nb); 0.005 to 0.1%; vanadium (V): 0.005 to 0.1%; copper (Cu): 0.1 to 1.0%; and nickel (Ni): 0.05 to 0.5%.
23. The method of claim 21, further comprising coating the steel sheet with zinc.
24. The method of claim 22, further comprising coating the steel sheet with zinc.
25. The method of claim 23, wherein the coating of the steel sheet with zinc includes one selected from hot-dip galvanizing, galvannealing, zinc or zinc-iron electroplating.
26. The method of claim 24, wherein the coating of the steel sheet with zinc includes one selected from hot-dip galvanizing, galvannealing, zinc or zinc-iron electroplating.
27. A method of manufacturing an aluminum coated steel sheet for hot press forming, comprising:
pickling a hot rolled steel sheet, the hot rolled steel sheet having a composition of, by weight, carbon (C): 0.15 to 0.35%, silicon (Si): 0.5% or less, manganese (Mn): 1.5 to 2.2%, phosphorus (P): 0.025% or less, sulfur (S): 0.01% or less, aluminum (Al): 0.01 to 0.05%, nitrogen (N): 50 to 200 ppm, titanium (Ti): 0.005 to 0.05%, tungsten (W): 0.005 to 0.1%, and boron (B): 1 to 50 ppm, wherein TiN: less than 3.4, where TiN is the atomic ratio of the corresponding elements, Ceq expressed by the following formula ranges from 0.48 to 0.58, and temperature Ar3 ranges from 670\xb0 C. to 725\xb0 C.;
cold-rolling the pickled steel sheet to manufacture full hard steel sheet;
annealing the full hard steel sheet at a temperature from 750\xb0 C. to 850\xb0 C.; and dipping the annealed steel sheet in a hot aluminum or aluminum alloy bath so as to cool the coated steel sheet to room temperature at a cooling rate from 5\xb0 C.sec to 15\xb0 C.sec.
Ceq=C+Si24+Mn6+Ni40+Cr5+V14\u2003\u2003Formula
where C, Si, Mn, Ni, Cr and V indicate the contents (wt %) of the respective elements.
28. The method of claim 27, wherein the aluminum coated steel sheet further comprises at least one selected from the group consisting of by weight: niobium (Nb): 0.005 to 0.1%; vanadium (V): 0.005 to 0.1%; copper (Cu): 0.1 to 1.0%; and nickel (Ni): 0.05 to 0.5%.
29. A method of manufacturing parts, comprising:
preparing a blank made of a steel sheet for hot press forming, the steel sheet having a composition of, by weight, carbon (C): 0.15 to 0.35%, silicon (Si): 0.5% or less, manganese (Mn): 1.5 to 2.2%, phosphorus (P): 0.025% or less, sulfur (S): 0.01% or less, aluminum (Al): 0.01 to 0.05%, nitrogen (N): 50 to 200 ppm, titanium (Ti): 0.005 to 0.05%, tungsten (W): 0.005 to 0.1%, and boron (B): 1 to 50 ppm, wherein TiN: less than 3.4, where TiN is the atomic ratio of the corresponding elements, Ceq expressed by the following formula ranges from 0.48 to 0.58, and temperature Ar3 ranges from 670\xb0 C. to 725\xb0 C.;
heating the blank at a temperature of 820\xb0 C. to 950\xb0 C.;
maintaining the heated blank for 60 seconds or more, and extracting the maintained blank;
transferring the extracted blank into a prepared die, and performing the hot press forming; and
cooling hot press formed part to a temperature of 200\xb0 C. or less at a cooling rate of 20\xb0 C.sec or more in the die.
Ceq=C+Si24+Mn6+Ni40+Cr5+V14
where C, Si, Mn, Ni, Cr and V indicate the contents (wt %) of the respective elements.
30. A method of manufacturing parts, comprising:
preparing a blank or a tube made of a steel sheet for post-heat treatment, the steel sheet having a composition of, by weight, carbon (C): 0.15 to 0.35%, silicon (Si): 0.5% or less, manganese (Mn): 1.5 to 2.2%, phosphorus (P): 0.025% or less, sulfur (S): 0.01% or less, aluminum (Al). 0.01 to 0.05%, nitrogen (N): 50 to 200 ppm, titanium (Ti): 0.005 to 0.05%, tungsten (W): 0.005 to 0.1%, and boron (B): 1 to 50 ppm, wherein TiN: less than 3.4, where TiN is the atomic ratio of the corresponding elements, Ceq expressed by the following formula ranges from 0.48 to 0.58, and temperature Ar3 ranges from 670\xb0 C. to 725\xb0 C.;
cold-forming the prepared blank or tube into a shape of the part:
heating the manufactured part at a temperature of 820\xb0 C. to 950\xb0 C.;
maintaining the heated part for 60 seconds or more, and extracting the maintained part; and
cooling the extracted part to a temperature of 200\xb0 C. or less at a cooling rate of 20\xb0 C.sec or more.
Ceq=C+Si24+Mn6+Ni40+Cr5+V14
where C, Si, Mn, Ni, Cr and V indicate the contents (wt %) of the respective elements.
31. The method of claim 29, wherein the steel sheet for forming further comprises at least one selected from the group consisting of by weight: niobium (Nb): 0.005 to 0.1%; vanadium (V): 0.005 to 0.1%; copper (Cu): 0.1 to 1.0%; and nickel (Ni): 0.05 to 0.5%.
32. The method of claim 30, wherein the steel sheet for forming further comprises at least one selected from the group consisting of by weight: niobium (Nb): 0.005 to 0.1%; vanadium (V): 0.005 to 0.1%; copper (Cu): 0.1 to 1.0%; and nickel (Ni): 0.05 to 0.5%.
33. A structural part for a motor vehicle, which is manufactured by hot press forming, and post-heat treatment after cold forming, in which:
the steel sheet has a composition of, by weight, carbon (C): 0.15 to 0.35%, silicon (Si): 0.5% or less, manganese (Mn): 1.5 to 2.2%, phosphorus (P): 0.025% or less, sulfur (S): 0.01% or less, aluminum (Al): 0.01 to 0.05%, nitrogen (N): 50 to 200 ppm, titanium (Ti): 0.005 to 0.05%, tungsten (W): 0.005 to 0.1%, and boron (B): 1 to 50 ppm, wherein TiN: 3.4 less than less, where TiN is the atomic ratio of the corresponding elements, Ceq expressed by the following formula ranges from 0.48 to 0.58, and temperature Ar3 ranges from 670\xb0 C. to 725\xb0 C.; and
a final microstructure of the steel sheet includes, by area fraction, martensite of 90% or more, and the balance of at least one selected from bainite and ferrite.
Ceq=C+Si24+Mn6+Ni40+Cr5+V14\u2003\u2003Formula
where C, Si, Mn, Ni, Cr and V indicate the contents (wt %) of the respective elements.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A recording apparatus comprising:
a recording head that ejects liquid onto a recording medium;
a transporting device that transports the recording medium along a supporting surface; and
a preheating device that preheats the recording medium to the upstream side of the recording head in a transporting direction of the recording medium,
wherein the preheating device includes a heating section that increases the amount of heat per unit time which is applied to the recording medium, as the recording medium is moved toward the downstream side in the transporting direction.
2. The recording apparatus according to claim 1,
wherein the heating section includes a plurality of heating sources arranged along the supporting surface, with gaps decreasing toward the downstream side in the transporting direction.
3. The recording apparatus according to claim 1,
wherein the heating section includes:
a supporting member that has the supporting surface and a plurality of bending portions that bend along a virtual curved line having the center of curvature at the opposite side to where the supporting surface is provided such that the gaps decrease toward the downstream side in the transporting direction; and
an indirect-heating device that heats the recording medium on the supporting surface by heating the supporting member.
4. The recording apparatus according to claim 1,
wherein the heating section includes a temperature control unit that increases the temperature of the plurality of heating sources arranged along the supporting surface, toward the downstream side in the transporting direction.