IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0913509
(2001-08-15)
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우선권정보 |
FR-0001777 (1999-02-15); FR-0003955 (1999-03-30) |
국제출원번호 |
PCT/FR00/00357
(2000-02-14)
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국제공개번호 |
WO00/48199
(2000-08-17)
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발명자
/ 주소 |
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출원인 / 주소 |
|
대리인 / 주소 |
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인용정보 |
피인용 횟수 :
19 인용 특허 :
4 |
초록
▼
The present invention relates to a method for making flat, thin elements which consist of: producing a zirconium alloy blank also containing, besides the inevitable impurities, 0.8 to 1.3% of niobium, 1100 to 1800 ppm of oxygen, and 10 to 35 ppm of sulfur; carrying out a β hardening and hot rolling
The present invention relates to a method for making flat, thin elements which consist of: producing a zirconium alloy blank also containing, besides the inevitable impurities, 0.8 to 1.3% of niobium, 1100 to 1800 ppm of oxygen, and 10 to 35 ppm of sulfur; carrying out a β hardening and hot rolling to obtain a blank and performing on it at least three cold rolling passes with intermediate annealing heat treatments. One of the intermediate heat treatments is performed for a duration of at least 5 hours at a temperature less than 560° C. and all the optional treatments subsequent to the long treatment are carried out at a temperature of less than 620° C. for not more than 15 minutes.
대표청구항
▼
The present invention relates to a method for making flat, thin elements which consist of: producing a zirconium alloy blank also containing, besides the inevitable impurities, 0.8 to 1.3% of niobium, 1100 to 1800 ppm of oxygen, and 10 to 35 ppm of sulfur; carrying out a β hardening and hot rolling
The present invention relates to a method for making flat, thin elements which consist of: producing a zirconium alloy blank also containing, besides the inevitable impurities, 0.8 to 1.3% of niobium, 1100 to 1800 ppm of oxygen, and 10 to 35 ppm of sulfur; carrying out a β hardening and hot rolling to obtain a blank and performing on it at least three cold rolling passes with intermediate annealing heat treatments. One of the intermediate heat treatments is performed for a duration of at least 5 hours at a temperature less than 560° C. and all the optional treatments subsequent to the long treatment are carried out at a temperature of less than 620° C. for not more than 15 minutes. the average grain diameter of the dominant phase is no greater than 10 μm. 4. A steel sheet according to claim 1, wherein the volume fraction of the ferrite is at least 40%. 5. A steel sheet according to claim 1, wherein the value of the tensile strength×total elongation is at least 20,000 MPa %. 6. A method for producing a press formable high-strength hot-rolled steel sheet with high flow stress during dynamic deformation where the microstructure of the steel sheet in its final form is a composite microstructure of a mixture of ferrite and/or bainite, either of which is the dominant phase, and a third phase including retained austenite at a volume fraction between 3% and 50%, wherein the difference between the static tensile strength σs when deformed in a strain rate range of 5×10-4-5×10-3(l/s) after pre-deformation at an equivalent strain of greater than 0% and less than or equal to 10%, and the dynamic tensile strength σd when deformed at a strain rate of 5×102-5×103(l/s) after said pre-deformation, σd-σs, is at least 60 MPa, the difference between the average value σdyn (MPa) of the flow stress at an equivalent strain in the range of 3-10% when deformed in a strain rate range of 5×102-5×103(l/s) and the average value σst (MPa) of the flow stress at an equivalent strain in the range of 3-10% when deformed in a strain rate range of 5×10-4-5×10-3(l/s) satisfies the inequality: (σdyn-σst)≥-0.272×TS+300 as expressed in terms of the maximum stress TS (MPa) in the static tensile test as measured in a strain rate range of 5×10-4-5×10-3(l/s), the value (M) determined by the solid solution (C) in said retained austenite and the average Mn equivalents of the steel sheet {Mneq=Mn+(Ni+Cr+Cu+Mo)/2}, defined by the equation M=678-428×(C)-33 Mneq is at least -140 and less than 70, the retained austenite volume fraction of the steel sheet after pre-deformation at an equivalent strain of greater than 0% and less than or equal to 10% is at least 2.5%, the ratio between the initial volume fraction of the retained austenite V(O) and the volume fraction of the retained austenite after pre-deformation at an equivalent strain of 10% V(10), V(10)/V(O), is at least 0.3, and the work hardening coefficient calculated from stresses at 5% and 10% of strain is at least 0.130, which is characterized in that the method comprises the steps of: continuously casting a molten metal into a slab containing, in terms of wt %, C at from 0.03% to 0.3%, either or both Si and Al at a total of from 0.5% to 3.0% with the remainder Fe as a primary component, directly hot rolling the slab, with or without slab reheating step, into a strip, completely finishing hot rolling at a temperature of Ar3-50° C. to Ar3+120° C., cooling the hot rolled strip with an average cooling rate at least 5° C./sec, and, coiling the cooled strip at a temperature of no greater than 500° C. 7. A method for producing a press formable high-strength hot-rolled steel sheet according to claim 6, wherein at the finishing temperature for said hot-rolling in a range of Ar3-50° C. to Ar3+120° C., wherein ΔT is temperature difference between temperature at start of hot rolling and the hot rolling finishing temperature, the hot rolling is carried out so that the metallurgy parameter: A satisfies inequalities (1) and (2) below, the subsequent average cooling rate in the run-out table is at least 5° C./sec, and the coiling is accomplished so that the relationship between said metallurgy parameter: A and the coiling temperature (CT) satisfies inequality (3) below: 9≤log A≤18 (1) ΔT≤21×log A-178 (2) 6×log A+312≤CT≤6 log A+392 (3). 8. A method for producing a press formable high strength cold-rolled steel sheet with high flow stress during dynamic deformation where the microstructure of the steel sheet i
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