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- Nachgewiesen in: USPTO Patent Grants
- Sprachen: English
- Patent Number: 11939,651
- Publication Date: March 26, 2024
- Appl. No: 17/059641
- Application Filed: May 31, 2018
- Assignees: POSCO CO., LTD (Pohang-si, KR)
- Claim: 1. An Al—Fe alloy plated steel sheet for hot press forming, the Al—Fe alloy plated steel sheet comprising: a base steel sheet comprising, by weight percentage (wt %), carbon (C): 0.1 to 0.5%, silicon (Si): 0.01 to 2.0%, manganese (Mn): 0.1 to 10%, phosphorus (P): 0.001 to 0.05%, sulfur (S): 0.0001 to 0.02%, aluminum (Al): 0.001 to 1.0%, nitrogen (N): 0.001 to 0.02%, and a balance of iron (Fe) and unavoidable impurities; an Al—Fe alloy layer disposed on the base steel sheet; and an oxide layer formed on the Al—Fe alloy layer, the oxide layer having a thickness of 2 μm or less, wherein the thickness of 2 μm or less refers to a thickness to a point having 10 wt % of oxygen concentration in an oxygen concentration profile obtained through glow discharge spectrometer (GDS) analysis, wherein the Al—Fe alloy layer comprises, by wt %, aluminum (Al): 40 to 60%, silicon (Si): 2 to 10%, and a balance of iron (Fe) and unavoidable impurities, and a fraction of an unalloyed phase is 1 area % or less, and wherein the Al—Fe alloy layer comprises: a diffusion layer disposed on the base steel sheet and constituting a layer while including Si in an amount of 0.5 to 12.0 wt %; and an intermediate layer disposed in the Al—Fe alloy layer and constituting a layer while including Si in an amount of 3.0 to 20.0 wt %, and wherein a sum of average thicknesses of the diffusion layer and the intermediate layer is 1.0 to 10 μm.
- Claim: 2. The Al—Fe alloy plated steel sheet of claim 1 , wherein the base steel sheet further comprises one or more of chromium (Cr) and molybdenum (Mo) in a total amount of 0.01 to 4.0 wt %.
- Claim: 3. The Al—Fe alloy plated steel sheet of claim 1 , wherein the base steel sheet further comprises one or more of titanium (Ti), niobium (Nb), and vanadium (V) in a total amount of 0.001 to 0.4 wt %.
- Claim: 4. The Al—Fe alloy plated steel sheet of claim 1 , wherein the base steel sheet further comprises boron (B) in an amount of 0.0001 to 0.01 wt %.
- Claim: 5. The Al—Fe alloy plated steel sheet of claim 1 , wherein the base steel sheet has a microstructure comprising, by an area fraction, 20% or less of pearlite, 10% or less of martensite, 10% or less of spheroidized carbide, and a balance of ferrite.
- Claim: 6. The Al—Fe alloy plated steel sheet of claim 1 , wherein the Al—Fe alloy layer has a thickness of 10 to 60 μm.
- Claim: 7. A hot press formed part manufactured by hot press forming a tailer welded blank, the tailer welded blank being manufactured by welding an Al—Fe alloy plated steel sheet of claim 1 to a steel sheet having a thickness or a strength different from a thickness or a strength of the Al—Fe alloyed plate steel sheet, wherein the hot press formed part has a tensile strength of 1300 MPa or more and a welding zone hardness deviation of 100Hv or less.
- Claim: 8. The hot press formed part of claim 7 , wherein a portion corresponding to the Al—Fe alloy plated steel sheet has a microstructure comprising martensite or bainite as a main phase, 30 area % or less of retained austenite, and 5 area % or less of ferrite.
- Claim: 9. A method of manufacturing a hot press formed part, the method comprising: welding an Al—Fe alloy plated steel sheet of claim 1 to a steel sheet having a thickness or a strength different from a thickness or a strength of the Al—Fe alloy plated steel sheet to form a tailer welded blank; heating the tailer welded blank to a temperate within a range of (Ae3+30° C.) to (Ae3+150° C.) at a heating rate of 1 to 1000° C./sec and then maintained for 1 to 1000 seconds to form a heated tailer welded blank; and hot press forming the heated tailer welded blank while simultaneously cooling at a cooling rate of 1 to 1000° C./sec.
- Claim: 10. The method of claim 9 , wherein the steel sheet having the strength different from that of the Al—Fe alloy plated steel sheet comprises carbon (C): 0.05 to 0.08%, silicon (Si): 0.01 to 0.4%, manganese (Mn): 0.08 to 1.7%, aluminum (Al): 0.01 to 0.07%, Ti: 0.09% or less, and a balance of iron (Fe) and unavoidable impurities.
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- Other References: NPL: on-line translation of JP 2011137210 A, Jul. 2011 (Year: 2011). cited by examiner ; Chinese Office Action—Chinese Application No. 201880094086.5 dated Jun. 24, 2022. cited by applicant ; Japanese Office Action—Japanese Application No. 2020-566277 dated Dec. 22, 2021. cited by applicant ; European Search Report—European Application No. 18920561.0 dated Mar. 31, 2021. cited by applicant ; Interantional Search Report—PCT/KR2018/006244 dated Feb. 22, 2019. cited by applicant
- Primary Examiner: Yang, Jie
- Attorney, Agent or Firm: CANTOR COLBURN LLP
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