High-strength steel sheet and method for producing same
A high-strength steel plate and a technology for a manufacturing method, which are applied in the field of high-strength thick steel plates and their manufacturing, can solve the problems of low productivity, decreased crack sensitivity of segregation parts, etc.
Inactive Publication Date: 2013-07-03
NIPPON STEEL CORP
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- Abstract
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- Claims
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Problems solved by technology
Since the amount of Mn must be 1.8% or more, the crack susceptibility of the segregation part may decrease, and since low-temperature rolling in the ferrite-austenite two-phase region is necessary, the productivity is low
Method used
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[0096] Using the production conditions shown in Table 3 and Table 4, steel sheets No. A to AP with a plate thickness of 6 to 25 mm are manufactured from steel sheets obtained by melting steels having steel compositions No. A to AP having the composition shown in Table 1 and Table 2. .1~55. In Table 1 and Table 2, when Cu, Ni, V, and Ca were not intentionally added to the steel, the amounts of these chemical components were put in parentheses. In addition, in Table 3 and Table 4, after stopping the accelerated cooling (water cooling), each steel plate was left to cool without winding the steel plate until the temperature of the steel plate reached 250°C.
[0097] For these steel sheets Nos. 1 to 55, the microstructure fractions of lower bainite and martensite, the number of cementite (number density) of 50 nm or more, and prior austenite were measured by the methods shown below. The aspect ratio, the diffusible hydrogen content of the weld metal in the y-type weld crack test, ...
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Abstract
This high-strength steel sheet has a chemical composition containing, by mass%, at least 0.05% and less than 0.10% of C, from 0.20% to 0.50% inclusive of Si, at least 0.20% and less than 1.20% of Mn, from 0.20% to 1.20% inclusive of Cr, from 0.20% to 0.60% inclusive of Mo, from 0.010% to 0.050% inclusive of Nb, from 0.005% to 0.030% inclusive of Ti, from 0.01% to 0.10% inclusive of Al, from 0.0003% to 0.0030% inclusive of B, from 0% to 0.10% inclusive of V, from 0% to 0.50% inclusive of Cu, and from 0% to 0.0030% inclusive of Ca, Ni is limited to no more than 0.1%, P to no more than 0.012%, S to no more than 0.005%, and N to no more than 0.0080%, and the remainder comprises Fe and unavoidable impurities. Pcm is no greater than 0.22%, A is no greater than 2.0, the sum of the compositional fraction of lower bainite and the compositional fraction of martensite is at least 90%, the compositional fraction of the lower bainite is at least 70%, the aspect ratio of prior-austenite grains is at least 2, the yield strength is at least 885 MPa, and the tensile strength is from 950 MPa to 1130 MPa inclusive.
Description
technical field [0001] The present invention relates to a high-strength thick steel plate excellent in weldability and a method for producing the same. In particular, the present invention relates to structural parts used for construction machinery and industrial machinery, and have a yield strength of 885 MPa or more, a tensile strength of 950 MPa or more and 1130 MPa or less, and are mostly high-strength thick steel plates with a plate thickness of 6 mm or more and 25 mm or less. Production method. [0002] This application claims priority based on Japanese Patent Application No. 2010-248032 for which it applied in Japan on November 5, 2010, and uses the content here. Background technique [0003] With the increase in the height of buildings in recent years, construction machinery such as cranes and concrete pump trucks tend to increase in size. In order to suppress the increase in the weight of construction machinery due to the increase in the size of construction machi...
Claims
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Login to View More IPC IPC(8): C22C38/54C21D8/02
CPCC22C38/02C22C38/04C22C38/06C22C38/22C22C38/26C22C38/28C22C38/32C22C38/42C22C38/44C22C38/46C22C38/48C22C38/50C22C38/54C21D8/02
Inventor 熊谷达也后藤道典川端纪正
Owner NIPPON STEEL CORP