Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0226—Hot rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
  • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium

Definitions

• the present invention relates to a thick steel plate.
• the present invention relates to a thick steel plate that is excellent in toughness in a weld heat-affected zone (hereinafter, referred to as "HAZ"), that is used in marine structures such as oil and natural gas drilling facilities at sea.
• HZ weld heat-affected zone
• the heating temperature during welding increases at an area nearer to a fusion line.
• austenite grains coarsen markedly. Consequently, the HAZ micro-structure after cooling coarsens and the HAZ toughness deteriorates.
• the known methods for improving the HAZ toughness include, for example, methods that control the grain diameter in a HAZ.
• the methods that control the grain diameter include a method that inhibits coarsening of austenite grains in the welding heating process by dispersing a large amount of fine pinning particles in the steel, and a method that promotes intragranular transformation in a cooling process of welding by dispersing particles that act as nuclei for ferrite transformation in the steel to thereby break up the interior of the grains.
• Patent Document 1 discloses a steel material in which oxides composed of Mg, Mn and Al and composite inclusions which are composed of MnS and have a grain diameter of less than 0.6 ⁇ m are dispersed and formed in an amount of 1 ⁇ 10 6 per mm 3 in steel materials.
• the steel material inhibits coarsening of prior-austenite grains, and by this means secures excellent toughness even when high heat input welding with input heat of 300 kJ/cm or more is performed.
• Patent Document 2 discloses a thick steel plate in which a large amount of Mn oxides and Al oxides that are liable to act as precipitation nuclei for MnS particles are finely dispersed in the steel.
• the thick steel plate has favorable HAZ toughness even when high heat input welding with input heat of 200 kJ/cm is performed.
• Patent Document 3 discloses a steel plate having a plate thickness of 10 to 35 mm in which the particle size and number density of TiN particles, MnS particles and composite particles having an equivalent circular diameter of 0.5 to 2.0 ⁇ m contained in the steel plate are controlled to within predetermined ranges.
• the growth of austenite grains in the steel plate is inhibited by a pinning effect when the steel plate is heated by welding.
• the micro-structure is refined by ferrite transforming to become nuclei. By this means, the HAZ toughness during high heat input welding of the steel plate increases.
• Patent Document 4 discloses a steel for a welded structure which includes the following composition: by mass%, C at a C content [C] of 0.010 to 0.065%; Si at a Si content [Si] of 0.05 to 0.20%; Mn at a Mn content [Mn] of 1.52 to 2.70%; Ni at a Ni content [Ni] of 0.10% to 1.50%; Ti at a Ti content [Ti] of 0.005 to 0.015%; O at a content [O] of 0.010 to 0.0045%; N at a N content [N] of 0.002 to 0.006%; Mg at a Mg content [Mg] of 0.0003 to 0.003%; Ca at a Ca content [Ca] of 0.0003 to 0.03%; and the balance composed of Fe and unavoidable impurities.
• a steel component parameter P CTOD is 0.065% or less, and a steel component hardness parameter CeqH is 0.235% or less.
• An objective of the present invention is to provide a thick steel plate having excellent HAZ toughness even when high heat input welding is performed.
• the present inventors conducted intensive studies to solve the above described problem, and as a result obtained the findings described hereunder.
• the known conventional techniques include (i) a technique that utilizes a pinning effect which inhibits the growth of a prior-austenite grain boundary by means of TiN or the like, and (ii) a technique that causes fine intragranular ferrite to grow using inclusions that are present within prior-austenite grains as starting points, to thereby refine the grains.
• the present inventors found that by controlling balance between the contents of Ti, Al, O and N during the steelmaking process, fine TiN particles that were caused to be dispersed in the steel inhibit the growth of austenite grains in HAZs by a pinning effect, and thereby inhibit the growth of coarse austenite grains.
• Control of inclusions that act as formation nuclei for intragranular ferrite is effective for effectively causing intragranular ferrite to grow within austenite grains during welding.
• the following matters have been ascertained regarding the growth mechanism of intragranular ferrite.
• the present inventors found that the MnS composite amount of an inclusion that serves as a nucleus of intragranular ferrite influences the growth of the intragranular ferrite.
• the driving force that diffuses Mn increases because a larger Mn concentration gradient is formed around the inclusion.
• an Mn-depleted zone is formed more easily.
• a small amount of MnS is composited, it is difficult for a Mn concentration gradient to be formed around the inclusion. As a result, it is difficult for an Mn-depleted zone to be formed.
• the present inventors found that to obtain a grain refining effect, it is necessary for the inclusions in the steel to satisfy the following requirements.
• the growth of coarse grains is inhibited by TiN particles, the composite form of Ti-based composite oxides is controlled, and the amount and number density of MnS that is composited with inclusions is controlled to thereby effectively precipitate intragranular ferrite.
• the present invention is based on the foregoing findings and is as enumerated hereunder.
• a thick steel plate that has excellent HAZ toughness even in a case where high heat input welding is performed.
• the C has an action that enhances the strength of the base metal and a HAZ.
• the C content is 0.01% or more, and in order to secure the strength of the base metal and a HAZ and to ensure the HAZ low-temperature toughness, the C content is preferably 0.02% or more, more preferably is 0.05% or more, and further preferably is 0.06% or more.
• the C content is more than 0.20%, a HAZ is liable to form a hard micro-structure, and hence the HAZ toughness decreases. Therefore, the C content is 0.20% or less, and in order to ensure the strength of the base metal and the HAZ as well as the HAZ low-temperature toughness, the C content is preferably 0.15% or less and more preferably is 0.08% or less.
• the Si acts as a deoxidizer during production of the steel material, and therefore is effective for controlling the oxygen amount, and also dissolves in the steel and increases the strength. Therefore, the Si content is 0.10% or more, and in order to control the oxygen amount to an appropriate amount and also secure the HAZ low-temperature toughness the Si content is preferably 0.13% or more.
• the Si content is more than 0.25%, the toughness of the base metal decreases and the HAZ is liable to form a hard micro-structure, and hence the HAZ toughness decreases. Therefore, the Si content is 0.25% or less, and in order to control the oxygen amount to an appropriate amount and also secure the HAZ low-temperature toughness the Si content is preferably 0.18% or less.
• Mn acts as an austenite stabilizing element, and inhibits production of coarse ferrite at the grain boundary. Therefore, the Mn content is 1.30% or more, and in order to inhibit production of coarse ferrite and also prevent segregation, the Mn content is preferably 1.40% or more.
• the Mn content is 2.50% or less, and in order to inhibit production of coarse ferrite and also prevent segregation, the Mn content is preferably 2.10% or less, and more preferably is 2.00% or less.
• P is an impurity element. A decrease in the grain boundary strength in a HAZ is inhibited by the P content decreasing. Therefore, the P content is 0.01% or less
• the S content is 0.0010% or more.
• the S content is preferably 0.0020% or more.
• the S content is more than 0.0100%, coarse singular MnS precipitates, and consequently the HAZ toughness decreases. Therefore, the S content is 0.0100% or less, and in order to cause MnS to compositely precipitate and also secure the low-temperature toughness of HAZs, the S content is preferably 0.0050% or less.
• Ti is essential for forming Ti-based oxides.
• the Ti content is 0.005% or more in order to obtain a sufficient inclusion density, and in order to secure a sufficient inclusion density and also ensure the HAZ toughness the Ti content is preferably 0.009% or more.
• the Ti content is more than 0.030%, since carbides such as TiC are easily formed, the HAZ toughness decreases. Therefore, the Ti content is 0.030% or less, and in order to secure a sufficient inclusion density and also ensure the HAZ toughness the Ti content is preferably 0.020% or less.
• Al is an impurity element.
• the formation of Ti-based oxides is inhibited by an increase in the Al content. Therefore, the Al content is 0.003% or less.
• O is essential for formation of Ti-based composite oxides.
• the O content is 0.0010% or more.
• the O content is more than 0.0050%, coarse oxides that can become fracture starting points are easily formed. Therefore, the O content is 0.0050% or less, and the O content is preferably 0.0030% or less in order to inhibit the formation of coarse inclusions.
• N contributes to refining the grains by bonding with Ti to form TiN.
• the N content is more than 0.0100%, the Ti amount that is necessary for TiN precipitation increases, and it is difficult for Ti oxides to be formed and the TiN also agglomerates and becomes the starting point of fractures. Therefore, the N content is 0.0100% or less, and in order to stably secure a Ti amount for forming Ti oxides the N content is preferably 0.0080% or less, and more preferably is 0.0050% or less.
• the Cu may be contained as required in order to increase the strength. However, if the Cu content is more than 0.50%, hot embrittlement occurs and the quality of the slab surface decreases. Therefore, the Cu content is 0.50% or less, and preferably is 0.30% or less.
• the Cu content is preferably 0.01% or more, and more preferably is 0.25% or more.
• Ni may be contained as required in order to increase the strength without lowering the toughness.
• Ni is an austenite stabilizing element, if the Ni content is more than 1.50%, it is difficult for intragranular ferrite to be produced. Therefore, the Ni content is 1.50% or less, and in order to promote production of intragranular ferrite the Ni content is preferably 1.00% or less.
• the Ni content is preferably 0.01% or more, more preferably is 0.50% or more, and further preferably is 0.60% or more.
• the Cr may be contained as required in order to increase the strength. However, if the Cr content is more than 0.50%, the HAZ toughness decreases. Therefore, the Cr content is 0.50% or less, and preferably is 0.30% or less.
• the Cr content is preferably 0.01% or more, and more preferably is 0.10% or more.
• Mo noticeably increases the strength when contained in a small amount, and hence Mo may be contained as required. However, if the Mo content is more than 0.50%, the HAZ toughness markedly decreases. Therefore, the Mo content is 0.50% or less, and preferably is 0.30% or less.
• the Mo content is preferably 0.01% or more.
• V is effective for improving the strength and toughness of the base metal, and hence may be contained as required. However, if the V content is more than 0.10%, V forms carbides such as VC, and the toughness decreases. Therefore, the V content is 0.10% or less, and preferably is 0.05% or less.
• the V content is preferably 0.01% or more, and more preferably is 0.03% or more.
• Nb is effective for improving the strength and toughness of the base metal, and hence may be contained as required. However, if the Nb content is more than 0.05%, carbides such as NbC are easily formed, and the toughness decreases. Therefore, the Nb content is 0.05% or less, and preferably is 0.03% or less.
• the Nb content is preferably 0.01% or more.
• the balance other than the above elements is Fe and impurities.
• impurities refers to components which, during industrial production of the steel, are mixed in from raw material such as ore or scrap or due to various factors in the production process, and which are allowed to be contained in an amount that does not adversely affect the present invention.
• a composite inclusion in which MnS is present around a Ti oxide is contained in the steel.
• the area fraction of the MnS in a cross-section of the composite inclusion is 10% or more and less than 90%.
• the proportion that MnS accounts for in the peripheral length of the composite inclusion is 10% or more, and the number density of the composite inclusions that have a grain diameter in a range of 0.5 to 5.0 ⁇ m is in a range of 10 to 100 per mm 2 .
• the MnS amount in the composite inclusion is defined by measuring the area fraction of MnS in the cross-sectional area of the composite inclusion. If the area fraction of the MnS in the cross-section of the composite inclusion is less than 10%, the MnS amount in the composite inclusion is small and a sufficient Mn-depleted zone cannot be formed. Therefore, it is difficult to produce intragranular ferrite.
• the composite inclusion is mainly composed of MnS, and the proportion that a Ti-based oxide accounts for decreases. Therefore, because the Mn absorbability decreases and a sufficient Mn-depleted zone cannot be formed, production of intragranular ferrite is difficult.
• the MnS in the composite inclusion is formed around a Ti-based oxide. If the proportion that MnS accounts for in the peripheral length of the composite inclusion is less than 10%, an initial Mn-depleted zone that is formed at the boundary surface between MnS and the matrix will be small. Therefore, since the amount of intragranular ferrite that is produced will be insufficient even if welding is performed, favorable low-temperature HAZ toughness will not be obtained. Therefore, the proportion that MnS accounts for in the peripheral length with respect to the matrix of the composite inclusion is 10% or more.
• the proportion of MnS is the larger the initial Mn-depleted zone becomes, and the easier it becomes to produce intragranular ferrite. Therefore, although an upper limit of the proportion of MnS is not defined, normally the proportion of MnS is 80% or less.
• the grain diameter of a composite inclusion is less than 0.5 ⁇ m, the Mn amount that can be absorbed from the area surrounding the composite inclusion will be small, and as a result it will be difficult to form Mn-depleted zones that are necessary in order to produce intragranular ferrite.
• the grain diameter of the composite inclusion is larger than 5.0 ⁇ m, the composite inclusion will become a starting point for a fracture.
• the term "grain diameter” refers to a circle-equivalent diameter.
• the number density of the composite inclusions is 10 per mm 2 or more.
• the number density of the composite inclusions is 100 per mm 2 or less.
• the first term that is indicated by (Ti_TiO/O) represents the balance between the Ti content and the O content that become Ti oxides.
• the first term is calculated by deducting a Ti amount required for TiN formation that is calculated based on the N content in the steel from the total Ti content. The larger the value of the first term is, the easier it is for Ti oxides to form. When the first term is a negative value, Ti oxides are not formed.
• the second term that is indicated by (Mn_MnS) in formula (i) represents the Mn amount that becomes MnS.
• the second term is calculated based on the S content in the steel. The larger the value of the second term is, the easier it is for a large amount of MnS to be composited.
• the symbol R1 represents the average value of the area fraction of MnS in a cross-section of composite inclusions
• the symbol R2 represents the average value of the proportion that MnS accounts for in the peripheral length of the composite inclusions.
• the value X obtained by formula (i) indicates the ease with which Ti oxides that composite with MnS are formed, and also the degree of MnS compositing of the composite inclusions that are formed.
• the steel material exhibits excellent toughness.
• the value X obtained from formula (i) is less than 0.04, the Ti amount required to form Ti oxides, the S amount and Mn amount required for formation of MnS, or the proportion that MnS accounts for is insufficient. In other words, the state is one in which inclusions that are effective for intragranular transformation are not formed. Therefore, in order to form effective Ti oxides, the value X is 0.04 or more, and preferably is 0.50 or more, and more preferably is 1.00 or more.
• the value X obtained from formula (i) is more than 9.70, agglomeration is liable to occur due to an excess of Ti oxides being formed. As a result, inclusions become starting points for fractures due to coarse inclusions being formed. In addition, since inclusions that are almost singular MnS inclusions are liable to be formed, intragranular transformation is no longer promoted. Consequently, coarse micro-structure increases, and CTOD properties deteriorate. Therefore, the value X is 9.70 or less, more preferably is 5.00 or less, and further preferably is 4.00 or less.
• the thick steel plate according to the present invention has composite inclusions as described above, and the plate thickness is 50 mm or more, the HAZ low-temperature toughness is excellent.
• the thick steel plate according to the present invention has excellent HAZ low-temperature toughness.
• the plate thickness of the thick steel plate is 100 mm or less.
• the yield stress of the thick steel plate according to the present invention is 400 to 500 MPa.
• a method for producing the thick steel plate according to the present invention is not particularly limited.
• the thick steel plate can be produced by heating a slab having the chemical composition described above, and thereafter subjecting the slab to hot rolling, and finally performing cooling.
• the ausform rolling reduction that is, the rolling reduction at 950°C or less before accelerated cooling is preferably 20% or more. If the rolling reduction at 950°C or less before accelerated cooling is less than 20%, depending on the rolling the majority of dislocations introduced immediately after rolling may disappear due to recrystallization, and therefore not function as nuclei for transformation. As a result, the micro-structure after transformation coarsens, and in many cases embrittlement caused by dissolved nitrogen is a problem. Therefore, the rolling reduction at 950°C or less before accelerated cooling is preferably 20% or more.
• the flow rate of the Ar gas was regulated within the range of 100 to 200 L/min, and the blowing time period was regulated within the range of 5 to 15 min.
• the respective elements were added in an RH vacuum degassing apparatus for component adjustment, and a 300 mm slab was cast by continuous casting.
• the slab was heated within a range of 1000 to 1100°C in a heating furnace.
• hot rolling at 760°C or higher was performed until becoming a thickness of 2t (t: final finishing plate thickness), and thereafter the slab was subjected to hot rolling in a temperature range of 730 to 750°C until becoming the final finishing plate thickness t.
• the water cooling was performed at -2 to -3°C/sec until the temperature became 200°C or less, and a specimen was prepared.
• the test specimen used for composite inclusion analysis was taken from a portion that, when the plate thickness of the specimen is taken as "t", was at a plate thickness of 1/4t.
• the MnS area fraction and the proportion that MnS accounted for in the peripheral length of the composite inclusions were measured from a mapping image obtained by performing area analysis of composite inclusions using an electron probe microanalyzer (EPMA).
• EPMA electron probe microanalyzer
• the MnS area fraction was calculated by measuring the cross-sectional area of the entire composite inclusion and the cross-sectional area that an MnS portion accounted for in the entire composite inclusion from an image.
• the proportion that an MnS portion accounted for in the peripheral length of the composite inclusion was calculated by measuring the peripheral length of the Ti oxide in the composite inclusion and the length of an MnS boundary surface that contacted the Ti oxide from an image.
• the MnS area fraction and the proportion that MnS accounted for in the peripheral length of the composite inclusions was determined by performing analysis by EPMA for twenty composite inclusions per specimen, and calculating the average values. The results are shown in Table 1.
• the number density of the composite inclusions was calculated by calculating the number of composite inclusions whose grain diameter was in the range of 0.5 to 5.0 ⁇ m by means of an automatic inclusion analyzer combined with SEM-EDX, and from shape measurement data of the detected composite inclusions. The results are shown in Table 1.
• a JIS No. 4 tensile test specimens was taken from a 1/4 t position when taking the plate thickness of the prepared specimen as "t", and a tension test was performed at room temperature, and the yield stress (YP) and tensile strength (TS) of the rolled base metal were measured.
• ⁇ Among the three test specimens, 0 to 2 of the test specimens were over the gauge, and all of the test specimens that were not over the gauge had a CTOD value of 0.4 mm or more ⁇ : Among the three test specimens, the CTOD value of at least one test specimens was less than 0.4 mm Note that, the term "over the gauge” means that an attached grip gauge could be fully opened to the limit. Further, since the CTOD property of a joint at a typically required temperature of -20°C is a CTOD value of 0.4 mm or more, the standard for the CTOD value was made 0.4 mm.
• Example 1 430 620 >1.4 >1.4 >1.4 ⁇
• Example 2 438 631 >1.4 >1.4 >1.4 ⁇
• Example 3 442 635 >1.4 >1.4 >1.4 ⁇
• Example 4 422 611 >1.4 >1.4 >1.4 ⁇
• Example 5 436 624 >1.4 >1.4 >1.4 ⁇
• Example 6 434 639 >1.4 >1.4 >1.4 ⁇
• Example 7 440 645 >1.4 >1.4 >1.4 ⁇
• Example 8 426 614 >1.4 >1.4 >1.4 ⁇
• Example 9 421 605 >1.4 >1.4 ⁇
• Example 10 421 607 >1.4 >1.4 ⁇
• Example 11 420 603 >1.4 >1.4 >1.4 ⁇
• Example 12 431 621 >1.4 >1.4 >1.4 ⁇
• Example 13 440 635 >1.4 >1.4 1.256 ⁇
• Example 14 438 629 >1.4 >1.4 1.113 ⁇
• Example 15 461 670 >1.4 0.681 1.052 ⁇
• Example 16 463 671 >1.4 0.6
• test specimens of examples 1 to 27 satisfied all conditions with respect to the ranges of the present invention, and hence the result of the CTOD test for these examples was "pass".
• Example 3 steels having the chemical compositions of test number examples 31 to 61 and comparative examples 21 to 32 shown in Table 3 were melted by an actual production process, and specimens were prepared. Further, in a similar manner to Example 1, calculation of the MnS area fraction at a cross-section of composite inclusions as well as the proportion that MnS accounted for in the peripheral length of the composite inclusions, and calculation of the number density of the composite inclusions was performed. The results are shown in Table 3.
• Example 4 Further, a tension test and a CTOD test were performed similarly to Example 1. The test results are shown in Table 4.
• a thick steel plate can be provided that is excellent in low-temperature toughness for a HAZ when high heat input welding is performed. Therefore, the thick steel plate of the present invention can be favorably used for welded structures such as marine structures, and particularly for thick steel plates that have a plate thickness of 50 mm or more.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Heat Treatment Of Steel (AREA)
• Treatment Of Steel In Its Molten State (AREA)

Applications Claiming Priority (3)

Publications (3)

Family

ID=60116163

Family Applications (1)

Country Status (4)

Families Citing this family (3)

Family Cites Families (10)

• 2017
  • 2017-04-21 EP EP17786057.4A patent/EP3447162B1/en active Active
  • 2017-04-21 WO PCT/JP2017/016090 patent/WO2017183720A1/ja active Application Filing
  • 2017-04-21 CN CN201780024463.3A patent/CN109072383B/zh active Active
  • 2017-04-21 KR KR1020187033428A patent/KR20180132909A/ko not_active Application Discontinuation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events