US20070122650A1 - Steel for exhaust gas processing equipment and exhaust gas duct excellent in wear resistance or wear resistance and gas cutting property - Google Patents

Steel for exhaust gas processing equipment and exhaust gas duct excellent in wear resistance or wear resistance and gas cutting property Download PDF

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US20070122650A1
US20070122650A1 US10/579,172 US57917204A US2007122650A1 US 20070122650 A1 US20070122650 A1 US 20070122650A1 US 57917204 A US57917204 A US 57917204A US 2007122650 A1 US2007122650 A1 US 2007122650A1
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exhaust gas
steel
wear resistance
duct
processing equipment
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Akira Usami
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Nippon Steel Corp
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Nippon Steel Corp
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Priority claimed from JP2004324855A external-priority patent/JP4571848B2/ja
Priority claimed from JP2004324848A external-priority patent/JP4571847B2/ja
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Assigned to NIPPON STEEL CORPORATION reassignment NIPPON STEEL CORPORATION ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: USAMI, AKIRA
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    • 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
    • C22C38/04—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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/42—Ferrous alloys, e.g. steel alloys containing chromium with nickel with 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
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12861—Group VIII or IB metal-base component
    • Y10T428/12951—Fe-base component
    • Y10T428/12958—Next to Fe-base component
    • Y10T428/12965—Both containing 0.01-1.7% carbon [i.e., steel]

Definitions

  • the present invention relates to a steel for exhaust gas processing equipment and to an exhaust gas duct exhibiting a excellent durability and excellent in constructability, repairability, and economy in an exhaust gas environment of a converter and an electric melting furnace in refining of a ferrous metal or other metal.
  • exhaust gas out of a metal refining furnace contains corrosive gas ingredients or metal dust
  • the passage of the exhaust gas in exhaust gas equipment undergoes severe wear.
  • the exhaust gas reaches a temperature of 1200° C.
  • combustible gas is burnt in the combustion tower before being passed through the exhaust gas equipment.
  • an exhaust gas duct formed into a double-wall tube structure made of welded carbon steel sheets. Exhaust gas runs through the inside tube, and cooling water runs between the inside tube and the outside tube.
  • steel tubes are arranged at the inside surface of a duct to create a water cooling tube panel, and cooling water runs through their insides. These will be called “hereinafter collectively exhaust gas water cooling ducts”.
  • the maximum wear rate of perforated parts has reached several mm to 20 mm/year in conventional steel.
  • the wear is believed to be caused by abrasion due to collision by solid grains, molten salt corrosion due to dust, wet corrosion accompanying the formation of concentrated electrolytes due to absorption of moisture etc., but the-most dominant process of wear among these factors has not been determined much at all.
  • Techniques for modifying the surface contacting the exhaust gas include, for example, 1) lining the inside with heat resistant, refractory, 2) lining the inside with an inorganic caster, 3) forming a thick melt sprayed layer, 4) employing clad steel having a high alloy steel as its surface layer, some of whom have already been proposed.
  • Examples include melt spray buildup with a stainless steel-based alloy as disclosed in Japanese Patent Publication (B) No. 4-80089, forming a melt sprayed coating layer of an alloy of ingredients forming an oxide at 800° C. as disclosed in Japanese Patent No. 2565727, and coating by a self melting melt sprayed alloy such as a Ni—Cr—Mo—B system as disclosed in Japanese Patent Publication (A) No. 2003-231909 (metal coating forming alloy layer by a base material and melt sprayed metal).
  • an exhaust gas duct using one side of the carbon steel as the surface contacting the exhaust gas (gas contact surface) and the remaining side as the coolant surface is extremely excellent in material costs, constructability, repairability, and economy. Therefore, an exhaust gas duct equivalent to a carbon steel exhaust gas duct in constructability and repairability, remarkably excellent in durability of the gas contact surface, and economically feasible as well has been strongly sought.
  • the present invention was made to overcome the above problems and has as its object to provide a steel for exhaust gas processing equipment excellent in durability, workability, and constructability in an exhaust gas environment of a converter and electric furnace, as melting or refining equipment for steel and metal or ash melting furnace, and an exhaust gas duct made of such steel.
  • the present invention was made based on the above discovery and has as its gist the following:
  • a steel for exhaust gas processing equipment excellent in wear resistance and gas cutting property as set forth in (4) further containing, by mass %, one or more of
  • An exhaust gas duct wherein a gas contact surface of a passage of exhaust gas in the exhaust gas duct is comprised of steel containing, by mass %,
  • An exhaust gas duct wherein a gas contact surface of a passage of exhaust gas in the exhaust gas duct is comprised of a double-layer steel having as a surface layer of said steel containing, by mass %,
  • An exhaust gas duct wherein a gas contact surface of a passage of exhaust gas in the exhaust gas duct is comprised of a steel containing, by mass %,
  • the steel of the present invention exhibits excellent durability in an environment of exhaust gas processing equipment of a metal melting or metal refining furnace and has workability and constructability equivalent to a carbon steel.
  • the exhaust gas duct of the present invention exhibits an excellent durability in an exhaust gas environment of a metal melting or metal refining furnace or ash melting furnace and has an constructability, repairability, and economy equivalent to a carbon steel.
  • FIG. 1 is a view showing the effect of the amount of Cr on the maximum and average wear rates of steel to which Cr alone is added in an inside tube of a water-cooled duct of a steel melting electrical furnace.
  • FIG. 2 is a view showing the effect of composite addition of Cu, Ni, and Sb on the wear rate of 5% Cr steel in an inside tube environment of a water-cooled exhaust gas duct.
  • FIG. 3 is a view showing an example of the structure of a double-wall water-cooled duct.
  • FIG. 4 is a view showing an example of an inside tube of a double-wall water-cooled duct.
  • FIG. 5 is a view showing an example of the structure of a duct comprised of water-cooled panels, wherein (a) shows a cross-section of the duct and (b) shows a cross-section of a water cooling tube enlarged.
  • the % means the mass %.
  • the framework of the steel of the present invention is that the composite addition of low C—Cr—Cu—Ni— (Mo, W, Mo+W)—Sb or low C—Cr-low Si—Cu—(Mo, W, Mo+W)—Sb, enables (1) excellent durability in exhaust gas processing equipment environment of a metal refining furnace and (2) simultaneous provision of a workability and constructability equivalent to ordinary steel by using together with an austenitic welding material.
  • the framework of the present invention comprises; first that the exhaust gas duct structure has a forced cooling mechanism wherein a low C—Cr—Cu—Ni—(Mo, W, Mo+W)—Sb steel contacts the gas and the other side is water-cooled in a passage of exhaust gas passage and a passage of a cooling medium; and second that the exhaust gas duct is fabricated by welding steel-sheets having the above composition using an austenitic welding material or ferritic welding material of the same composition as the steel.
  • the gas contact surface of exhaust gas processing equipment degrades (declines in thickness) due to the wear caused by interaction of the exhaust gas and the material.
  • wear a chemical corrosion or a physical abrasion etc. compositely act.
  • any phenomenon inviting a reduction in thickness of the surface of the material contacting the gas in exhaust gas processing equipment is called “wear”.
  • the steel is evaluated for wear resistance using the average wear rate and the maximum wear rate as indicators.
  • FIG. 1 shows the results of using the composition of the comparative example A3 shown in Table 1 (or Table 4) as the basic composition and changing the amount of Cr so as to investigate the effects of Cr on the average wear rate and maximum wear rate at the inside surface of an exhaust gas duct of a electric furnace for steel making. From FIG. 1 , it is learned that to obtain a sufficient effect by the average wear rate, 4.0% or more of Cr has to be added.
  • FIG. 2 shows the result of investigation of the effects in the case of compositely adding Cu, Ni, Mo, and Sb to 5% Cr in a wear environment of a steel exhaust gas duct. If compositely adding Cu—Ni—Mo—Sb in a Cr-containing steel, it is learned that the maximum wear rate is reduced to 2 mm/y (year) or less and that the wear resistance is remarkably improved. That is, if even not one element of the Cu, Ni, Mo, and Sb is included, an excellent wear resistance is not obtained.
  • excellent wear resistance specifically means, based on the fact that the comparative example shown in FIG. 2 has a maximum wear rate over 5 mm/y (year), a maximum wear rate of 5 mm/y (year) or less, preferably 3.5 mm/y (year) or less.
  • the inventors discovered that in order to secure a sufficient gas cutting property by acetylene gas in steel containing Cr—Cu—Ni—Mo—Sb, that is, a certain level of cutting speed, simultaneously with suppressing the blow holes, adding the deoxidation elements of Si and Al and reducing the N in the steel to the maximum extent alone are not sufficient and that there is an optimal balance of Si and Al. That is, the inventors discovered that a good cut surface can be obtained in the range of Si: 0.01 to 0.5% and Al: 0.005 to 0.5%.
  • C is preferably as small an amount as possible from the viewpoint of the wear resistance of the exhaust gas duct environment, but to secure the strength, addition of 0.001% or more is necessary, so the lower limit was made 0.001%. If over 0.2%, the wear resistance, cold workability, and weldability are impaired, so 0.001 to 0.2% was made the range of limitation.
  • Cu has to be added to suppress local wear together with Ni, (Mo, W, or Mo+W), and Sb of 0.1% or more. If added over 1%, an excessive rise in strength and a drop in the manufacturability and cold workability are induced, so 0.1 to 1% is made the range of limitation. Preferably, addition of 0.2 to 0.5% gives an excellent balance of cold workability and wear resistance.
  • Ni is added to suppress the local wear together with Cu, (Mo, W, or Mo+W), and Sb of 0.01% or more, but the effect is sufficient at 1%, so 0.01 to 1% is made the range of limitation. However, in the case of a steel for an exhaust gas duct, the effect of suppression of local wear is sufficient at 0.5%, so 0.01 to 0.5% is made the range. of limitation.
  • Cr is added to secure wear resistance in an amount of 4.0% or more. Even if added over 9.0%, the wear resistance is saturated, so 4.0 to 9.0% was made the range of limitation. Due to the effect of composite addition of 4.0 to 9.0% Cr—Cu—Ni—Sb—(Mo, W, or Mo+W), the wear resistance is remarkably improved compared with a system of sole addition of 4.0 to 9.0% of Cr.
  • the range of limitation is preferably made 4.0 to 6.0%. If considering the workability, gas cutting property, and wear resistance, 4.5 to 5.5% is more preferable.
  • Sb is added for the purpose of suppressing the local wear together with the Cu, Ni, or (Mo, W, or Mo+W) of 0.01% or more, but even if added over 0.2%, the effect is saturated, so 0.01 to 0.2% was made the range of limitation. From the viewpoint of the hot workability, 0.05 to 0.15% is preferable.
  • Mo and W are added for the purpose of suppressing the local wear, alone or together, together with Cu, Ni, and Sb of 0.005% or more, but if added over 0.5%, conversely the weldability or wear resistance is inhibited, so 0.005 to 0.5% was made the range of limitation. From the viewpoint of the wear resistance, economy, and weldability, 0.01 to 0.1% is preferable.
  • Si if added for deoxidation in an amount of 0.01% or more, reduces the gas ingredients and reduces the blow holes, so is an essential element for securing gas cutting property, but if over 0.5%, the heat affected zone (HAZ) deteriorates in toughness, so 0.01 to 0.5% was made the range of limitation. To achieve both wear-resistance and good gas cutting property, addition of 0.01 to 0.3% is preferable. When considering the steel manufacturability, weldability, etc., 0.1 to 0.3% is more preferable.
  • Mn is added for securing the steel strength and for deoxidation in an amount of 0.1% or more, but excessive addition causes excessive strength and impairs the cold workability, so 0.1 to 2% was made the range of limitation.
  • P is an impurity element. If over 0.05%, the weldability and wear resistance fall, so 0.05% or less was made the range of limitation. Note that the smaller the amount of P, the better, so 0.02% or less is preferable. Note that the lower limit value includes 0%.
  • S is an impurity element. If over 0.02%, the lamellar tear resistance falls, so the amount was limited to 0.02% or less. On the other hand, if S becomes less than 0.005%, the wear resistance falls, so the amount was limited to 0,005 to 0.02%. If considering the balance of the wear resistance and toughness, 0.005 to 0.015% is preferable.
  • Al is added as a deoxidation element in an amount of 0.005% or more. Along with the increase of Al, the wear resistance is improved, but excessive addition impairs the gas cutting property, so 0.005 to 0.5% was made the range of limitation. To secure a sufficient good gas cutting property, 0.005 to less than 0.03% is preferable.
  • N is over 0.008%, it not only increases the number of blow holes formed at the time of gas cutting and lowers the gas cutting property, but also reduces the toughness, so the upper limit was made 0.008%.
  • the steel of the present invention can exhibit an excellent wear resistance or an excellent wear resistance and gas cutting property, but by selectively adding the following elements, a greater effect can be expected.
  • Ti is added in accordance with need in an amount of 0.002% or more. It has the effect of forming TiO or TiN in the steel and making the grain size of the heat affected zone during welding finer and forming ferrite in the grains so as to improve the toughness or the effect of improving the gas cutting property of Cr—Cu—Ni—(Mo, W, or Mo+W)—Sb steel. In this case, if adding it over 0.2%, the toughness deteriorates, so the range is preferably made 0.002 to 0.2%.
  • Nb, V, Ta, Zr, and B are elements effective for increasing the strength of the steel and are mainly included to adjust the strength in accordance with need. To express these effects, Nb is preferably contained in an amount of 0.002% or more, V in 0.005% or more, Ta in 0.005% or more, Zr in 0.005% or more, and B in 0.0002% or more.
  • Nb is added over 0.2%, V over 0.5%, Ta over 0.5%, Zr over 0.5%, and B over 0.005%, the toughness easily remarkably degrades. Therefore, in accordance with need, when including Nb, V, Ti, Ta, Zr, or B, Nb is preferably included in an amount of 0.002 to 0.2%, V in 0.005 to 0.5%, Ti in 0.002 to 0.2%, Ta in 0.005 to 0.5%, Zr in 0.005 to 0.5%, and B in 0.0002 to 0.005%.
  • Mg, Ca, Y, La, and Ce are effective for control of the morphology of the inclusions and are effective for improvement of the ductility characteristics and further are effective for improvement of the HAZ toughness of the weld joint. Further, the effects of improving the local wear resistance are weak, so these are preferably included in accordance with need.
  • Mg preferably has a lower limit of 0.0001%, Ca of 0.0005%, Y of 0.0001%, La of 0.005%, and Ce of 0.005%.
  • the upper limit are determined by when the inclusions become coarser and by whether the mechanical properties, in particular the ductility and toughness, are adversely affected.
  • Mg and Ca have upper limit of 0.01% and Y, La, and Ce of 0.1%.
  • Sn and Pb are elements effective for further improving the wear resistance and are added in accordance with need, but the effects are preferably exhibited when Sn is 0.01 to 0.3% and Pb is 0.01 to 0.3%.
  • the upper limit is preferably made 0.0040%.
  • Cr differs in the upper limit of the range of limitation when using an austenitic welding material and when using a welding material of a similar composition.
  • Si, Mn, P, and S are essential ingredients when using a welding material of a similar composition. This differs from the case of use of an austenitic welding material. However, the ranges of limitation and reasons for limitation of Si, Mn, P and S are basically the same as the case of the above austenitic welding material.
  • the steel of the present invention is prepared in a converter, electric furnace, or other melting furnace, secondarily refined in accordance with need in a degasification system, ladle, etc. to obtain the predetermined compositions, then the molten steel is continuously cast or cast into steel ingots, then bloomed into a steel slab.
  • this steel slab is hot-rolled, with or without additional heating, to a hot-rolled thin steel sheet or thick steel plate and further is cold-rolled to a cold-rolled thin steel sheet or other steel sheet.
  • it may be hot-rolled for use as sections, steel bars, wire rods, or steel tubes, or other corrosion resistant steel members in various manners.
  • an exhaust gas duct of exhaust gas processing equipment is comprised of a welded structure of a steel, so the steel is required to have the required properties and also welding constructability. Therefore, in order to prevent selective wear of the welding metal and secure a welding constructability equivalent to carbon steel in the present invention, the alloy composition of the welding metal is important.
  • an austenitic welding materials with more Cr, Ni, Cu, Mo, etc. effective for the wear resistance or ferritic welding materials of a low C—Cr—Cu—Ni—(Mo, W, Mo+W)—Sb system the same as the base metal are preferable.
  • the austenitic welding material known art may be used.
  • an austenitic stainless steel for example, SUS309L is commonly used.
  • the surface layer be a wear resistant layer made of steel having the chemical composition of the present invention. From the viewpoint of the durability, a wear resistant layer of 3 mm or more is preferable. It is more preferable that rather than a double-layer steel, the entire material be a steel having a chemical composition limited by the present invention.
  • a water-cooled double-wall structure or an exhaust gas duct comprised of a water-cooled steel tube panel is preferable. This is-because in the case of a water-cooled double-wall structure, even if the exhaust gas is a high temperature of over 300° C., the metal surface temperature of the duct becomes at most several tens of 10° C. and wear due to severe molten salt corrosion (in general, occurring when the metal surface temperature is 300° C. or more) can be avoided.
  • FIG. 3 An example of the structure of an exhaust gas duct of a water-cooled double-wall structure is shown in FIG. 3 .
  • This is a double-wall structure exhaust gas duct comprised of an inside tube 2 made of a clad steel having a surface layer of the gas contact surface having the specific composition of the present invention or a steel having the specific composition of the present invention as a base metal and a weld zone made of an austenitic welding material (for example, SUS309L) and an outside tube 1 made of carbon steel.
  • 3 indicates the passage of the cooling water
  • 4 indicates the passage of the exhaust gas.
  • FIG. 4 An example of the structure of the inside tube comprised of clad steel having steel having the specific composition of the present invention covered on a base material 6 as a wear resistant layer 5 and a weld zone 7 made of an austenitic welding material is shown in FIG. 4 . Note that in FIG. 4, 8 indicates the surface contacting the exhaust gas.
  • the coolant preferably has a temperature of 100° C. or less.
  • water is preferable.
  • the inside tube preferably has a thickness of 6 mm or more from the viewpoint of the durability, more preferably 9 to 16 mm.
  • the method of fabrication of the inside tube may be any method such as sheet rolling, use of a steel tube, spiral working, welding, etc.
  • the surface layer of the gas contact surface may be covered by a heat resistant, abrasion resistant material of the range of limitation of the present invention.
  • FIG. 5 A structural example of an exhaust gas duct comprised of the water-cooled steel tube panel is shown in FIG. 5 .
  • a plurality of water cooling tubes 9 are usually arranged in parallel and welded to the panel.
  • steel sheet having a composition limited by the present invention was welded as a gas contact surface sheet by austenitic welding material.
  • the surface layer of the gas contact surface may also be covered by a heat resistant abrasion resistant material.
  • a sample of a repair use test steel sheet (250 mm ⁇ 250 mm ⁇ 12 mm) was prepared.
  • the test steel sheet was cold bent to the diameter of the inside tube.
  • An inside tube of an exhaust gas duct of an electric furnace for steel making for steel bar was cut open to create a space in advance, then the test steel sheet was welded therein.
  • the welding was performed by arc-welding with a heat input of about 20 kJ/cm and a welding material of an austenitic stainless steel (SUS309L) covered arc-welding rod.
  • SUS309L austenitic stainless steel
  • test samples were cut at a constant cutting speed by straight cutting (sheet thickness 16 mm) and V-groove cutting (16 mm thickness, 30°, 40°). Then the cutting workability and state of the cut surfaces for the case of using acetylene gas or the case of using powder cutting were evaluated, relative to the comparative steel A1, as VG (very good): good, G (good): cutting easy, F (fair): cutting difficult (cut surface requires touchup), and P (poor): cutting impossible.
  • Table 2 shows the results of the above duct explosion test.
  • Table 3 shows the results of the gas cutting property test.
  • the comparative steel A1 is the commercially available common steel for weld structure (JIS G3141 SS400), while A2 is a low alloy steel, but both have low wear resistances. Further, A3 is a low carbon steel to which 4.9% of Cr is solely added. It has an average wear rate better than A1 and A2, but has a maximum wear rate equal to A2 etc., i.e., the effect of addition of Cr is not significant.
  • A4, A5, A6, and A7 contain Cr in an amount of 5.1% and have Si, Cu, Ni, Mo, and Sb compositely added, but A4 is insufficient in Cu, A5 in Ni, A6 in Mo, and A7 in Sb, so the maximum wear rate is not sufficiently suppressed.
  • A8 has a Cr content of a low 3.5%, so the average and maximum wear rates are not sufficiently suppressed by composite addition.
  • A9 contains Si, Cu, Ni, Mo, and Sb in the range of the steel composition prescribed in the present invention, but contains Cr in an amount of 6.9%, so has a gas cutting property inferior to that of the present invention steels.
  • A10 contains Cr in an amount of 4.9% and contains Cu, Ni, Mo, and Sb in amounts in the range of steel composition prescribed in the present invention, but contains 0.65% of Si, so has a gas cutting property inferior to that of the present invention steels.
  • steels B1 to B31 are in the range of steel composition prescribed by the present invention, are excellent in wear resistance, and have a gas cutting property as good as ordinary steel (A1).
  • the steel sheet (1000 mm ⁇ 500 mm ⁇ 12 mm) of each alloy composition shown in Table 4 was cut into two in the longitudinal direction. The two pieces were butt-welded, then the assembly was cold bend to the diameter of an inside tube.
  • the inside tube of an exhaust gas duct of an electric melting furnace for steel bars (site 1) and a water-cooled duct of a converter OG exhaust gas processing equipment (site 2) were cut open to form windows, where the test steel sheets were welded.
  • the welding was performed by arc-welding with a heat input of about 20 kJ/cm and a welding material of an austenitic stainless steel (SUS309L) covered arc-welding rod.
  • SUS309L austenitic stainless steel
  • Table 5 shows the results of the above duct exposure test.
  • A7 Ni 0.03 0.2 0.4 0.01 0.100 5.1 0.20
  • the comparative example A1 is a commercially available common steel for welded structure (JIS G3141, SS400), while A.2 is a low alloy steel. Both have low wear resistances. Further, A3 is a low carbon steel in which 4.9% Cr is solely added. The average wear rate is better than Al and A2, but the maximum wear rate is equal to A2, so the effect of addition of Cr is not significant.
  • A4, A5, A6, and A7 contain Cr in an amount of 5.1% and further have Si, Cu, Ni, Mo, and Sb compositely added, but A4 is insufficient in Cu, A5 in Ni, A6 in Mo, and A7 in Sb, so that maximum wear rate is not sufficiently suppressed.
  • AB has a Cr content of a low 3.0%, so the average and maximum wear rates are not sufficiently suppressed by the composite addition.
  • the steel sheet (300 mm ⁇ 300 mm ⁇ 12 mm) of each alloy composition shown in Table 6 was butt-welded by a weld ferritic alloy welding rod and investigated for welding constructability and weld crack susceptibility.
  • the welding rod was arranged to the alloy composition shown in Table 7 so that the composition in the welding metal of the Cr—Cu—Ni—Mo—Sb important for securing the wear resistance becomes the same extent as the chemical composition of the steel sheet.
  • the welding was performed by arc-welding with an input beat of about 20 kJ/cm.
  • the weld joint C2 obtained by butt-welding of the comparative example steel sheet C2 as a base metal with a welding rod of a composition of the welding metal WM2 (hereinafter referred to as the weld joint C2), low temperature cracking was observed in the welding metal.
  • weld joints having the steel sheets C1, C3, and C4 as base metals and having WM1, WM3, and WM4 as welding metals (hereinafter referred to as the weld joints C1, C3, and C4), the welding constructability and crack susceptibility were good.
  • each of the joints other than the weld joint C2, that is, the weld joints C1, C3, and C4, in same way as Example 1, was attached to the gas contact surface of an exhaust gas double-wall water-cooled duct of a steel refining electric furnace.
  • the section of the duct where the test steel sheet was attached was cut out by gas cutting, then test pieces were cut out, acid washed, then measured for sheet thickness to find the average wear rate and local maximum wear rate, and the wear resistance was evaluated.
  • Table 8 shows the results of the above duct exposure test. TABLE 8 Base metal Welding metal Welding Base Average Max. Average Max. metal metal rate rate rate rate Evaluation Comp. WM1 C1 4.3 7.9 4.8 9.3 Poor wear ex. resistance WM2 C2 — — — — — Weld cracks, no data Inv. WM3 C3 3.9 4.9 3.9 4.9 Excellent ex. WM4 C4 0.4 1.1 0.4 1.1 Excellent
  • the comparative example weld joint C1 has less Cr in both the base metal and welding metal than-the lower limit of Cr prescribed in (3), so it is learned that the wear resistance is inferior to that of the invention examples C3 and C4. Further, as explained above, the comparative example weld joint C2 has Cr in both the base metal and welding metal over the upper limit of Cr prescribed in the aspect of the invention of (3), so it is learned that sufficient weldability cannot be obtained.
  • the steel of the present invention and the exhaust gas duct comprised using the steel when used for example for a duct, heat exchanger, electric dust collector, cooling tower, smokestack, etc. in an exhaust gas processing system of a steel making electric furnace or steel making converter, exhaust gas processing system of an ash melting furnace, or exhaust gas processing system of an incineration equipment of garbage, sludge, etc., extends the lifetime of the equipment due to its excellent durability, enables continuation of the same maintenance and management and same repair methods as with conventional carbon steel, and therefore is extremely high in industrial value.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
  • Heat Treatment Of Articles (AREA)
US10/579,172 2003-11-14 2004-11-12 Steel for exhaust gas processing equipment and exhaust gas duct excellent in wear resistance or wear resistance and gas cutting property Abandoned US20070122650A1 (en)

Applications Claiming Priority (9)

Application Number Priority Date Filing Date Title
JP2003-385593 2003-11-14
JP2003385534 2003-11-14
JP2003-385534 2003-11-14
JP2003385593 2003-11-14
JP2004-324848 2004-11-09
JP2004324855A JP4571848B2 (ja) 2003-11-14 2004-11-09 耐損耗性およびガス切断性に優れた金属製錬炉排煙処理設備用鋼材
JP2004-324855 2004-11-09
JP2004324848A JP4571847B2 (ja) 2003-11-14 2004-11-09 金属精錬炉排ガスダクト
PCT/JP2004/017214 WO2005047555A1 (ja) 2003-11-14 2004-11-12 耐損耗性または耐損耗性およびガス切断性に優れた排煙処理設備用鋼材と排ガスダクト

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080115493A1 (en) * 2006-11-17 2008-05-22 Wolf Eric P Diesel combustion engine having a low pressure exhaust gas recirculation system employing a corrosion resistant aluminum charge air cooler
WO2009089061A1 (en) * 2008-01-09 2009-07-16 Penske Truck Leasing Co., L.P. Method and apparatus for custom cost accounting invoicing

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102791895B (zh) * 2009-12-04 2014-12-24 Posco公司 具有优异耐热性的加工用冷轧钢板及其制造方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3604376A (en) * 1969-12-16 1971-09-14 Sticker Ind Supply Corp Electric furnace ventilation and gas cooling cleaning system
US5820819A (en) * 1995-08-25 1998-10-13 Nippon Steel Corporation Steel for chimney or gas duct, excellent in pitting resistance and rust adhesion
US20040154707A1 (en) * 2003-02-07 2004-08-12 Buck Robert F. Fine-grained martensitic stainless steel and method thereof

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH09279293A (ja) * 1996-04-15 1997-10-28 Nkk Corp 耐排ガス腐食性に優れた鋼
JP3549397B2 (ja) * 1998-06-11 2004-08-04 新日本製鐵株式会社 耐食鋼
JP2000256782A (ja) * 1999-03-11 2000-09-19 Nkk Corp Ｌｎｇ燃焼排ガス流通路用鋼
JP2000256781A (ja) * 1999-03-11 2000-09-19 Nkk Corp Ｌｎｇ燃焼排ガス流通路用鋼

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3604376A (en) * 1969-12-16 1971-09-14 Sticker Ind Supply Corp Electric furnace ventilation and gas cooling cleaning system
US5820819A (en) * 1995-08-25 1998-10-13 Nippon Steel Corporation Steel for chimney or gas duct, excellent in pitting resistance and rust adhesion
US20040154707A1 (en) * 2003-02-07 2004-08-12 Buck Robert F. Fine-grained martensitic stainless steel and method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20080115493A1 (en) * 2006-11-17 2008-05-22 Wolf Eric P Diesel combustion engine having a low pressure exhaust gas recirculation system employing a corrosion resistant aluminum charge air cooler
WO2009089061A1 (en) * 2008-01-09 2009-07-16 Penske Truck Leasing Co., L.P. Method and apparatus for custom cost accounting invoicing

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WO2005047555A1 (ja) 2005-05-26

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