|Title of Invention||
A METHOD FOR MANUFACTURING A CORROSION-RESISTANT CLAD STEEL PLATE
|Abstract||Disclosed are a corrosion-resistant clad steel plate and its manufacturing method.The corrosion-resistant clad steel plate having excellent mechanical bonding force in heterogenous metals can be manufactured by tack-whlding a thin strip of Fe- or Ni-based amrophous alloy as a binder onto one side or both side caebon steel plate and seamwelding a corrosion-resistant metal plate such as an alloy of nickel or titanium onto the binder to produce a corrosion-resistant clad steel plate;or alternatively,produced by tack-weldimg a thin strip of Fe- or Ni-based amorphous alloy as afirst binder onto one side or both sides of a carbon steel plate, tack-welding a thin strip of an alloy of nickel or stainless steel and copper as a second binderonto the thin strip and seam-welding a corrosion-resistant metal plate such as an alloy nickel or titanium onto the binder.|
|Full Text||FORM 2 THE PATENT ACT, 1970
"ft m£THOD FOR MANUFACTURING CORROSION-RESISTANT
CLAD STEEL PLATE " 1: "CORROSION RESISTANT ^CLAD STEEL riiATE AND
ITS E1ANUFACTURING METHOD?"
2. (a) Ju-Yong JUNG -
(b) 9-906, Woosung APT, #83, Dowha-dong, Mapo-gu,
Seoul, Republic of Korea. (c) Nationality Korean Individual.
The following specification particularly describes the nature of the invention and the manner in which it is to be performed.
CORROSION-RESISTANT CLAD STEEL PLATE AND ITSMANUFACTURING METHOD
The present invention relates to a corrosion-resistant clad steel plate, in particular, a corrosion-resistant clad steel plate having excellent mechanical bonding force in heterogeneous metals and its manufacturing method.
In contrast to general medal"s, corrosion-resistant materials, such as alloys of titanium (Ti) , zirconium (Zr) , tantalum (Ta) , niobium (Nb) and nickel, are difficult to weld and also very expensive, and thus are not generally used in the industry. However, such metals having corrosion-resistance, light weight, excellent strength may be used in various fields-, though being restricted in their range of uses. In the fields requiring excellent corrosion-resistant materials, such as chemical plants,- environmental facilities and so on, the clad steel plates comprising the corrosion-resistant materials bonded to inexpensive carbon steel plates have been widely used because of their economic benefit, convenience in use, and various utilities. Various clad steel plates are manufactured by several methods. For example, a hot rolling method is responsible for a roll bond
clad plate and an explosive welding method for an explosive welded clad plate. Additionally, a resistance seam welding method is useful to manufacture a clad plate.
In a preparation technique of a roll bond clad plate by a hot rolling method, a.corrosion-resistant alloy layer with excellent corrosion resistance comprising nickel alloy or nickel-copper alloy or titanium alloy on a carbon steel plate as a base metal is simultaneously heated, and then hot-rolled at high temperature through a roller. As such,v it is not. a favorable technique from the viewpoint of manufacturing cost.
In contrast to the roll bond clad plate by hot rolling, a technique for forming a clad steel plate by an explosive welding method uses explosion energy of blasting powders for bonding, and thus has somewhat superior bonding force to that of the roll bond. However, this technique has disadvantages of having more expensive manufacturing costs and requiring longer preparation time than the roll bond and limitations of sizes of the clad steel plates, and dangers in the work place associated with explosive powders.
In order to solve the above-mentioned problems economically and simply, a method for manufacturing the clad steel plafes by use of a resistance seam welding has been developed. - In this method, metals are welded by use of the heat generated by the electric resistance when a large quantity of current flows in the metals, in accordance with a principle invented by James Joule. There have been proposed attempts to bond heterogeneous metals by such a resistance
seam welding. For instance, a thin strip or netting of copper alloy and stainless steel as the binder is intercalated into the carbon steel plate and the steel plate of the corrosion-resistant nickel alloy or titanium steel plate and then seara-welded. But this process " suffers from limitations in use because of poor bonding force.
Accordingly, an object of the present invention for alleviating the problems as described above is to provide a clad plate consisting of a corrosion-resistant material and a carbon steel not only being inexpensive but only having excellent bonding force in heterogeneous metals, and its manufacturing method.
The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which:
FIG. 1 is a schematic diagram illustrating a corrosion-resistant clad plate of the present invention to be welded by a resistance welder consisting of two circular electrodes.
FIG. 2 is a sectional perspective view of a clad plate
of the present invention.
Based on the present invention, the above objects can be achieved by tack-welding a thin strip of Fe- or Ni-based amorphous alloy as a binder onto one side or both sides of a carbon steel plate and seam-welding a corrosion-resistant metal plate"such as an alloy of nickel or titanium onto the binder to produce a corrosion-resistant clad steel plate.
Alternatively, a corrosion-resistant ciad steel plate can be produced by tack-welding a thin strip of Fe- or Ni-based amorphous alloy as a first binder onto one side or both sides of a carbon steel plate, tack-weiding a thin strip of an alloy of nickel or stainless steel and copper as a second binder onto the thin strip and seam-welding a corrosion-resistant metal plate such as an alloy of nickel or titanium onto the binder.
The thin strip of Fe- or Ni-based amorphous alloy is used as the binder of a middle layer between the corrosion-resistant material and the base metal (usually, carbon steel). Accordingly, heterogeneous metals can be bonded together by virtue of characteristics of the amorphous alloy, while clad steel plate with excellent bonding force can be manufactured.
The reason why the Fe- or Ni-based amorphous alloy is used as a first binder is that, because the Fe- or Ni-based
amorphous "alloy is deficient in a slip system, which is usually found in structural crystals, but retains a free volume resulting from random atom arrangement, it is of high strength with high ductility as well as showing such high electric resistance as to generate great heat upon seam welding, a kind of resistance welding, thereby bringing about excellent bonding force.
Commonly, Fe- or Ni-based amorphous thin strip has higher electric resistance and better ductility and fluidity than those of general materials so that, when conducting resistance seam welding, it may be bonded, with no dependence on shape of materials or forms of their surfaces. Also, because the Fe- or Ni-based amorphous thin strip is unstable at normal temperatures but crystallizes at about 300-500 °C, when seam-welded at about 1000 °C or higher, its welded portions form stable structures, thereby forming a clad plate with superior bonding force and mechanical strength.
Alternatively, in order to obtain a clad steel plate having better bonding force and mechanical strength, a second binder with high strength, including nickel or stainless steel, may be laminated onto the first binder at the same time, and then! seam welded to manufacture clad steel plates comprising heterogeneous metals with high strength.
Referring to Fig. 1, the" clad ..steel plate of the present invention is manufactured by laminating a thin
nickel strip 3, as the second binder, onto the amorphous thin strip 2, as the first binder, interposing the laminated layer between the corrosion-resistant metal plate 4 and the base metal 1, and then seam-welding via circular electrodes 5. The method of the present invention has far superior bonding force to that .of conventional methods in which only a thin strip of nickel alloy is seam-welded, or wire netting, copper netting, stainless netting and the like are laminated onto the nickel alloy thin strip before conducting the seam welding. As such, the best seam-welding, may be carried out, with suitable control of pressing pressure, current and period of time in accordance with- kinds- and thickness of the corrosion-resistant materials, the binders and the carbon steel materials.
Turning now to Fig. 2, there is shown a clad steel plate comprising the corrosion-resistant metal plate 4 bonded to the base metal 1 or the base metal 1 between the corrosion-resistant metal plates 4, in which ,seam-welded beads 6 are provided on surfaces of the clad steel plate.
In addition to bonding the corrosion-resistant materials, such as titanium (Ti), zirconium (Zr), tantalum (Ta) , niobium (Nb) and nickel, to the carbon steel, the corrosion-resistant materials can be bonded with stainless steel or copper, aluminum and so on. Further, other heterogeneous materials including nickel alloy and carbon steel, copper alloy and carbon steel, etc., may be bonded.
When the amorphous Fe- or Ni-based thin strip is used,
we expect to improve the ease of welding by making use of the thin strip further comprising elements such as boron (B) or silicon (Si), other than iron (Fe), and thus to increase the bonding strength. Additionally, to improve the bonding force and the mechanical strength of the clad steel plate, a plural number of layers of the first binder and the second binder may be used to conduct the seam welding, and flux may be also applied on the binders to increase various effects when being welded.
A better understanding of the present invention may be obtained in light of the following examples which are set forth to illustrate, but are hot to he construed to limit the present invention.
Layers of binders were interposed between a carbon steel (SS400) 6 mm thick as a base metal and-titanium 1.6 mm thick as a corrosion-resistant material. They were bonded by a resistance welder under conditions of 2 kg/mm2 of a pressing pressure, 15000-40000A of a welding current, 5-10 hours of resistance welding time and 5-10 hours of down time, to obtain a clad steel plate. The mechanical strengths of titanium clad steel plates manufactured through a method of the present invention and conventional ones are presented in Table 1, below. In Table 1, it is found that products of the present invention have superior shear strength to that
of conventional ones.
COMPARISON OF MECHANICAL STRENGTHS OF TITANIUM CLAD STEEL PLATE
Manufacturing Method Corrosion-Resistant Metal Binder 1 Binder 2 Shear Strength (Kg/mm2) Tensile Strength (Kg/mm2) Yield Strength (Kg/mm2)
Resistance Seam Welding (inventive) Ti-Gr.2 Amorphous Fe-strip Ni-strip 20.5 47.5 35.6
Ti-Gr.2 Amorphous Fe-strip Stainless Steel-strip 19 _ 47 35
Ti-Gr.2 Amorphous Fe-strip - 17.8 46.2 33
Resistance Seam Welding (conventional) Ti-Gr2 Cu-net Ni-strip 15.2 45 30
Ti-Gr2 Fe-net Ni-strip 15.2 45 30
Ti-Gr2 Stainless Steel-net Ni-strip 16 47 32
Roll Bond Ti-Gr2 - - 14.8 45 -
Explosive Welding Ti-Gr2 - - 15 45 -
International standard JIS 0601 Gr2+SS400 - >13". 98 >39..18. -
Resistance Seam Welding (inventive) Ti-Gr.l Amorphous Fe-strip Ni-strip 18.4 40.0 30.5
Ti-Gr.l Amorphous Fe-strip Stainless Steel-strip 17.5 41.0 30.8
Resistance Seam Welding (conventional) Ti-Gr.l Cu-net Ni-strip 14 39 27.3
Ti-Gr.l Fe-net Ni-strip 14 . 39 27
Ti-Gr.l Stainless Steel-net Ni-strip 16 40 28
Roll Bond Ti-Gr.l - - 14.5 40 -
* base metal SS400 6 mm .thick/titanium 1.6 mm thick
The clad steel plates were manufactured by the method of the present invention and conventional ones using nickel and nickel alloy as the corrosion-resistant materials and were measured for their mechanical strengths. From the
results shown in Table 2, below, it can be seen that the plates manufactured in accordance with the method of the present invention have superior welding strength to that of conventional plates wherein only nickel"strip is used.
COMPARISON OF MECHANICAL STRENGTHS OF NICKEL AND NICKEL ALLOY CLAD STEEL PLATE
Manufacturing Method Corrosion-Resistant
Metal Birider 1 Binder 2 Shear Strength (Kg/mm2) Tensile Strength (Kg/mm2) Yield Strength (Kg/mm2)
Resistance Seam Welding (inventive) N1200 Amorphous Ni-strip Ni-strip 30 54"" 33
Ni400 Amorphous Ni-strip Stainless Steel-strip 30 51 33
C_276 Amorphous Ni-strip Ni-strip 36 58 38.7
Ni200 Amorphous Ni"Strip - 28.5 52.2 30.3
Ni400 Amorphous Ni-strip - 28.5 49.7 30.3
C_276 Amorphous Ni-strip - 33.7 57.3 36
Resistance Seam Welding (conventional) Ni200 - Ni-strip 25.5 51 28.9
Ni400 - Stainless Steel-strip 26 50 30
C 276 Ni-strip 30 54 35.7
International Standard ASTM A265 >1.4.06
w >49.21 >28.12
* base metal SS400 6 mm thick/corrosion-resistant metal 1.6
Clad plates were manufactured by the method of the present invention and conventional ones, using zirconium, tantalum and niobium as corrosion-resistant materials and
were measured for their mechanical strengths. The results are given in Table 3. From this table, it can be seen that the clad plates have similar strength to that of the plates clad with titanium, therefore, bonding of such corrosion-resistant metals being efficiently conducted by the method of the present invention.
COMPARISON OF MECHANICAL STRENGTHS OF ZIRCONIUM, TANTALUM AND NIOBIUM CLAD STEEL PLATE
Manufacturing Method Corrosion-Resistant Metal Binder 1 Binder 2 Shear Strength (Kg/mm2) Tensile Strength (Kg/mm2) Yield Strength (Kg/mm2)
Resistance Seam Welding (inventive.) Zr702 Amorphous Fe-strip Ni-strip 20.2 47.1 31.2
Ta Amorphous Fe-strip Ni-strip 12.4 40 35
Nb Amorphous Fe-strip Ni-strip 12.4 40 35
Zr702 Amorphous Fe-strip - 18.0 45.2 27.8
Ta Amorphous Fe-strip - 10.6 38.1 31.6
Nb Amorphous Fe-strip - 10.6 38.1 31.6
Resistance Seam Welding (conventional) Zr702 Cu-net Ni-strip 15.2 45 30
Ta Cu-net Ni-strip 10.5 35 30
Nb Cu-net Ni-strip 11 34 30
■* base metal SS400 6 mm thick/corrosion-resistant metal 1.0
As shown in above examples, it can be seen that the clad steel plates manufactured by the method of the present invention are superior to conventional ones, and have excellent shear strength, directly associated with their bonding force.
The clad steel plate of the present invention having
superior bonding properties and strengths can be produced on a large scale and be used as a good substitute for conventional expensive corrosion-resistant materials. in addition, use of the clad steel plate with high strength in the work place may result in not only lengthening the expected life span of corrosion-resistant equipment, but also reducing incidental material expenses in facility preparation. Accordingly, the clad steel plate of the present invention ,is expected to have more economic benefits than conventional corrosion-resistant ones, and to have applications to various fields.
The present invention has been described in an illustrative manner, and it is to be understood that the terminology used is intended to be in the nature of description rather than of limitation. Many modifications and variations of the present invention are possible in light of the above teachings. Therefore, it is to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.
1. A method for manufacturing a corrosion-resistant clad steel plate, wherein a thin strip of Fe or Ni based amorphous alloy as a first binder is tack welded onto one side or both sides of a carbon steel plate or wherein a Ni-based thin strip as a second binder is tack-welded onto the thin strip of the Fe of Ni based amorphous alloy as the first binder, and then a corrosion resistant metal plate is seam-welded onto the binder.
2. The method as set forth in claim 1, wherein the corrosion-resistant metal plate is selected from the group consisting of titanium, zirconium, tantalum, niobium, nickel and alloys thereof.
3. The method as set forth in claim 1, wherein flux is applied to the first binder and the second binder.
Dated this 19th day of November 2001,
Dr. Rajeshkumar H. Acharya
Advocate and patent agent
For and on behalf of applicant
|Indian Patent Application Number||1102/MUM/2001|
|PG Journal Number||24/2007|
|Date of Filing||20-Nov-2001|
|Name of Patentee||JU-YONG JUNG|
|Applicant Address||9-906, WOOSUNG APT, #83, DOWHA-DONG, MAPO-GU, SEOUL, REPUBLIC OF KOREA|
|PCT International Classification Number||B 32 B 15/00|
|PCT International Application Number||N/A|
|PCT International Filing date|