A HIGH HARDNESS AND WEAR-RESISTING FLUX CORED WIRE

Abstract: A high hardness and wear-resisting flux cored wire, wherein said core includes (in wt.%): molybdenum 1-10; tungsten 1-10; graphite 1-10; nickel 1-7; vanadium 2-10; chromium 20-40; sodium silicon fluoride (Na 2 SiF 6 ) 5-15; niobite 1-10; boron 10-15; quartz 2-10; rare earth 1-8. These components are ground into powder and stirred thoroughly and then placed onto a steel strip with a thickness of 0.25-0.6 mm. The steel strip is extruded by an extrusion press into a wire which is finally drawn out by a wire drawing machine, and the high hardness and wear-resisting flux cored wire is thus obtained. The wire can be used for repairing welding cold roll with a hardness of HRC 62-65 without cracks.

Description: Technical Field of the Invention The present invention relates to a high hardness and wear-resisting flux cored welding wire, and particularly to a welding wire for repairing and welding cold roll. Background Art R. KILLING et.al.: "Zum Ablauf der Legierungsvorgänge beim Auftragsschweissen mit selbstschützenden Fülldrahtelektroden" SCHWEISSEN UND SCHNEIDEN., vol. 36, no. 7, July 1984 (1984-07), pages 309-315, XP002143789 DEUTSCHE VERLAG FÜR SCHWEISSTECHNIK. DÜSSELDORF., DE ISSN: 0036-7184 discloses a welding wire comprising a flux core, including SiO 2 , TiO 2 , CaCO 3 , CaF 2 , NaAlF, Al 2 O 2 , MgO, CaO, K 2 O. The conventional stack welding material is mainly made of rare and noble metals, such as nickel, chromium, ferroniobium, cobalt, etc., as main ingredients and of carbon as additional composition. The prior art has the defects that the source of the material is insufficient and that the cost is high. On the other hand, carbon is used for enhancing the hardness, however, cracks appears when the hardness reaches to HRC 58. Even if quenching process is performed to enhance the hardness, the hardness may only reach to HRC 58 and the failure rate is high, which results in waste. As for cold roll, its hardness shall reach to over HRC 60. Some American specialists drew a conclusion that it is impossible for stack welding material to reach HRC 60. Sovinient experts also had an opinion that it is normal and certain for stack welding material to produce cracks when its hardness reaches to HRC 60. A welding wire which is made of tungsten carbide, available from Stellite Welding Material Co. Ltd. (Shanghai), has a hardness of only HRC 52-58. Cracks appear when the hardness is higher. A stack welding flux cored wire made of tungsten carbide; available from Jingluo Welding Wire Company in Luohe city of Henan Province in China, of the type TL-8705, has a hardness of HRC 52-58. Cracks appear when the hardness is higher. Moreover, the hardness of the two kinds of stack welding material mentioned above is enhanced by quenching, but it still can not reach to HRC 60, their maximum hardness being only HRC 58. The quenching time is long and electricity consumption is high, as a result, its cost will increase. This kind of stack welding material can only be used for hot roll. As for repairing cold roll, there is still not suitable stack welding material so far. Object of the Invention It is an object of the invention to provide a high hardness and wear-resisting flux cored wire in order to overcome the foregoing defects. The hardness of the wire can reach to HRC 62-65, even to HRC 66-69, and it can be used for repairing cold roll. Therefore, it has high values. It is another object of the invention to provide a method for manufacturing a high hardness and wear-resisting flux cored wire. Wire made by this method can be used for repairing cold roll. Summary of the Invention In order to achieve the above objects, according to one aspect of the present invention, there is provided with a high hardness and wear-resisting flux cored welding wire comprising a flux core and a skin layer, wherein the flux core has a composition in weight percentage comprising. molybdenum 1-10%; tungsten 10-1%; graphite 10-1%; nickel 1-7%; vanadium 10-2%; chromium 40-20%; sodium silicon fluoride 5-15%; ferroniobium 10-1%; boron 10-25%; silica sand 2-10%; rare earth 1-8%. The diameter of the wire is about 1.0-4.0 mm. The skin layer is of a thickness of 0.25-0.6 mm, which is made of low carbon steel, preferably of low carbon steel H08A. According to another aspect of present invention, there is provided with a method for manufacturing a high hardness and wear-resisting flux cored wire, comprising the steps of preparing a raw material of a flux core according to the composition defined above, and grinding the raw material into a flux core powder and stirring thoroughly; preparing a low carbon steel strip and placing said flux core powder onto the steel strip; extruding and pressing the obtained structure into a cylindrical wire; and drawing said cylindrical wire with a wire drawing machine and obtaining the wire. The wire can be used for repairing and welding cold roll without cracks at ambient temperature. Its mechanical performance meets the standard requirement. After repaired and welded, the roll is machined with a lathe or a grinder to achieve a required dimension. Advantages of the Invention Compared with the prior art, the high hardness and wear-resisting flux cored wire of the present invention has the following advantages: 1. practical for repairing and welding cold roll with high economic valuables; 2. no crack; 3. high hardness of HRC 62-65, even to HRC 66-69, and good wear-resistance; 4. simple process and low cost. Detailed Description of Preferred embodiments Embodiment 1 Prepare a raw material of the composition in wt.% as follows: molybdenum 10%; tungsten 1%; graphite 1%; nickel 7%; vanadium 2%; chromium 20%; sodium silicon fluoride 15%; ferroniobium 1%; boron 25%; silica sand 10%; rare earth 8%. Grind these materials into power, stir thoroughly, and place onto a low carbon steel (H08A) strip with a thickness of 0.3 mm. Wind and press the obtained structure into a cylindrical wire with an extrusion apparatus. Then, draw out with a wire drawing machine, and a wire with a diameter of 1.0-4.0 mm is thus obtained. Embodiment 2 Prepare a raw material of the composition in wt.% as follows: molybdenum 1%; tungsten 10%; graphite 5%; nickel 1%; vanadium 10%; chromium 40%; sodium silicon fluoride 5%; ferroniobium 10%; boron 1%; silica sand 2%; rare earth 1%. Grind these materials into power, stir thoroughly, and place onto a low carbon steel (H08A) strip with a thickness of 0.5 mm. Wind and press the obtained structure into a cylindrical wire with an extrusion apparatus. Then, draw out with a wire drawing machine, and a wire with a diameter of 4 mm is thus obtained. Embodiment 3 Prepare a raw material of the composition in wt.% as follows: molybdenum 5%; tungsten 8%; graphite 3%; nickel 8%; vanadium 7%; chromium 39%; sodium silicon fluoride 13%; ferroniobium 6%; boron 9%; silica sand 5% and rare earth 4%, grind these components into powder and stir thoroughly and place onto a low carbon steel (H08A) strip with a thickness of 0.5 mm. Grind these materials into power, stir thoroughly, and place onto a low carbon steel (H08A) strip with a thickness of 0.5 mm. Wind and press the obtained structure into a cylindrical wire with an extrusion apparatus. Then, draw out with a wire drawing machine, and a wire with a diameter of 4 mm is thus obtained. It is proved from the experiment of repairing and welding cold roll with the welding wire described in the three embodiments mentioned above that the hardness of each wire is greater than HRC 62 and is of good repairing results.

Claims: A high hardness and wear-resisting flux cored wire comprising a flux core and a skin layer, wherein the flux core has a composition in weight percentage consisting of: molybdenum 1-10%; tungsten 10-1%; graphite 10-1%; nickel 1-7%; vanadium 10-2%; chromium 40-20%; sodium silicon fluoride 5-15%; ferroniobium 10-1%; boron 10-25%; silica sand 2-10%; rare earth 1-8%, the skin layer consisting of low carbon steel. A wire according to claim 1, characterized in that said skin layer is made of low carbon steel H08A with a thickness of 0.6 mm. A wire according to claim 1 or 2, characterized in that the composition of said flux core is molybdenum 10%; tungsten 1%; graphite 1%; nickel 7%; vanadium 2%; chromium 20%; sodium silicon fluoride 15%; ferroniobium 1%; boron 25%; silica sand 10%; rare earth 8%. A method for manufacturing a high hardness and wear-resisting flux cored wire, comprising the steps of preparing a raw material of a flux core according to the composition defined in claim 1, and grinding the raw material into a flux core powder and stirring thoroughly; preparing a low carbon steel strip and placing said flux core powder onto the steel strip; extruding and pressing the structure obtained into a cylindrical wire; and drawing said cylindrical wire with a wire drawing machine and obtaining the wire. A method according to claim 4, characterized in that said steel strip is made of low carbon steel H08A. A method according to claim 4, characterized in that the diameter of said wire is 1.0-4.0 mm. A method according to claim 4, characterized in that the flux core has a composition of molybdenum 10%; tungsten 1%; graphite 1%; nickel 7%; vanadium 2%; chromium 20%; sodium silicon fluoride 15%; ferroniobium 1%; boron 25%; silica sand 10%; rare earth 8%.

Inventors: PAN GUOXI, PAN, GUOXI
Applicants: PAN GUOXI, PAN, GUOXI
Application year: 1997
Main classification: B23K35
IPC codes: B23K35