CN103769728A - Process for repair-welding steel casting through flux-cored wire CO2 gas shielded welding - Google Patents

Process for repair-welding steel casting through flux-cored wire CO2 gas shielded welding Download PDF

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Publication number
CN103769728A
CN103769728A CN201410074313.1A CN201410074313A CN103769728A CN 103769728 A CN103769728 A CN 103769728A CN 201410074313 A CN201410074313 A CN 201410074313A CN 103769728 A CN103769728 A CN 103769728A
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welding
steel
casting
flux
repair
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CN103769728B (en
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卢克华
陈德苏
孙志标
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JIANGSU WANHENG CASTING INDUSTRY Co Ltd
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JIANGSU WANHENG CASTING INDUSTRY Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/04—Welding for other purposes than joining, e.g. built-up welding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/095—Monitoring or automatic control of welding parameters
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/16—Arc welding or cutting making use of shielding gas
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K9/00—Arc welding or cutting
    • B23K9/235—Preliminary treatment

Abstract

The invention relates to the cast steel industry, particularly to a process for repair-welding a steel casting through flux-cored wire CO2 gas shielded welding. During the application, the process for repair-welding steel casting products is characterized by selecting a flux-cored wire matched with a casting base material, determining welding process parameters reasonably, selecting a welding current of 150-300 A, a welding voltage of 23-40 V, a wire extension length of 15-25mm, a welding speed of 45-90 mm/s, a gas flow of 20-25 L/min, and performing WPQ (welding procedure qualification ) according to the IX volume of ASME (American Society of Mechanical Engineers). The process for repair-welding the steel casting through the flux-cored wire CO2 gas shielded welding solves the problem of low efficiency, high labor intensity, multiple joints and slag removal difficulty of manual SMAW (shielded metal arc welding), eliminates defects such as microcracks, porosity and slag inclusion of a repair-welding area, when compared with the SMAW, can improve the working efficiency to 3-5 times, reduces production costs to more than 50%, enables the hydrogen content of weld metal to be lower than 2.0 ppm and corrosion resistance to be strong, guarantees that physical and chemical properties accord with and exceed requirements of corresponding cast steel material standards, and is applicable to high-grade, precise and top-notch steel castings and steel castings of high pressure hydrogen valves.

Description

Use flux-cored wire CO 2gas is protected the technique of weldering soldering cast steel part defect
Technical field
The present invention relates to cast steel industry, about using flux-cored wire CO 2gas is protected the technique of weldering soldering cast steel part defect, applies this process for repairing steel-casting product, has solved stick electrode arc welding efficiency low, joint is many, scarfing cinder difficulty, and welder's labour intensity is large, a high in cost of production difficult problem, has eliminated and in soldering district, has been prone to the defects such as micro-crack, pore, slag inclusion.The 3-5 that can increase work efficiency doubly, reduces production costs more than 50%, and in weld metal, hydrogen content is lower than 2.0ppm, and resistance to corrosion is strong.Be applicable to high, precision and frontier end steel-casting, high-pressure hydro Valve Steel Castings, improve quality of welding repair, increase Strong high temperature resistant, high pressure resistant, corrosion-resistant, anti-hydrogen attack performance, met the requirement of safe and reliable use under special operation condition.
Background technology
Cast steel industry mainly adopts stick electrode arc welding to carry out soldering to the defect of steel-casting, welding rod material and the mother metal selected match, format diameter is Φ 2.5-Φ 5mm, before using, to be baked to the temperature of regulation according to the explanation of welding rod, insulation a period of time could be carried out soldering to casting defect position, stick electrode arc welding efficiency is low, joint is many, scarfing cinder difficulty, cost is high, and labour intensity is large, is prone to the new defect such as micro-crack, pore, slag inclusion in soldering district, be unfavorable for high, precision and frontier end steel-casting, high-pressure hydro Valve Steel Castings improves quality of welding repair.
Summary of the invention
The object of this invention is to provide-kind use flux-cored wire CO 2gas is protected the technique of weldering soldering cast steel part defect, applies this process for repairing steel-casting product, has solved stick electrode arc welding efficiency low, and joint is tired, scarfing cinder difficulty, and the high difficult problem of cost, has eliminated and in soldering district, has been prone to the defects such as micro-crack, pore, slag inclusion.The 3-5 that can increase work efficiency doubly, reduces production costs more than 50%, and welding block hydrogen content is lower than 2.0ppm, and resistance to corrosion is strong.Be applicable to high, precision and frontier end steel-casting, high-pressure hydro Valve Steel Castings improve quality of welding repair, increase Strong high temperature resistant, high pressure resistant, corrosion-resistant, anti-hydrogen attack performance, met the requirement of safe and reliable use under special operation condition.
     
Technical solution of the present invention is: use flux-cored wire CO 2the technique of gas shielded arc welding soldering cast steel part defect,---qualification of welding procedure---physicochemical property check---defect cleaning---foundry goods preheating (having needs)---rewelding---interlayer temperature control---post weld heat treatment (having needs)---the Non-Destructive Testing surface treatment of---polishing and clear up---that its flow process is: welding wire, test specimen are prepared; The content of main critical process is:
Welding wire, test specimen are prepared: select the flux-cored wire of corresponding material according to steel-casting quality of parent material,
It is Φ 1.2-Φ 1.6mm plate-like silk that specification adopts straight warp conventionally; (seeing the following form)
Figure 2014100743131100002DEST_PATH_IMAGE001
Welding piece is of a size of 350mm × 150mm × 30mm, and test specimen adopts butt welding, downhand position;
Qualification of welding procedure: carry out according to ASME IX rollback request, select rational welding condition scope to be: welding current: 150-300A, weldingvoltage: 23-40V, extension elongation: 15-25mm, weldering speed: 45-90mm/s, gas flow: 20-25L/min, after finishing, welding carries out radiographic inspection inspection, then intercept physicochemical property sample, to meet or exceed the physicochemical property of foundry goods mother metal be qualified to physicochemical property after testing, work out successively weld procedure specification, for instructing the soldering of corresponding cast steel part defect, evaluate the defective rewelding that must not instruct corresponding steel-casting,
Physicochemical property check: mainly refer to the chemical composition of butt welded seam, mechanical property, intercrystalline corrosion, grain size, ［ N ］, ［ H ］, ［ O ］ gas content, ferrite contents etc. detect;
Defect cleaning: refer to steel-casting is removed through the local defect of Non-Destructive Testing discovery, equipment is mainly used carbon arc air gouging, emery wheel etc., defect must be removed thoroughly, surface cleaning;
Foundry goods preheating (have and need): for some carbon steels, alloy steel casting, carbon equivalent C e≤ 0.4% material can not preheating be carried out soldering, for steel-casting carbon equivalent C e=0.4-0.6% material can low-temperature prewarming 100-200 ℃ be carried out soldering, for steel-casting carbon equivalent C e>=0.6% material wants preheating 300-500 ℃ to carry out soldering;
Rewelding: must strictly be undertaken by qualified weld procedure specification requirement;
Interlayer temperature control: interlayer temperature when soldering must not be higher than the requirement of weld procedure specification;
Post weld heat treatment (have and need): for needing post weld heat treatment, undertaken by WPS welding procedure card request, eliminate welding stress, prevent crackle;
Non-Destructive Testing: refer to steel-casting local defect is carried out carrying out RT after soldering, PT or MT detect, and new defect is removed or produced to whether focus detection.
Polishing cleaning: smooth transition is answered in the cleaning of soldering surface finish, must not have cut, localized burn phenomenon.
Good effect of the present invention is: the flux-cored wire that soldering is used does not need baking, and the 3-5 that increases work efficiency doubly, has reduced labour intensity, saves production cost more than 50%, and in weld seam, hydrogen content is lower than 2.0ppm, and resistance to corrosion is strong.
The specific embodiment
The implementation process of this technique is described as an example of the soldering of ASME SA-351/351M CF8M valve casting defect example.
Its physicochemical property is chemical composition C≤0.08%, Si≤2.00%, Mn≤1.50%, P≤0.04%, S≤0.04%, Cr=18-21%, Mo=2-3%, Ni=9-12%.Mechanical property: tensile strength >=485Mpa, yield strength >=205Mpa, percentage elongation >=30%.
1, welding wire, test specimen are prepared: selecting the flux-cored wire standard of corresponding material according to steel-casting quality of parent material is AWS A5.22.The welding wire trade mark is E316LT1-1, and it is Φ 1.2mm plate-like silk that specification adopts straight warp, CO 2gas concentration is 99.95%.
2, qualification of welding procedure: carry out according to ASME IX rollback request.Welding piece is of a size of 350mm × 150mm × 30mm, and test specimen adopts butt welding, and downhand position, selects rational welding condition, welding method FCAW, and power supply type and polarity are DC +, 28 ℃ of preheat temperatures, interlayer temperature 90-130 ℃, flame heating, range of choice is: welding current is 140-200A, weldingvoltage 24-35V, extension elongation 15-25mm, weldering speed is: 45-90mm/s, gas flow 15-25L/min.Method is to use the identical test specimen of same foundry goods mother metal, adopt butt welding, after finishing, welding carries out radiographic inspection inspection, intercept in welded joints physics and chemistry sample, to meet or exceed the physicochemical property of foundry goods mother metal be qualified to physicochemical property after testing, establishment weld procedure specification, for instructing the soldering of corresponding cast steel part defect.
3, physicochemical property check: the chemical composition C:0.032% of weld seam, Si:0.58%, Mn:1.27%, P:0.0017%, S:0.008%, Cr:18.40%, Mo:2.31%, Ni:11.54%.Mechanical property: tensile strength 565Mpa, yield strength 565Mpa, percentage elongation 42%, 30J when impact value-196 ℃.Intercrystalline corrosion is up to the standards, and grain size is more than 8 grades, gas content ［ N ］≤100ppm, ［ H ］≤2ppm, ［ O ］≤50ppm, and ferrite content is 8%.
Foundry goods preheating: because CF8M steel-casting welding performance is good, preheat temperature is 28 ℃, and room temperature is carried out soldering, and interlayer temperature is controlled at 90-130 ℃.Welding point hardness detects as 140-165HV.
4, defect cleaning: refer to steel-casting is removed through the local defect of Non-Destructive Testing discovery, with carbon arc air gouging, thoroughly removal of defects surface cleaning.
5, rewelding: must strictly be undertaken by the WPS weld procedure specification requirement of evaluation.
6, interlayer temperature control; The requirement of ℃ regulation of interlayer temperature 90-130 when soldering.
7, post weld heat treatment: for the post weld heat treatment of CF8M material steel-casting, adopt solution heat treatment, be heated to 1080 ± 14 ℃, temperature retention time is greater than 3 hours.
8, Non-Destructive Testing: refer to steel-casting local defect is carried out carrying out PT, RT Non-Destructive Testing after soldering again, whether focus detection removal of defects or soldering district produce new defect.
9, polishing cleaning: smooth transition is answered in the cleaning of soldering surface finish, must not have cut, localized burn phenomenon, iron preventing pollution.

Claims (1)

1. use flux-cored wire CO 2the technique of gas shielded arc welding soldering cast steel part defect,---qualification of welding procedure---physicochemical property check---defect cleaning---foundry goods preheating (having needs)---rewelding---interlayer temperature control---post weld heat treatment (having needs)---the Non-Destructive Testing surface treatment of---polishing and clear up---that its flow process is: welding wire, test specimen are prepared; The content of critical process is:
Welding wire, test specimen are prepared: select the flux-cored wire of corresponding material according to steel-casting quality of parent material,
It is Φ 1.2-Φ 1.6mm plate-like silk that specification adopts straight warp conventionally; (seeing the following form)
The mother metal trade mark AWS standard Welding wire model GB/T standard Welding wire model CF3、CF8 A5.22 E308LT1-1 GB/T17853 E308LT1-1 CF3M、CF8M A5.22 E316LT1-1 GB/T17853 E316LT1-1 CF8C A5.22 E347LT1-1 GB/T17853 E347LT1-1 CG3M、CG8M A5.22 E317LT1-1 GB/T17853 E317LT1-1 WC6 A5.29 E81T1-B2C GB/T17493 E551T1-B2C WC9 A5.29 E91T1-B3C GB/T17493 E621T1-B3C C5 A5.29 E81T1-B6C GB/T17493 E551T1-B6C WCA、WCB、WCC A5.20 E701T-1C GB/T10045-2001 E501T-1
Welding piece is of a size of 350mm × 150mm × 30mm, and test specimen adopts butt welding, downhand position;
Qualification of welding procedure: carry out according to ASME IX rollback request, select rational welding condition scope to be: welding current: 150-300A, weldingvoltage: 23-40V, extension elongation: 15-25mm, weldering speed: 45-90mm/s, gas flow: 20-25L/min;
Foundry goods preheating (have and need): for some carbon steels, alloy steel casting, carbon equivalent C e≤ 0.4% material can not preheating be carried out soldering, for steel-casting carbon equivalent C e=0.4-0.6% material can low-temperature prewarming 100-200 ℃ be carried out soldering, for steel-casting carbon equivalent C e>=0.6% material wants preheating 300-500 ℃ to carry out soldering.
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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104191066A (en) * 2014-09-01 2014-12-10 江苏政田重工股份有限公司 Cast steel repair welding process
CN104259632A (en) * 2014-07-10 2015-01-07 扬帆集团股份有限公司 Tail fin welding process of 10000-ton level bulk cargo ship
CN104439876A (en) * 2014-09-29 2015-03-25 宁夏共享铸钢有限公司 Method for repairing defects of pipe orifice of high-alloy hollow valve shell casting
CN104532104A (en) * 2014-12-31 2015-04-22 青田中天铸造阀门有限公司 Technology for preventing cast piece made of CF8C material from cracking
CN105382432A (en) * 2014-08-12 2016-03-09 洛阳九创重型机械有限公司 Defect mending technology for heavy-duty metal castings
CN108356436A (en) * 2017-12-28 2018-08-03 江苏朗锐茂达铸造有限公司 A kind of steel-casting process for welding repair Reliability Assessment Method
CN108637428A (en) * 2018-05-18 2018-10-12 共享铸钢有限公司 A kind of high intensity gear ring class cast steel part defect weldering repair renovation method
CN108918219A (en) * 2018-06-30 2018-11-30 武汉冶钢结构有限责任公司 The preparation method of non-destructive testing with dreg defect weld seam simulating test pieces
CN110270744A (en) * 2018-03-13 2019-09-24 江苏万恒铸业有限公司 Mechanization gas metal-arc welding valve body connect Welding with valve seat
CN110303297A (en) * 2019-07-02 2019-10-08 浙江开诚机械有限公司 CrMoV steel-casting reprocesses repair method

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU1412896A1 (en) * 1985-12-24 1988-07-30 Ульяновский Завод Тяжелых И Уникальных Станков Method of machine cold electric arc welding of cast iron
JPS6462275A (en) * 1987-09-02 1989-03-08 Ural Politekhn Inst Method of repairing surface of steel part
CN1935441A (en) * 2006-10-16 2007-03-28 四川东风电机厂有限公司 Water-wheel generator rotor support hub defect treatment method
CN102248262A (en) * 2011-06-20 2011-11-23 江门市新会区同达化工机械制造有限公司 Welding repair process method for cast steel kettle rings of autoclaved kettle and cover edge cracks
CN102756235A (en) * 2012-07-23 2012-10-31 苏州热工研究院有限公司 Field welding repair method especially for larger and penetrating defects in steel casting with heavy wall thickness

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SU1412896A1 (en) * 1985-12-24 1988-07-30 Ульяновский Завод Тяжелых И Уникальных Станков Method of machine cold electric arc welding of cast iron
JPS6462275A (en) * 1987-09-02 1989-03-08 Ural Politekhn Inst Method of repairing surface of steel part
CN1935441A (en) * 2006-10-16 2007-03-28 四川东风电机厂有限公司 Water-wheel generator rotor support hub defect treatment method
CN102248262A (en) * 2011-06-20 2011-11-23 江门市新会区同达化工机械制造有限公司 Welding repair process method for cast steel kettle rings of autoclaved kettle and cover edge cracks
CN102756235A (en) * 2012-07-23 2012-10-31 苏州热工研究院有限公司 Field welding repair method especially for larger and penetrating defects in steel casting with heavy wall thickness

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
生利英: "ZG35过渡垫块裂纹的补焊修复", 《焊接技术》 *
生利英: "轮带裂纹的修复补焊工艺", 《铸造技术》 *

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN104259632A (en) * 2014-07-10 2015-01-07 扬帆集团股份有限公司 Tail fin welding process of 10000-ton level bulk cargo ship
CN105382432A (en) * 2014-08-12 2016-03-09 洛阳九创重型机械有限公司 Defect mending technology for heavy-duty metal castings
CN104191066A (en) * 2014-09-01 2014-12-10 江苏政田重工股份有限公司 Cast steel repair welding process
CN104439876A (en) * 2014-09-29 2015-03-25 宁夏共享铸钢有限公司 Method for repairing defects of pipe orifice of high-alloy hollow valve shell casting
CN104532104A (en) * 2014-12-31 2015-04-22 青田中天铸造阀门有限公司 Technology for preventing cast piece made of CF8C material from cracking
CN104532104B (en) * 2014-12-31 2016-08-17 青田中天铸造阀门有限公司 A kind of CF8C material foundry goods chap preventing process
CN108356436A (en) * 2017-12-28 2018-08-03 江苏朗锐茂达铸造有限公司 A kind of steel-casting process for welding repair Reliability Assessment Method
CN110270744A (en) * 2018-03-13 2019-09-24 江苏万恒铸业有限公司 Mechanization gas metal-arc welding valve body connect Welding with valve seat
CN108637428A (en) * 2018-05-18 2018-10-12 共享铸钢有限公司 A kind of high intensity gear ring class cast steel part defect weldering repair renovation method
CN108637428B (en) * 2018-05-18 2020-10-27 共享铸钢有限公司 Repair welding repair repairing method for defects of high-strength gear ring type steel castings
CN108918219A (en) * 2018-06-30 2018-11-30 武汉冶钢结构有限责任公司 The preparation method of non-destructive testing with dreg defect weld seam simulating test pieces
CN110303297A (en) * 2019-07-02 2019-10-08 浙江开诚机械有限公司 CrMoV steel-casting reprocesses repair method

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