CN101270459A - Method for improving welded joint fatigue strength following chilling treatment after weld toe TIG refusion - Google Patents

Method for improving welded joint fatigue strength following chilling treatment after weld toe TIG refusion Download PDF

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CN101270459A
CN101270459A CNA2007101593413A CN200710159341A CN101270459A CN 101270459 A CN101270459 A CN 101270459A CN A2007101593413 A CNA2007101593413 A CN A2007101593413A CN 200710159341 A CN200710159341 A CN 200710159341A CN 101270459 A CN101270459 A CN 101270459A
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toe
tig
weld
remelting
welding
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CN101270459B (en
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史春元
丁成钢
朱平
焦建强
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Dalian Jiaotong University
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Dalian Jiaotong University
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Abstract

The invention discloses an after-welding processing method by using a welding joint after being remelted by a welding toe TIG to follow a spray chilling treatment to adjust the residual stress field of the weld toe to transfer the original residual tension stress field of the TIG remelting area into a compression stress field which is beneficial to improve the endurance strength of the joint. The method integrates both the advantages of improving the geometrical shape of the welding toe by TIG remelting and improving the residual stress state of the welding toe by the chilling treatment in the remelting area; besides, the method has the advantages of simple device, convenient operation, remarkable effect, easily checked and controlled quality, no noise, no environment pollution, etc. The method can be applied to the non-quenching steels like mild steel low alloyed steel, etc., as well as the welding structures of the metals like aluminum alloy and titanium alloy. The method can be popularized and applied in the industrial fields of shipping and ocean platforms, rolling stocks, railroad bridges, cranes, oil pipelines and chemical containers.

Description

The method of toe of weld TIG remelting heel improving welded joint fatigue strength following chilling treatment
Technical field
The invention belongs to welding technique and engineering field, the welded construction that relates generally to soft steel, low alloy steel is improved a kind of after welding treatment method of welded joint fatigue strength by adjusting toe of weld surface residual stress field.
Background technology
Toe of weld TIG remelting (molten repairing) technology is a kind of after welding treatment method of improving welded joint fatigue strength that International Institude of Welding (IIW) is recommended, this method is to be thermal source with the tungsten argon arc, with the toe of weld refuse, defectives such as the undercut that removing may exist, micro-slag inclusion, form the uniform reflow zone of transition simultaneously, make between weld seam and the mother metal and realize rounding off, reduce stress concentration, improve the fatigue strength of joint.Compare with other processing method that improves welded joint fatigue strength, it is simple that TIG remelting technology has technology, easy to use, cheap, do not have an advantage such as noise, therefore be applied at industrial circles such as shipbuilding and ocean platform, rail truck, railroad bridge, lifting machine, oil pipeline, pressures vessels for the chemical industry.
But, after utilizing TIG electric arc that toe of weld is reheated fusing, cooled and solidified, the toe zone still presents high residual-tensile stress state, make that the effect of improving joint fatigue strength is restricted greatly, the degree that the fatigue strength of butt junction simultaneously improves also exists marked difference, the fatigue data discreteness is big, sometimes even exist to reduce the possibility of joint fatigue strength.Therefore eliminating the toe of weld residual tension is the key that addresses the above problem.The method that tradition is eliminated unrelieved stress mainly contains oscillating aging processing (VRS) and the processing of integral solder structure stress relief annealing.The former needs specific equipment, and the effect of removal unrelieved stress is very limited; It is better that the latter eliminates the effect of unrelieved stress, and power consumption is big, efficient is low but integrally annealed is handled.For large welded structures, as bridge, hull, ocean platform etc., adopting these two kinds of methods to carry out bulk treatment objectively also is being impossible realize.
Summary of the invention
The objective of the invention is: handle with the spray Quench by toe of weld TIG remelting heel and adjust the residual stress field, toe zone, make the residual tension on toe of weld surface change two-way compressive stress state into, thereby improve the fatigue strength of welding joint greatly, improve the reliability and the work-ing life of welded construction safe operation.
Technical scheme of the present invention is: in the toe zone of welding joint (butt joint or corner connection), with TIG electric arc toe of weld is carried out heat fused, when reflow zone under air naturally cooling, solidify and when dropping to certain temperature, water sprays processing as heat-eliminating medium to remelted layer, this district's metal is promptly shunk form two-way stress field.The concrete steps of the method for toe of weld TIG remelting heel improving welded joint fatigue strength following chilling treatment are:
(1) handle before, remove lip-deep iron rust of toe of weld and splash earlier, the cleaning of polishing gently of available in case of necessity emery wheel;
(2) be that thermal source carries out remelting according to pre-set processing parameter along toe of weld with TIG electric arc, the angle between arc axis and the plummet is 0 °~30 °, and is positioned at 0.5mm~1.5mm place, the toe of weld outside;
(3) when toe of weld TIG reflow zone temperature was reduced to more than the critical temperature 100 ℃~200 ℃, water sprayed processing as low-temperature receiver to reflow zone, the temperature adjustment of TIG reflow zone when low-temperature receiver intensity is handled according to material, thickness of slab and Quench;
(4) after toe of weld TIG reflow zone Quench is handled, weldment is dried in case get rusty.
Toe of weld TIG remelting processing parameter is: the tungsten electrode diameter: φ 3.2mm, and nozzle diameter: φ 12mm, shielding gas are argon gas; argon flow amount is 10~12L/min, and electric current is 170~180A, and voltage is 14~18V; speed is 13~16cm/min, and critical temperature is 450 ℃.
Toe of weld TIG remelting heel is handled the principle of regulating the residual stress field with Quench: under as-welded, weld seam and nearly seam district (comprising toe of weld) thereof are the residual tension state.Handle in the welding toe remelting with TIG electric arc, be equivalent to not add the TIG welding process of filler metal.In the heat-processed of TIG electric arc, toe of weld reflow zone heat fused forms liquid metal bath, than the effect of contraction of cool region metal, has formed uneven compressive plastic deformation around the solid metal expanded by heating of its adjacent domain, thermal expansion amount are subjected to; In process of cooling, the reflow zone liquid metal solidification is subjected to the constraint of solid metal on every side and forms residual tension when shrinking, contiguous reflow zone and this part solid metal that compressive plastic deformation taken place also are subjected to metal around it in varying degrees stretching action, finally form residual tension.As seen, toe of weld is by still being two-way residual tension field after the TIG remelting.
When after toe of weld TIG reflow zone is solidified, being reduced to a certain temperature, using water as the Quench source toe of weld reflow zone surface is sprayed processing, the reflow zone and the contiguous position that are tensile stress state are shunk rapidly.When string stress overcame the yield strength of material under this temperature, reflow zone produced the stretching plastic deformation.If the reflow zone temperature surpasses a certain threshold value, then its stretching plastic deformation has also remained stretching plastic deformation's amount when all offsetting original compressive plastic deformation amount.When toe of weld reflow zone cool to room temperature, this remaining stretching plastic deformation is subjected to the rigidity squeezing action of metal on every side and forms two-way residual compressive stress field.
If it is Tcr that toe of weld TIG reflow zone is carried out the critical temperature of Quench processing, then
When T<Tcr, reflow zone is the residual tension state
When T>Tcr, reflow zone is the residual compressive stress state
When T=Tcr, reflow zone is stressless criticality
For the Q345 structural low welding assembly of thickness 14mm, the critical temperature value Tcr that toe of weld TIG reflow zone is carried out the Quench processing is 450 ℃.
Advantage of the present invention is: 1) handle by the Quench to toe of weld TIG electric arc reflow zone, can form the residual compressive stress field on the toe of weld top layer, improved the fatigue strength of welding joint significantly; 2) this processing method has been taken into account the TIG remelting and is improved toe of weld geometrical shape and reflow zone Quench and handle and improve toe of weld residual stress state advantage separately, and it is simple, easy to operate to have equipment, effect is remarkable, quality is checked and control easily, there is not noise, advantage such as free from environmental pollution is easy to promote the use of; 3) can replace toe of weld grinder buffing technology and postwelding one-piece construction annealing method, increase substantially production efficiency, reduce energy consumption and manufacturing cost; 4) applied widely.Not only can be used for non-hardened steel such as ordinary low-carbon steel, structural low, also can promote the use of in metallic substance such as aluminium alloy, titanium alloys.Can be applicable in industries such as boats and ships, machinery, vehicle, metallurgy, oil, chemical industry.
Description of drawings
The invention will be further described below in conjunction with the drawings and specific embodiments.
Fig. 1 is that toe of weld TIG remelting heel is with Quench treatment process process synoptic diagram
Embodiment
Embodiment 1
Quench treatment process after the toe of weld TIG remelting of configuration in railroad truck welded frame T shape corner joint.Material selection Q345-C structural low (thickness 14mm), toe of weld TIG remelting processing parameter: tungsten electrode diameter phi 3.2mm, nozzle diameter φ 12mm, argon flow amount 10L/min, electric current 170~180A, voltage 14~18V, speed 13~16cm/min.During the TIG remelting, the angle of welding torch and riser is about 30 °, and arc axis is positioned at 1~1.5mm place, the toe of weld outside.Toe of weld TIG remelted layer Quench treatment process: toe of weld TIG remelted layer temperature drops to when being not less than 500 ℃, the current that will have certain pressure spray toe of weld reflow zone surface by special nozzle and carry out the Quench processing, leave suitable distance between water jet and the tig torch, be not less than 500 ℃ to guarantee spray position remelted layer temperature.Adopt the result of blind hole method test welding toe unrelieved stress: under as-welded, the σ x=167MPa of parallel bead direction, the σ y=126MPa of vertical weld direction; After the toe of weld TIG remelting, σ x=161MPa, σ y=67MPa; Spray is handled during toe of weld TIG remelting postcooling to 550 ℃, σ x=-176MPa, σ y=-123MPa.Obviously, handle the back by this processing method and form two-way stress field in the toe zone.Fatigue test results shows, compares with as-welded, and the fatigue strength of T connector has improved 1.2 times.
Embodiment 2
Quench treatment process after the toe of weld TIG remelting of sheet material opposite joint.Material selection 16MnR low alloy steel (thickness 14mm), toe of weld TIG remelting and remelted layer Quench treatment process parameter are identical with embodiment 1.During the TIG remelting, the vertical test piece for welding of welding torch, arc axis is positioned at 0.5~1.0mm place, the toe of weld outside.The unrelieved stress test result is: under as-welded, and σ x=215MPa, σ y=164MPa; After the toe of weld TIG remelting, σ x=155MPa, σ y=129MPa; Spray is handled during toe of weld TIG remelting postcooling to 550 ℃, σ x=-209MPa, σ y=-198MPa.As seen, handle the back by this processing method and also be formed with the bi-directional compression stress field that is beneficial to raising fatigue strength in the toe zone.

Claims (2)

1, the method for toe of weld TIG remelting heel improving welded joint fatigue strength following chilling treatment is characterized in that step is:
(1) handle before, remove lip-deep iron rust of toe of weld and splash earlier, the cleaning of polishing gently of available in case of necessity emery wheel;
(2) be that thermal source carries out remelting according to pre-set processing parameter along toe of weld with TIG electric arc, the angle between arc axis and the plummet is 0 °~30 °, and is positioned at 0.5mm~1.5mm place, the toe of weld outside;
(3) when toe of weld TIG reflow zone temperature was reduced to more than the critical temperature 100 ℃~200 ℃, water sprayed processing as low-temperature receiver to reflow zone, the temperature adjustment of TIG reflow zone when low-temperature receiver intensity is handled according to material, thickness of slab and Quench;
(4) after toe of weld TIG reflow zone Quench is handled, weldment is dried in case get rusty.
2, the method for toe of weld TIG remelting heel improving welded joint fatigue strength following chilling treatment according to claim 1; it is characterized in that; described toe of weld TIG remelting processing parameter is: tungsten electrode diameter: φ 3.2mm; nozzle diameter: φ 12mm, shielding gas are argon gas, and argon flow amount is 10~12L/min; electric current is 170~180A; voltage is 14~18V, and speed is 13~16cm/min, and critical temperature is 450 ℃.
CN2007101593413A 2007-12-29 2007-12-29 Method for improving welded joint fatigue strength following chilling treatment after weld toe TIG refusion Expired - Fee Related CN101270459B (en)

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CN102151960A (en) * 2010-12-31 2011-08-17 陕西国德电气制造有限公司 Automatic TIG (Tungsten Inert Gas) remelting forming method of weld joints in aluminum alloy shell
CN102770227A (en) * 2011-02-23 2012-11-07 新日本制铁株式会社 Manufacturing method for welded joint and welded joint
CN102831274A (en) * 2012-08-30 2012-12-19 中南林业科技大学 Correction method of distribution of quenching stress field of aluminum alloy thick plate
CN102941401A (en) * 2012-10-30 2013-02-27 太原理工大学 Method for welding ferritic stainless steel with trailing intense cooling
CN103111759A (en) * 2013-02-02 2013-05-22 鞍山煜宸科技有限公司 Method of improving fatigue strength of aluminum alloy welding joint
CN104690401A (en) * 2015-02-16 2015-06-10 天津大学 Quenching type pulsation welding method
CN106513942A (en) * 2017-01-12 2017-03-22 南京工程学院 Magnesium alloy weld joint surface nanocrystallization device and method
CN111444645A (en) * 2020-03-09 2020-07-24 扬州大学 Port machine damage positioning method based on residual stress gap state
CN112589238A (en) * 2020-12-02 2021-04-02 上海江南长兴造船有限责任公司 Method for improving fatigue strength of CM (CM) node of LNG (liquefied Natural gas) ship
CN114012218A (en) * 2021-10-15 2022-02-08 沪东中华造船(集团)有限公司 Postweld treatment method for prolonging service life of ship structure
CN114075642A (en) * 2021-11-18 2022-02-22 曲作鹏 Water-cooled wall induction fusion welding following type surface strengthening method

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CN102151960A (en) * 2010-12-31 2011-08-17 陕西国德电气制造有限公司 Automatic TIG (Tungsten Inert Gas) remelting forming method of weld joints in aluminum alloy shell
CN102770227A (en) * 2011-02-23 2012-11-07 新日本制铁株式会社 Manufacturing method for welded joint and welded joint
US20130153092A1 (en) * 2011-02-23 2013-06-20 Nippon Steel Corporation Method of production of welded joint
CN102831274A (en) * 2012-08-30 2012-12-19 中南林业科技大学 Correction method of distribution of quenching stress field of aluminum alloy thick plate
CN102941401A (en) * 2012-10-30 2013-02-27 太原理工大学 Method for welding ferritic stainless steel with trailing intense cooling
CN102941401B (en) * 2012-10-30 2015-02-25 太原理工大学 Method for welding ferritic stainless steel with trailing intense cooling
CN103111759A (en) * 2013-02-02 2013-05-22 鞍山煜宸科技有限公司 Method of improving fatigue strength of aluminum alloy welding joint
CN104690401B (en) * 2015-02-16 2016-08-24 天津大学 A kind of quenching pulsation welding method
CN104690401A (en) * 2015-02-16 2015-06-10 天津大学 Quenching type pulsation welding method
CN106513942A (en) * 2017-01-12 2017-03-22 南京工程学院 Magnesium alloy weld joint surface nanocrystallization device and method
CN106513942B (en) * 2017-01-12 2019-06-25 南京工程学院 A kind of magnesium alloy face of weld nanocrystallization device and method
CN111444645A (en) * 2020-03-09 2020-07-24 扬州大学 Port machine damage positioning method based on residual stress gap state
CN111444645B (en) * 2020-03-09 2023-06-20 扬州大学 Harbor machine damage positioning method based on residual stress gap state
CN112589238A (en) * 2020-12-02 2021-04-02 上海江南长兴造船有限责任公司 Method for improving fatigue strength of CM (CM) node of LNG (liquefied Natural gas) ship
CN114012218A (en) * 2021-10-15 2022-02-08 沪东中华造船(集团)有限公司 Postweld treatment method for prolonging service life of ship structure
CN114075642A (en) * 2021-11-18 2022-02-22 曲作鹏 Water-cooled wall induction fusion welding following type surface strengthening method

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