焊缝余高指焊缝表面两焊趾连线上的那部分金属高度，通俗的说，余高指的是鼓出母材表面的部分或角焊末端（即焊趾）连接线以上部分的熔敷金属。

Weldreinforcementreferstotheheightofthepartofmetalontheconnectinglinebetweenthetwoweldingtoesontheweldsurface.Generallyspeaking,reinforcementreferstothepartprotrudingfromthebasemetalsurfaceorthedepositedmetalabovetheconnectinglineattheendoffilletwelding(i.e.weldingtoe).

焊缝余高的利与弊

Advantagesanddisadvantagesofweldreinforcement

利：在焊接过程中应该有焊缝，因为这一层起到保温缓冷的作用，对细化晶粒、降低焊接应力有很大作用，同时也是气孔等杂质的聚集区，弊：压力容器不希望有突变，导致局部应力集中，另外余高有缺陷，这种缺陷很可能是产生疲劳裂纹的核，裂纹源→疲劳扩展→断裂，试验表明，有余高的设备比打磨后没有余高的设备使用寿命短2.0～2.5倍。

Advantages:thereshouldbeweldintheweldingprocess,becausethislayerplaysaroleofheatpreservationandslowcooling,whichhasagreatroleinrefininggrainandreducingweldingstress,anditisalsotheaccumulationareaofimpuritiessuchaspores.Disadvantages:thepressurevesseldoesnotwanttohavemutation,whichleadstolocalstressconcentration.Inaddition,thereinforcementhasdefects,whichmaybethecoreoffatiguecrack,cracksource→fatiguepropagationThetestshowsthattheservicelifeoftheequipmentwithreinforcementis2.0-2.5timesshorterthanthatoftheequipmentwithoutreinforcementaftergrinding.

控制措施

controlmeasures

1.壁厚较大的钢管应开坡口：对于壁厚大于14.3毫米的钢管，应开X形坡口并预焊，如果预焊条件不成熟，则应在内焊后用气刨清根，或砂轮自动磨削清根，或铣削清根等方法，将外焊缝在未焊之前加工成U形槽再进行焊接。

1.Thesteelpipewithlargerwallthicknessshouldbebeveled:forthesteelpipewithwallthicknessgreaterthan14.3mm,theX-shapedgrooveshouldbebeveledandprewelded.Ifthepreweldingconditionisnotmature,theouterweldshouldbeprocessedintoU-shapedgroovebeforeweldingbyairgouging,grindingwheelautomaticgrindingormilling.

2.调整好焊接线能量：检查焊缝能量是否合适，一般用焊接接头的酸腐蚀样来检查，一是检查内外焊缝的重合量的程度，二是检查焊道腰部的宽窄，对重合量的规定一般是大于1.5mm，但内外焊缝的重合量以1.3~3.0mm较合适，高过3.0mm则意味着线能量大了。

2.Adjusttheweldinglineenergy:checkwhethertheweldinglineenergyisappropriate.Generally,theacidcorrosionsampleoftheweldingjointisusedtocheck.Oneistochecktheoverlapdegreeoftheinternalandexternalwelds,andtheotheristocheckthewidthoftheweldbeadwaist.Theoverlapamountisgenerallygreaterthan1.5mm,buttheoverlapamountoftheinternalandexternalweldsis1.3~3.0mm,higherthan3.0mmmeansthatthelineenergyislarge.

线能量大，不但熔深大，焊缝的余高也大，如不开坡口或U形槽，焊缝余高就更大，这是因为焊接线能量越大，单位时间内熔化的焊丝越多，对于高强度钢，应严格控制焊接线能量，焊接高强度钢板时，为了降低各层的线能量，一般采用多道焊（2道以上），焊缝的形状系数应在1.3~2.0mm内。

Thelargertheweldinglineenergyis,themoreweldingwiresaremeltedperunittime.Forhigh-strengthsteel,theweldinglineenergyshouldbestrictlycontrolled.Inordertoreducethelineenergyofeachlayer,multipasswelding(morethan2passes)isgenerallyadoptedwhenweldinghigh-strengthsteelplate,andtheweldinglineenergyshouldbestrictlycontrolledTheshapefactorshouldbewithin1.3-2.0mm.

3.多丝焊时宜采用较细的前丝：采用多丝焊时，如果原外焊三丝直径匹配为4mm+3.2mm+3.2mm，则需要将前丝改为Ф3.2mm较好，因为在相同的电流下，使用Ф3.2mm的焊丝比使用Ф4mm的焊丝熔深大，也就是说前丝采用Ф3.2mm的焊丝，即便降低一些线能量，也可以到达采用Ф4mm时同样的熔深效果，这是因为细丝的电流密度大于粗丝。

3.Whenusingmultiwirewelding,itisbettertousethinnerfrontwire:ifthediameteroftheoriginalexternalweldingthreewiresis4mm+3.2mm+3.2mm,itisbettertochangethefrontwiretoФ3.2mm,becauseunderthesamecurrent,thedepthoffusionofthewirewithФ3.2mmisgreaterthanthatofthewirewithФ4mm,thatistosay,thewirewithФ3.2mmcanreachthesamelevelwhenusingthewirewithФ4mm,evenifsomelineenergyisreducedThisisbecausethecurrentdensityoffinewireishigherthanthatofthickwire.

经验证明，在其他条件不变的情况下，采用Ф3.2mm的前丝要比Ф4mm的前丝熔深大20％左右，这在外焊不开坡口或不刨凹槽时所减少的外焊缝余高效果更明显，但当焊接壁厚大于14.3mm的钢管，前丝电流在A左右时，应使用4mm的前丝，否则可能影响电弧的稳定燃烧。

Experiencehasprovedthat,undertheconditionofotherconditionsunchanged,thepenetrationdepthofthefrontwirewithdiameterof3.2mmisabout20%greaterthanthatofthefrontwirewithdiameterof4mm,whichismoreobviouswhenthegrooveisnotopenedorthegrooveisnotplaned.However,whentheweldingwallthicknessisgreaterthan14.3mmandthecurrentofthefrontwireisabouta,thefrontwirewithdiameterof4mmshouldbeused,otherwisethestable

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