Sou Yuhui, zhao GuifengAbstract This Paper Introduced The Welding Technology Of Plasma Arc Welding For Pure Titanium.
It Analyzied The Keypoints Of Welding Quality For Titanium And Pointed Out The Protective Measures Of The Welding Pool And Welding Zone, and Also Improved The Protective Cover And Nozzle.
As A Results, obtained A Satisfied Welding Joint Under The Using The Reasonable Specification.
Keywords Pure Titanium Plasma Arc Welding Protective Cover Nozzle0 is introductive my factory trial-produce homebred produce per year ammonia of 300 thousand tons of synthesis the first set of whole set of equipment, the CO2 strip tower in producing per year equipment of form a complete set of 240 thousand tons of urea among them, use below high temperature, high pressure, burn-in condition, this strip tower used indigenous industry pure titanium to make liner material. Ply of titanium of line of room of strip tower high pressure is 5mm and 10mm two kinds, material brand is TA1 industry pure titanium, current, of titanium material solder to basically use arc of tungsten pole argon to solder, plasma solder has energy concentration, penetration is strong, bosseyed solder is double-faced shape, groove preparation is simple, quality stability and manufacturing efficiency are advanced a lot of advantages. Be aimed at plasma of industrial pure titanium the characteristic of solder, undertook experimenting study, the titanium that uses plasma arc solder successfully at strip tower board liner solders, include to seal head and tube plate explosive answer is operable the joining together of pieces of 5mm is big titanium board, and 5, 10mm is thick flat-fell seam of flat of body of canister of titanium board liner and canister body are shut of N-joining solder, solder quality achieves design requirement. 1 solder equipment uses LH-300 plasma arc is automatic welder, distribute power supply of commutate of silicon of Z × G-300. Plasma welding torch is the new-style welding torch that designs by oneself, used homocentric degree adjustable but tungsten of discharge type water-cooling extremely, shrink inside tungsten pole successive and adjustable wait for a structure, make of gun put oneself in another's position sealed and adjust reliable and handy, the treatment of gun put oneself in another's position is made also simplify greatly, improved the dependability that gun put oneself in another's position uses and life. Arc welding torch already was in this kind of new-style plasma the product solders in underwent test. 2 solder the safeguard of titanium needs to protect temperature prep above in the light of titanium the area of 300 ℃ this one characteristic, solder special protector was designed in the experiment. 2.
Besides the protective mouth that 1 protection pulls a cover to be had besides welding torch itself, still need to procrastinate on welding torch hang special protection to pull a cover. Original the box type that we use groovy argon arc solder to use pulls a cover. The blaze that goes out from bath reflex as a result of plasma arc column sheds temperature tall, easy burn out copper wire, convert the thin copper that digs concentrated alveolus replaces cupreous network, pulling a cover two side secure two to get together fender of 4 fluorine ethylene, fender is clingy mobile on workpiece, this increased to protect the effect not only, and still solved pull the insulation issue between cover and workpiece. Pull a cover through improvement protection with this kind (graph 1) solder 5 millimeter are thick titanium board, welding line and hot influence area all are silvery white, protective result is favorable. Solder 10 millimeter titanium board when, use the protection that the graph shows a structure 1 times to pull a cover, protective result is bad. Since the place that bring arc, inside the welding line length with about 150 long millimeter, the surface shows dark gray, welding line also shows the different oxidation color such as yellow Lan Zi inside the others length, only place of welding line ending shows silvery white. Although pull cover course to be improved for many times to protection, still short of grants its effect. Analysing 10 millimeter thick titanium board the account that welding line produces exterior oxidation quality, think because weldment ply increases,its basically are, solder hot capabilities adds, solder contact area comes loose heat is slow, cooling inadequacy breaks away from protection and cause. Be based on this one analysis, design the water refrigeration with a kind of unique structure to protect slide block (graph 2) . It has protective effect already, the quantity of heat that can have not enough time weldment to come loose more quickly again is taken away very big one part. Make clear through be being used for a long time, the protective result of water-cooling protection slide block is favorable, and pull a cover to save the argon energy of life of 40% than the protection that designs formerly. The following experiment and production solder in, replaced protection completely to pull a cover, use at soldering 5 millimeter and 10 millimeter thick titanium board. 2.
2 protection bolster plate is protected closely besides need of welding line front outside, also need to try to be protected technically to welding line the reverse side. A few argon that the alveolus that sheet relies on to be formed by plasma arc crosses are angry, can't have protective effect to the reverse side. We were designed set the steel bolster plate that has copper (graph 3) , connect argon to protect welding line from the reverse side, the effect is very good. The copper pipe that connects argon slants a side of groove of buy bolster plate, it is to avoid to be burned out by penetrable plasma arc. The product solders the structure that uses bolster plate and graph are shown 3 times identical. Its length is 3200 millimeter, the copper pipe of the gas that connect argon divides two paragraphs, from bolster plate two end connect argon protection respectively. After using afore-mentioned welding torch and water-cooling protection slide block and protective bolster plate, two sides of welding line positive and negative all can be protected adequately, weld zone region all can achieve silvery white. 3 solder preparation works 3.
Clear before 1 solder solder when titanium, solder mouth two side must keep clear of inside certain distance everything is smeary reach exterior oxidation layer. We use pickling or machinery clears two kinds clear method. Clear with machinery the method is more simple. Machinery clears the method is as follows: With mouth of acetone eliminate solder two side inside 100 millimeter smeary, with eliminate of fine emery cloth two side the oxidation layer inside 50 millimeter, till show clean metal till, reoccupy cotton is arenaceous dip in acetone swabs 2 ～ 3 times, can undertake soldering. Pickling already was passed before fill welding wire leaves factory, before using, swab with acetone only. Clear with afore-mentioned machinery after the method clears, ion of iron of the groove before solder pollutes examination qualification, solder hind contains the analytic outcome that Fe measures to welding line, completely contented also requirement (express 1) . 3.
The 2 straight edge groove that assemble requirement solder mouth to fasten machining to go out, neater. When soldering considering the product, inevitable meeting existence assembles clearance and bad side. For this pair of clearance 0 ～ 1.
5 millimeter, the 0 ～ side the fault 1.
5 millimeter and two kinds of circumstances put those who fall in the condition to try at the same time board, undertook soldering experimenting. Use the standard that expresses 2 kinds 3 solder, speed of fill welding wire is 96 meters / when, all attainable transfer flowing and full welding line. This shows, solder when titanium, had not begged those who father to assemble a condition. 4 welder art pulling force of the surface below condition of melt of parameter pure titanium is larger, at the same time fluidity very good. The plasma arc that character of this kind of physics makes its are helpful for using keyhole effect solders, produce cut phenomenon not easily, welding line easily figuration, solder the process is stable, solder the standard changes inside bigger range, can get the welding line of figuration. 4.
1 5 millimeter is thick the welder of titanium board art parameter 5 millimeter are thick titanium board is used cylindrical nozzle solders, have two kinds of proper standards (watch 2) : The first kind of normative solder fast low, welding line is broad; The 2nd kind of normative solder fast tall, welding line is narrow, but tall to the in be opposite requirement of welding line. With the nozzle that contains 60 ° enlarge to put part (graph 4) , can hold concurrently cylindrical nozzle two kinds of normative advantages: Solder fast can rise, welding line is right in the requirement is inferior, welding line is formed beautiful. So, solder 5 millimeter are thick titanium board basically used 60 ° spray head. Use solder the standard sees a table 2. When adding fill welding wire to solder, two side all have welding line by the side of the bite with different level, after adding a few fill welding wire, eliminated completely bite an edge. 4.
2 10 millimeter is thick of titanium board solder standard 5 millimeter are thick titanium board uses 60 ° nozzle to solder have solder speed the merit with artistic figuration of tall, welding line. But solder voltaic comparing is cylindrical nozzle should be gotten greatly much. As a result of the limitation of power source capacity, 10 millimeter are thick titanium board still is used cylindrical nozzle solders, normative parameter sees a table 3. Millimeter of watch 3 10 is thick titanium board plasma arc solders parameter the 5 notes in soldering 5.
1 repeat heating influence original, the welding line when having fill welding wire to keep clear of the phenomenon side the bite of two side, collect in order to to compress lesser 90 ～ welding line of remelting of electric arc of plasma of 150 small electric current bites side position. The result discovers welding line reachs the close grain that seam an area to be brought up apparently. Bend test makes clear, via the connect of remelting, angle of bend sometimes short of 180 ° (D=3a) . Remelting 5 connect, apparent little gap can see when bend test. Accordingly, should strict control solders hot standard, reduce welding line to reach seam an area to be in nearly high temperature retention period, be opposite less as far as possible welding line undertakes repetition heating. Consider product measure is larger, solder the possibility that limitation produces in the process avoids absolutely hard, reason regulation allows local to welding line repair twice. Right now, although plasticity is reduced somewhat, but still achieve 90 ° of ≥ of angle of bend (D=3a) design requirement. 5.
The 2 halves that be out of shape the stretch model amount that controls titanium steel, all is in below similar welding stress requirement, of generation solder be out of shape want than steel one times bigger. When plasma arc solder, because be solder fully whole board thick, be heated of two sides of positive and negative is evener, its horn is out of shape should compare argon arc solder small much. We are in joining together diameter a head answer of 2800 millimeter when layer board, did not use special clamping apparatus, pressed the Fang Gang of 100 millimeter of a 100 × in welding line a side only, another side relies on section 40 × the impaction of solder car orbit of 300 millimeter, be out of shape after solder not quite, satisfied requirement of compound of the explosion that seal a head. 5.
3 weld defects solder below normal circumstance when titanium, produce weld defects not easily commonly. Because solder,we had been encountered only voltaic cost is too low and the stomatic blemish of generation. With the standard that expresses 2 kinds 3 solder a makeup of head answer layer of 5 millimeter when (welding line is about 3 meters long) , solder the meeting in the process is reduced because of network voltage, solder when voltaic on the low side reachs 235, successive and petty in-house stoma arises on face of crystallization of welding line center. Via using normal and normative new fusion welding hind, eliminated this kind of flaw. In addition, special attention answers when soldering of aperture of welding torch nozzle and groove juncture in be opposite, can cause welding line the reverse side otherwise the blemish of local incomplete fusion, this is the particularly dangerous drawback that has pointed gap. When the blemish of existence incomplete fusion, solder is weighed in must be opposite. 6 solder the function of contact 6.
Condition of 1 product technology is right solder the requirement of contact (1) TA1 titanium board the chemical component of welding line divides Fe ≤ 0.
08% outside, other should be close to mother capable person. (2) tensile test and result of test of normal temperature concussion must not are worth under the regulation of mother capable person. (3) 90 ° of ≥ of cold curved experiment (D=3a) (4) solder the main organization of contact is α photograph, β photograph and α ′ are controlled accordingly least, do not allow to contain γ photograph (5) light of 100%X of welding line classics examines, quality standard should accord with " of standard of flaw detection of ray of JB4730-94" welding line to set Ⅱ stage. (6) the surface is checked not allow has any break, stoma and deepness to be more than 0.
By the side of the bite of 5 millimeter. 6.
Titanium of 2 connect quality the classics after board solder examines, each mechanical function all achieves a requirement, welding line is single-phase α organization, without α 1 wait for brittleness photograph. The chemical composition of welding line and mother capable person is eligible. Ray of X of the classics after solder examines to did not discover any flaw. Satisfy products plan requirement completely, contact quality is good. 7 conclusion (1) slide block of protection of designs welding torch, water-cooling and protective bolster plate, contented industry is pure titanium board plasma arc solders the requirement of craft, can obtain protection good, the welding line with beautiful figuration. (2) examine from mechanical function, metallographic, in light of the result that chemical analysis and X ray flaw detection examine, choose solder normative parameter is reasonable, can contented products plan asks. (3) plasma arc solders can solder appears weldment whole ply, improved productivity greatly. With 10 millimeter thick titanium board for exemple, compare solder of arc of tungsten pole argon to be able to improve efficiency 5 ～ 6 times. In the meantime, inferior to operation competence requirement of the solderer, quality is stable, it is an advanced welder that is worth to be popularized energetically art. CNC Milling