【Key words】 Industrial pure nickel((Nickel 200)/Process qualification /Welding quality
Nickel 200 has excellent corrosion resistance in certain media, it is the best material for heat-resistant concentrated alkali solutions. It is also very resistant to neutral slightly acidic solutions and organic solvents. It has high strength and plasticity, especially in a cold and hot state, it has good processing performance. Therefore, pure nickel is often used in acid-base devices in the petrochemical industry to achieve anti-corrosion effects.
1. Kev ntsuas kev ua haujlwm vuam ntawm Nickel 200
Lub purity ntawm kev lag luam ntshiab npib tsib xee feem ntau yog siab dua 99 feem pua, nws cov feem ntau ntawm cov ntawv xov xwm tsis pub tshaj 1 feem pua. Lub ntsiab qauv yog austenite, lub ntsej muag -centered cubic lattice, uas yog ze rau austenitic stainless hlau. Tus txheeb ze ntom ntom yog ze rau ntawm tooj liab, uas yog 8.9g / ml.
Lub melting point ntawm npib tsib xee yog qis dua li ntawm titanium thiab cov pa roj carbon tsawg, cov thermal conductivity qis dua cov pa roj carbon steel, thiab cov hluav taws xob tiv taus siab dua. Ntshiab Ni welds tsis dhau theem kev hloov pauv thaum lub sij hawm solidification, thiab feem ntau tsim coarse dendritic austenite crystals. Tsawg melting point impurities S, P, Pb, thiab lwm yam ntsiab lus tsim ib tug tsawg melting point eutectic ntawm lub grain ciam teb, ua rau thermal tawg. Ntshiab ni muaj cov khoom me me -kua theem kub ntau thiab fluidity tsawg. Nws yog ib qho yooj yim rau yaj H2, O2, CO2, thiab lwm yam gases nyob rau hauv lub xeev ua kua. Thaum cov roj no tsis khiav hauv lub sijhawm, cov pores yuav tsim.
Tsis tas li ntawd, vim muaj kev tiv thaiv siab thiab tsis tshua muaj thermal conductivity, nws yog ib qho yooj yim rau overheat thaum lub sij hawm vuam, uas ua rau kev loj hlob sai ntawm weld nplej, uas cuam tshuam rau cov khoom siv thiab corrosion kuj ntawm cov pob qij txha.
2. Welding txheej txheem tsim nyog
Welding procedure qualification is carried out in accordance with JB/T4756-2006 "Nickel and Nickel Alloy Pressure Vessels" and JB/T4745-2002 "Titanium Welding Vessels" Appendix B.
2.1 Welding consumables thiab test piece npaj
Cov txheej txheem tsim nyog tau txais phau ntawv tungsten argon arc vuam (TIG), lub hauv paus hlau yog kev lag luam ntshiab npib tsib xee (N6), vuamNickel 200 hlau is ERNi-1 material of ф2.4mm, and the size of the test piece is 400mm300mm6mm. Compared with low alloy steel, pure ni welding has the characteristics of low permeability, but large line energy cannot be used to increase the permeability. The groove form should choose a large groove angle, the angle is 75 degree , the blunt edge is 1mm, Gap 2mm.
2.2 Cov txheej txheem vuam txheej txheem npaj
Nyob rau hauv kev saib ntawm cov yam ntxwv ntawm N6 uas tsis muaj thermal conductivity, yooj yim overheating, thiab yooj yim txoj kev loj hlob ntawm weld nplej, lub vuam txheej txheem tsis, tshwj xeeb tshaj yog kev tswj ntawm kab zog, yuav tsum nruj me ntsis tswj. Kev xyaum tau ua pov thawj tias txoj kev txo cov vuam tam sim no ib leeg tsis yog qhov ua tau zoo tshaj plaws, vim tias cov kua nickel muaj cov dej tsis zoo thiab qhov nkag mus tob, thiab qhov tseeb tam sim no yuav tsum tsis txhob tsawg dhau. Lub tshav kub input tuaj yeem tswj tau los ntawm kev nce qhov vuam ceev thiab qhov kub ntawm qhov interlayer tuaj yeem tswj tau nruj me ntsis raws li qhov ua kom ntseeg tau qhov sib xyaw ntawm cov vuam.
2.3 Cov qhab nia xeem
Tom qab ua tiav daim ntawv xeem tiav, kev tshuaj xyuas qhov chaw vuam, RT tsis yog -kev tshuaj ntsuam xyuas kev puas tsuaj thiab kev tshuaj ntsuam xyuas ntawm microscopic metallographic yog ua tom qab muab tso rau hauv chav sov li 24 teev. Cov kev soj ntsuam tau pom tias muaj qhov pores nyob rau hauv qhov chaw weld, thiab tsis muaj cov kab nrib pleb tsis pom qhov tsis zoo.
3 .Kev soj ntsuam cov txiaj ntsig kev xeem
Nws tuaj yeem pom los ntawm cov txiaj ntsig kev xeem uas vim muaj cov ntsiab lus tsawg heev ntawm S thiab P impurities hauv vuamNickel 200 hlau, tus naj npawb ntawm tsawg -melting eutectics tshwm sim los ntawm cov txheej txheem vuam yog me me, yog li tsis muaj kub tawg, cov kab hluav taws xob yog tswj tsis pub dhau 10kJ / cm, thiab nyob rau hauv vuam hlau Al thiab Ti yog alloying ntsiab uas refine cov nplej, thiab tsis muaj grain coarsening phenomenon.
