Austenitic stainless steel welding characteristics: welding process chhunga elastic leh plastic stress leh strain te hi a lian hle a, mahse cold crack erawh hmuh tur a awm lo. Weld-ah hian quenching hardening zone leh grain coarsening a awm lo a, chuvangin weld tensile strength hi a sang hle.
Austenitic stainless steel welding-a harsatna lian ber berte: welding lian lo tak deformation; A grain boundary characteristics leh trace impurities (s, P) thenkhat a sensitivity avang hian hot crack siam a awlsam hle.
Austenitic stainless steel hmanga welding lama harsatna lian tham leh enkawlna tehfung
01 Chromium carbide siam hian weld-in intergranular corrosion a do theihna a ti tlem a ni.
Intergranular corrosion: Chromium depletion theory ang chuan, chromium carbide chu grain boundary-ah a precipitate a, weld leh heat-affected zone chu sensitization temperature zone 450-850°C-a tihlum a nih chuan, chromium-depleted grain boundaries a awm a, chu chu spirrosion dona tur a ni lo.
(1) Target material-a weld seam leh sensitization temperature zone-a corrosion inkar a corrosion tihtlem nan a hnuaia hmalaknate hi hman theih a ni:
ani. Base metal leh weld-a carbon awm zat tihtlem la, CR23C6 siam loh nan MC siamnaah dah pawimawh ber turin base metal-ah stabilizing elements TI, NB leh element dangte dah tel bawk ang che.
b. Weld chu austenite leh ferrite tlemte dual-phase structure siam tir rawh. Weld-a ferrite engemaw zat a awm chuan buhfai chu a hmin thei a, thlai chi chu a pung thei a, buh chi boundary unit area khata chromium carbide precipitation chu tihtlem theih a ni bawk.
Chromium hi ferrite ah chuan a inthiar thei hle. CR23C6 hi chromium-ah austenite grain boundary a tlakchhiat loh nan ferrite-ah hian a duh zawk a; Austenites inkar a ferrite darh hian grain boundary zawh zawnga corrosion chu a chhung lam diffusion thlengin a veng thei a ni.
c. Sensitization temperature range-a awm hun chhung control. Welding thermal cycle chu siamrem a, a theih ang anga 600～1000°C-a awm hun chu ti tawi la, energy density sang tak nei welding method thlang la (Plasma Argon Arc Welding ang chi) welding heat input tlem zawk thlang la, weld hnung lamah argon gas hmang la, copper pad hmang la, arc started chu a awm lo ang, arc started chu a awm lo ang. Multilayer welding lai hian medium chu a hnuhnung ber atan weld tur a ni.
d. Welding zawhah solution treatment emaw stabilization emaw annealing (850～900°C) leh air cooling te chu carbide charge out leh chromium diffusion ti chak turin ti rawh).
(2) Weld-te chu chemte ang maia chhem. Hemi avang hian a hnuaia preventive measures te hi tih theih a ni:
Carbon diffusion theihna chak tak avang hian grain boundary-ah a inthen darh ang a, cooling process laiin supersaturated state a siam ang a, TI leh NB te erawh chu diffusion ability hniam vangin crystal-ah an awm reng ang. Sensitization temperature range-a weld a lum leh chuan supersaturated carbon chu crystals inkar ah CR23C6 angin a precipitate ang.
ani. Carbon awm zat tihtlem. Stainless steel stabilizing elements awmna tan chuan carbon content chu 0.06% aia tam a ni tur a ni lo.
b. Welding process tling tak hmang rawh. Welding heat input tlem zawk thlang la, overheated zone awmna hun chu temperature sang takah tihtlem la, welding process chhunga 'medium temperature sensitization' effect awm loh nan ngaihven rawh.
Double-sided welding a nih chuan, corrosive medium nena inzawm weld chu weld hnuhnung ber tur a ni (hei hi a ni, pawn lam welding hnua large-diameter thick-wall welded pipe chhunga welding neih thin chu a ni). A hman theih loh chuan welding specification leh weld shape chu siamrem tur a ni a, corrosive medium nena inzawm overheated area chu pumpelh tum la, sensitized leh heated a ni leh ang.
c. Post-weld heat hmanga enkawlna. Welding zawhah solution emaw stabilization emaw hmanga enkawlna kalpui thin ang che.
02 Stress Corrosion A chhe lai a ni.
Stress corrosion cracking lo awm loh nan a hnuaia hmalaknate hi hman theih a ni:
ani. Material dik taka thlang la, weld composition chu a remchan dan angin siamrem rawh. High-purity chromium-nickel austenitic stainless steel, high silicon chromium-nickel austenitic stainless steel, ferritic-austenitic stainless steel, high-chromium ferritic stainless steel, etc. te hian stress corrosion resistance tha tak an nei a, Weld metal hian a austenitic a nei a, chu chu ferrite steel-a ferrite-a ferrite-a ferrite-a ferrite leh ferrte-a ferrite-a ferrite-a ferrite leh ferrite-te ferrite-a ferrite leh ferrite-te ferrite-a ferrte-a a awm dan a ni.
b. Residual stress tihbo emaw tihtlem emaw. Post-welding stress-relieving heat treatment atan pawh hman theih a ni a, chu chu A rilru a hah lutuk chuan a rilru a buai em em a, a rilru a hah lutuk chuan a rilru a buai em em bawk a. Annealing Furnace induction heating principle hmangtu a ni. annealing furnace eng tak chu . HAGAO Tech (Seko machinery) hian preheating a mamawh lo va, annealing temperature tha ber thlen thuai theih nan second 15 chauh a ngai a ni. Chutih rual chuan air tightness sang zawk a nei bawk a, chu chuan annealing laiin air backflow a veng tha thei hle. Annealed welded pipe hian uniform metal structure a nei a, intergranular stress chu a te zawk bawk. Chu bakah, mechanical method hrang hrang, polishing, shot peening leh hammering te hian surface residual stress a ti tlem thei bawk.
c. A rilru a hah lutuk a, a rilru a buai em em bawk. stress concentration lian tak awm lo turin.
