Hangao Tech (Seko Machinery), kum 20 chhung zet chu 2018 siam leh siamchhuahna lama tawnhriat nei tawh a ni. Stainless steel industrial welded pipe production line equipment , chuan welding process chhunga welding heat-affected zone dinhmun hrang hrang leh weld quality a nghawng dan hriatthiamna a pe ang che.
Welding-a heat-affected zone (Haz) chu weld nen a danglam hle. Welding seams te chu a performance mamawh a nih theih nan base metal-a chemical composition hmangin welding, redistribute leh welding process dik tak siam theih a ni. Mahse, chemical composition hmanga heat-affected zone hnathawh dan tur siamrem theih a ni lo. Thermal cycling hnathawh hnuaia awm chauh tissue distribution inang lo tak buaina a ni. General welded structures atan chuan embrittlement, toughening, hardening, leh heat-affected zone softening chungchang palite chu ngaihtuah ber a ni a, chubakah mechanical property kimchang, fatigue property, leh corrosion resistance te pawh ngaihtuah a ni bawk. Hei hi welded structure-a hman tur bik (specific use requirements) angin thutlukna siam tur a ni.
1. Welding heat-a nghawng zone tiharh dan tur .
Welding heat-affected zone-a harsatna awm chu a bul berah chuan weld tur base material-a chemical composition leh cooling condition-ah a innghat a ni. A bulpui ber chu metal hrang hrangte metallographic structure property lantir nan a ni. Hardness test hi a awlsam zawk. Chuvangin, heat-affected zone hman tlanglawn (a tlangpuiin fusion zone-ah) a hardness hmax sang ber chu heat-affected zone performance tehna atan hman a ni. Heat-affected zone-a toughness, brittleness leh crack resistance te chu indirect takin a hrilhfiah theih a ni. Tun hnaiah Haz-a HMAX hi weldability tehna atana chhinchhiahna pawimawh takah ngaih a ni. Pawl khatah pawh harsatna hrang hrang a awm tih hriattir a ngai a ni. Hei hi base metal-a carbon awm zat, alloy composition leh cooling condition-te nen a inzawm tlat a ni. Chuvangin, quality nghet tak neih theih nan welding atana siamtu rintlak leh regular tak siam steel hman a tha.
2. Welding heat affected zone tihthianghlimna .
Welding heat-affected zone-a a innghahna chu welded joint-te cracking leh brittle failure thlentu ber a lo ni fo thin. Tuna kan siam chhuah data leh information te atanga a lan dan chuan embrittlement form te hi coarse crystal embrittlement, precipitation embrittlement, thermal strain aging embrittlement, hydrogen embrittlement, structure transition embrittlement, leh graphite embrittlement te an ni.
1) Crystal embrittlement coarse tak. Thermal cycling-in nghawng a neih avangin grain coarsening hi fusion line bulah a awm a, welded joint-a a lum lutukna hmun a awm bawk. Coarse grains hian base metal structure brittleness chu nasa takin a nghawng dawn a ni. A tlangpuiin grain size a lian chuan brittle transition temperature a sang zawk thin.
2) Precipitation leh embrittlement. Tar emaw tempering emaw a nih chuan supersaturated solid solution-ah hian carbide, nitride, intermetallic compound leh metastable intermediate dangte chu a lo chhuak ang. Heng phase thar lo chhuakte hian metal emaw alloy emaw chakna, khauh leh brittleness a tipung a ni. He thil thleng hi precipitation embrittlement an ti a.
3) Tissue embrittlement tih a ni. Haz welding-a brittle leh hard structure lo lang avanga embrittlement hi structure embrittlement an ti a. Carbon hniam tak, low-alloy high-strength steel hman tlanglawn tak tak tan chuan welded HAZ structure embrittlement hi MA component, upper bainite, leh coarse widmanstatten structure atanga lo chhuak a ni ber. Mahse carbon tamna steel (a tlangpuiin ≥0.2%) tan chuan structure embrittlement hi high-carbon martensite vang a ni ber.
4) Haz-a thermal strain aging embrittlement. Welding structure hi a siamnaah hian process a ngai a, chu chu material, shearing, cold forming, gas cutting, welding leh thermal processing dangte a ni. Heng processing avanga local strain leh plastic deformation te hian welded haz embrittlement ah hian nghawng nasa tak a nei a ni. Heng processing step te avanga embrittlement awm hi thermal strain aging embrittlement an ti a. Strain aging embrittlement hi static strain aging embrittlement leh dynamic strain aging embrittlement ah then theih a ni. A tlangpuiin 'blue brittleness' hi dynamic strain aging phenomenon a mi a ni.
3. Welding heat affected zone toughening .
Welding Haz hi non-uniform body a ni a, a structure leh a performance a ni. Fusion zone leh coarse-grained zone te hi a bik takin embrittlement an nei awlsam hle a, welded joint pumpui chak lohna hmunah an tel ve bawk. Chuvangin, welded haz toughness tihchangtlun a ngai a ni. Research atanga a lan dan chuan a hnuaia method pahnih hi HAZ toughen nan hman theih a ni.
1) Pawl thunun. Low-alloy steel hian carbon awm zat a control tur a ni a, chutiang chuan alloying element system chu alloying element tam tak low-carbon trace-te tihchakna system a ni. Chumi avang chuan welding-a cooling condition hnuaiah chuan haz chu dispersion-strengthened particles nen an insem darh a, low-carbon martensite, lower bainite leh acicular ferrite te chu a structure-ah toughness tha zawk nen an siam chhuak a ni. Pahnihnaah chuan, a theih ang anga grain boundary inthliarna chu control tur a ni.
2) Enkawlna khauh zawk. Structure pawimawh thenkhat chuan post-weld heat treatment hmangin joint performance tih that nan an hmang fo thin. Mahse, structure lian leh complex tak tak thenkhat chuan local heat treatment an hmang a, hei hi a tak taka hmannaah chuan a harsa zawk a ni. Chuvangin, welding heat input dik tak thlan dan te, welding process dik tak siam dan te, leh preheating leh post-heating temperature te siamrem dan te hi welding toughness tihchangtlunna atana hmanraw tangkai tak a ni.
Chu bakah, Haz-a toughness tihchangtlun dan dang a awm bawk. Entirnan, fine-grained steel chuan ferrite grains te chu a tithianghlim lehzual theih nan controlled process a hmang a, chu chuan material toughness a ti tha zawk bawk ang. Hei hi base metal ngeia element content-ah a innghat a, smelting technology nen a inzawm a ni.
Palinaah chuan welding heat-a nghawng zone chu a softening .
Welding hmaa cold work hardening emaw heat treatment emaw hmanga tihchak metal emaw alloy emaw tan chuan vector strength degree hrang hrang a awm tlangpui ang a, welding-in affected zone-ah hian a awm tlangpui ang. A tlangpui ber chu high-strength steels modulate tawh leh precipitation strengthening leh dispersion strengthening nei alloy te, welding hnua heat-affected zone-a softening emaw vector strength siam te hi a ni. Welding quenched leh tempered steel hian HAZ softening degree chu welding hmaa base material-a heat treatment state nen a inzawm a ni. Base metal weld hmaa quenching leh tempering treatment-a tempering temperature a hniam chuan a chakna a sang zawk chuan post-welding softening a na zawk ang. Practical research data tam tak chuan welding method hrang hrang leh welding wire power hrang hrang hman a nih chuan HAZ-a softening awmna hmun langsar ber chu A1-A3 inkar temperature hi a ni tih a tarlang.
