Cov qauv Widmansite ntawm titanium alloy yog tus cwj pwm los ntawm kev sib txuas txuas txuas mus ntxiv rau ntawm thaj tsam ntawm cov qoob loo ntawm cov thawj coarse nplej, flaky bundle domains faib nyob rau hauv cov nplej, thiab lamellar ntawm flaky Mutually.
Txij li cov theem thiab hauv Widmanstatten cov qauv tswj hwm kev sib raug zoo ntawm crystallographic theem, cov qauv muaj lub siab tawv "kwv yees", thiab nws yog qhov nyuaj los txhim kho nws cov qauv los ntawm kev kho cua sov thiab kev kho cua sov nyob rau hauv cov xwm txheej uas tsis yog quenching. Kev hloov pauv hauv titanium alloy yog txheej txheem ntawm nucleation thiab nucleus loj hlob. Thaum qhov tshwj xeeb ntim qhov sib txawv ntawm ob lub allotropes loj, cov nyhuv ntim yuav tshwm sim thaum lub sij hawm hloov pauv txheej txheem thiab kev ntxhov siab sab hauv yuav raug tsim, tsim Dislocations los yog qhov chaw ua haujlwm txhawb nqa recrystallization, uas ua rau muaj kev hloov pauv hauv cov qauv-daim ntawv thiab txawm tias luv luv thiab spheroidization. . Cov kws tshawb fawb tau txhim kho cov qauv Widmanstatten los ntawm cheeb tsam quenching thiab + zone cyclic kho cua sov.
Cov khoom siv xeem yog Φ280mm TC4 disc muab los ntawm ib lub koom haum tshawb fawb. Theem transformation point yog ntsuas los ntawm metallographic txoj kev ua (985 ± 5) degree, thiab cov qauv coj mus rau tag nrho cov nyob rau 1/2 ntawm lub circumference ntawm lub disk. Txhawm rau kom tau txais cov qauv Widmanstatten xav tau rau qhov kev xeem, cov qauv tau txais yog thawj annealed nyob rau hauv cheeb tsam (1020 degree × 1h, AC), ces tus qauv raug quenched nyob rau hauv cheeb tsam (1020 degree × 30min, WQ), thiab ces nyob rau hauv thaj tsam Hauv cheeb tsam +, 960 degree × 10min thiab 750 degree × 10min tau cycled ib zaug, 3 zaug, 5 zaug, 7 zaug thiab 9 zaug raws li. Tom qab lub voj voog, tag nrho cov qauv tau muab ob npaug rau annealed (940 degree × 30min, AC+700 degree × 4h, AC), thiab qhov ntsuas tensile tau ua tom qab ob npaug ntawm annealing; Lub tensile tawg tau pom thiab tshuaj xyuas siv GSM6460 scanning electron microscope. Tom qab cov qauv metallographic tau etched nrog HF + HNO3+H2O (ntim piv 1: 2: 5) etching tov, lub microstructure tau pom nyob rau hauv OLYMPUSPMG3 optical microscope.
Cov txiaj ntsig tshawb fawb:
(1) Thaum lub sij hawm cyclic kev kho cua sov nyob rau hauv thaj tsam ntawm 960 degree × 10min thiab 750 degree × 10min, raws li tus naj npawb ntawm cov voj voog nce, lub zog ntawm TC4 alloy maj mam txo thiab cov plasticity nce. Tom qab 9 lub voj voog, thaj chaw shrinkage nce ntau.
(2) Raws li tus naj npawb ntawm thermal cycles nce, qhov sib piv ntawm cov sawb maj mam txo, thiab ib nrab spheroidization tshwm sim. Tom qab 9 lub voj voog, theem nrab flaky theem precipitated nyob rau hauv lub flaky matrix. Nyob rau hauv tib lub voj voog, tom qab muab ob npaug rau annealing, lub strip yog obviously coarsened thiab cov qauv yog ruaj khov dua.
(3) SEM kev soj ntsuam thiab kev soj ntsuam ntawm qhov chaw nres nkoj tensile qhia tau hais tias daim ntawv tawg ntawm lub tensile fracture hloov ntawm cleavage fracture ua ntej cycling → cleavage + dimple fracture → dimple fracture.
