功能材料
功能材料
공능재료
JOURNAL OF FUNCTIONAL MATERIALS
2014年
z2期
76-80
,共5页
高纯钛%热变形%轴对称单向压缩%本构模型%微观组织
高純鈦%熱變形%軸對稱單嚮壓縮%本構模型%微觀組織
고순태%열변형%축대칭단향압축%본구모형%미관조직
high purity titanium%hot deformation%constitutive equation%microstructure%Zener-Hollomon
利用轴对称单向压缩法研究了纯钛在变形温度从723~873 K范围内、应变速率从0．001~1 s－1下的热压缩行为,并通过背散射电子衍射技术对不同热变形条件下的微观组织进行表征.研究结果表明,高温轴对称单向压缩下的纯钛经历从应变硬化阶段到稳态变形阶段的过程,在低的应变速率条件下材料流变应力出现平台,高的应变速率条件下,流变应力随变形过程逐渐增加.该合金流变应力的大小受变形温度、应变速率的强烈影响,随变形温度升高而降低,随应变速率提高而增大,高纯钛是一种具有正应变速率敏感性的材料.该合金高温流变应力σ可采用 Zener-Hollomon参数的函数来描述,函数表达式中参数A、α和n 的值分别为1．84×1024 s－1、0．013 MPa－1、12．66,其热变形激活能Q为415．69 kJ/mol.不同Z参数条件下微观组织对比分析表明在高的Z 参数条件下,材料未发生动态再结晶,在低的Z 参数条件下,材料发生明显的动态再结晶,在Z 值介于两者之间时材料发生部分再结晶.
利用軸對稱單嚮壓縮法研究瞭純鈦在變形溫度從723~873 K範圍內、應變速率從0．001~1 s－1下的熱壓縮行為,併通過揹散射電子衍射技術對不同熱變形條件下的微觀組織進行錶徵.研究結果錶明,高溫軸對稱單嚮壓縮下的純鈦經歷從應變硬化階段到穩態變形階段的過程,在低的應變速率條件下材料流變應力齣現平檯,高的應變速率條件下,流變應力隨變形過程逐漸增加.該閤金流變應力的大小受變形溫度、應變速率的彊烈影響,隨變形溫度升高而降低,隨應變速率提高而增大,高純鈦是一種具有正應變速率敏感性的材料.該閤金高溫流變應力σ可採用 Zener-Hollomon參數的函數來描述,函數錶達式中參數A、α和n 的值分彆為1．84×1024 s－1、0．013 MPa－1、12．66,其熱變形激活能Q為415．69 kJ/mol.不同Z參數條件下微觀組織對比分析錶明在高的Z 參數條件下,材料未髮生動態再結晶,在低的Z 參數條件下,材料髮生明顯的動態再結晶,在Z 值介于兩者之間時材料髮生部分再結晶.
이용축대칭단향압축법연구료순태재변형온도종723~873 K범위내、응변속솔종0．001~1 s－1하적열압축행위,병통과배산사전자연사기술대불동열변형조건하적미관조직진행표정.연구결과표명,고온축대칭단향압축하적순태경력종응변경화계단도은태변형계단적과정,재저적응변속솔조건하재료류변응력출현평태,고적응변속솔조건하,류변응력수변형과정축점증가.해합금류변응력적대소수변형온도、응변속솔적강렬영향,수변형온도승고이강저,수응변속솔제고이증대,고순태시일충구유정응변속솔민감성적재료.해합금고온류변응력σ가채용 Zener-Hollomon삼수적함수래묘술,함수표체식중삼수A、α화n 적치분별위1．84×1024 s－1、0．013 MPa－1、12．66,기열변형격활능Q위415．69 kJ/mol.불동Z삼수조건하미관조직대비분석표명재고적Z 삼수조건하,재료미발생동태재결정,재저적Z 삼수조건하,재료발생명현적동태재결정,재Z 치개우량자지간시재료발생부분재결정.
Isothermal compression tests of high purity titanium were performed on a Gleeble-1500 system in the temperature range between 723 and 873 K at strain rates between 0.001 and 1 s-1 .The flow behavior was de-scribed by a hyperbolic sine constitutive equation and the microstructures of samples were observed by electron back scattering diffraction (EBSD).The results show that during hot deformation pure titanium experienced from strain hardening to steady state deformation and the corresponding softening mechanism changes from dy-namic recovery to dynamic recrystallization;peak stress levels decreased with deformation temperature increas-ing and strain rate decreasing.High purity titanium was positive strain rate sensitive material.The flow stressσwas represented by the Zener-Hollomon parameter in an exponential equation withparameter A,αand n in ex-pression were 1.84×1024 s-1 ,0.013 MPa-1 and 12.66,with activation energy Q of 415.69 kJ/mol.The micro-structure of specimens with different Z values show that dynamic recrystallization was responsible for softening of low Z value sample,which dynamic recovery was the main reason for dynamic softening of high Z values sample,dynamic recrystallization occurred in the sample with middle Z value.Z value can be used to j ustified the dynamic softening mechanism for high purity Ti material.
