Character of Low Cycle Fatigue and High Strain Rate Deformation for Fe Based Stainless Steel Welds (II)

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簡歷

基本資料

Project title

Code/計畫編號

NSC92-2216-E019-010

Translated Name/計畫中文名

鐵基不銹鋼之機械與抗蝕性應用研究---子計畫IV：鐵基不銹鋼銲件之低週期疲勞及高應變速率變形特性健會(II)

Project Coordinator/計畫主持人

Shing-Hoa Wang

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Mechanical and Mechatronic Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=828383

Year

2003

Start date/計畫起

01-08-2003

Expected Completion/計畫迄

01-07-2004

Bugetid/研究經費

772千元

ResearchField/研究領域

材料科技

不同鉻鉬含量之雙相鋼 SAF 2205 及 SAF 2507 素材及銲件在不同應變速率及應變振幅環境下，原素材及氣護鎢極電弧銲（TIG）銲件之疲勞特性結果顯示，兩種雙相鋼初期呈現迅速硬化而後為一穩定循環軟化現象，疲勞壽命 SAF 2205 優於 SAF 2507，銲接後疲勞強度均降低，平均應力變化現象在低應變振幅較為明顯。雙相鋼銲接件主裂縫出現於母材區，且裂紋以肥粒鐵相間之沿晶傳播路徑為主。疲勞後之微觀組織顯示許多雙晶生成且差排多為 PLB 差排組織。高鎳鉬之超級沃斯田鐵不銹鋼 254 SMO 素材，在不同應變速率，其拉伸應變速率越快延展性越好；相反破裂疲勞應變速率越快壽命越短，其斷口面疲勞條紋越為明顯。The strain amplitude and strain ratio effect upon low cycle fatigue have been investigated in two kinds of duplex stainless steels. Their weldments at all strain level exhibits appreciable hardening during the first few cycles, followed by softening with continued cycling. The fatigue life of SAF 2205 duplex stainless steel is superior to that of SAF 2507 duplex stainless steel. The GTAW welds exhibit poor fatigue strength and life as compared to the received metal. The fatigue strength of duplex stainless steel is sensitive to mean stress change at low strain amplitudes. The main fatigue crack of the weldments occurs at the base metal. The crack path propagates along the interphase boundaries, although most of cracks are initiated at the ferrite boundaries. The microstructure of fatigued specimen consists of twins, PLB dislocation structure, dislocation cluster and vein structure. The tensile properties of super austenitic stainless steel 254 SMO show an abnormal behavior. It exhibits a better strength and ductility as the strain rate increases. Conversely the fatigue life reduces as increasing strain rate.

Keyword(s)

雙相不銹鋼
低週疲勞
應變比
銲接
差排
Duplex Stainless Steels
LCF
strain ratio
Weld
dislocation

DSpace CRIS

Character of Low Cycle Fatigue and High Strain Rate Deformation for Fe Based Stainless Steel Welds (II)

基本資料

Description