The Influence of Pulsed Arc and Electromagnetic Vibration on Microstructure and Properties of Super Stainless Steel Weld Metal

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基本資料

Project title

Code/計畫編號

NSC102-2221-E019-008-MY3

Translated Name/計畫中文名

脈衝電弧及電磁振動對超級不銹鋼銲道金屬微觀結構及性質之效應

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=3109414

Year

2013

Start date/計畫起

01-08-2013

Expected Completion/計畫迄

01-07-2014

Bugetid/研究經費

1417千元

ResearchField/研究領域

材料科技
機械工程

振動銲道金屬內的晶粒尺寸比直流銲道有晶粒細化的現象，低週疲勞下的振動銲道的反應應力值>直流銲道的反應應力值>原材的反應應力值。低週疲勞後的肥粒鐵相(α)的缺陷以wavy form的差排演化，而沃斯田鐵相(γ)基地則是以planar form的差排演化。另外，原材的疲勞在振幅1.2%應變，沃斯田鐵相誘發機械雙晶的出現。振動銲道與直流銲道中的肥粒鐵基地，於疲勞前呈現類似鳥類翅膀形態的差排組織，為許多差排環所堆疊而成。隨著低疲勞週次壽命增加，差排結構逐漸變的稠密，形成連續浪波狀形態，最終演變成典型差排包。用混合律預測複合相的硬度計算值與奈米壓痕硬度量測值比較，奈米壓痕數據結果近似於預測計算值。然而採用較大荷重下的Vickers量測值卻比預測公式計算值低，可能到受尺寸效應影響，因Vickers量測具有大的變形區域，其內含有多的晶界滑移及塑性變形。高解析微觀分析發現，振動銲道金屬內肥粒鐵相中的差排密度最大，其次是直流銲接的銲道金屬中肥粒鐵相，母材內肥粒鐵相中差排密度最為稀少。同時發現沃斯田鐵內部則幾乎無差排產生。經由FIB切出奈米壓痕區截面觀察到，母材肥粒鐵相在壓痕下之差排空乏區比銲道來的大，基於壓痕下差排間相互抵消形成差排空乏區，造成低的硬度測量值，故母材之肥粒鐵相硬度比銲道的肥粒鐵相低。簡言之，不銹鋼銲接後之機械性質轉變，是受於肥粒鐵相(α)的硬度值升高所支配。 Vibration welding can refine the grain size of weld metal, comparing to the DC weld metal. The response tensile stress of low cycle fatigue in vibration weld > DC weld >as-received metal at both strain amplitude. The dislocation evolution in the ferrite phase (α) evolves in the wavy form, while the austenite phase (γ) evolves in the planar form after low cycle fatigue. Dislocation evolution in austenite phase, no matter in as-received metal, DC weld metal or vibration weld metal, started from Persistant Luder Band (PLB). In addition, strain-induced mechanical twins appeared in austenite phase after fatigue under 1.2% strain amplitude. The flying birds wing-like dislocation structures, which were stacked from a number of dislocation loops, displayed in the ferrite matrix of DC weld and vibration weld metal before fatigue. The morphology of dislocaton structure changed to continuous wave-like, further cell structure from the initial wing-like form. Comparing to the nano-indentation measured hardness value, the predicted nanohardness of composite phase from rule of mixture, was close to the prediction. However, Vickers hardness under high load was much lower than the predicted value of composite phase. It might be caused by the size effect of large deformation zone with grain boundary sliding. Dislocation density in α phase of the vibration weld metal was the highest, that of the DC weld metal was next, and that of the base metal was the least. However, dislocations were not many in the γ phase. A cross-section of nano-indentation was obtained by FIB cutting process and examined under high resolution TEM. It was found that the dislocation free zone existed beneath the nanoindention in the α phase of base metal. The size of dislocation free zone in the α phase of base metal was larger than that of the two welded metals, could explain the lower nanoharness in the α phase of base metal. It was concluded that the higher nanohardness in the α phase of weld metal, especially in the vibration, was attributed to the existence of the highest dislocation density.

Keyword(s)

超級雙相鋼
脈衝電弧
電磁振動
相變態
孔蝕
Super duplex stainless stee
pulsed arc
electromagnetic vibrations
phase transformation
pitting

DSpace CRIS

The Influence of Pulsed Arc and Electromagnetic Vibration on Microstructure and Properties of Super Stainless Steel Weld Metal

基本資料

Description