循環塑變對雙相鋼及其銲接件低週次疲勞與微觀組織研究
Other Title
A Study of Microstructure and Fatigue Property of Cyclic Plastic Deformation in Duplex Stainless Steel and Its Weldment
Journal
材料科學與工程
Journal Volume
37
Journal Issue
2
Start Page
110
End Page
115
ISSN
0379-6906
Date Issued
2005-06
Author(s)
Abstract
不同鉻鉬含量之雙相鋼SAF 2205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SAF2205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。低應變週期疲勞後之微觀組織顯示有許多雙晶生成，且差排多為PLB差排組織；高應變振幅則有麻田散鐵的出現且差排多為錯位差排胞組織。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.
Subjects
雙相不銹鋼
低週疲勞
應變比
銲接
差排
Duplex Stainless Steels
LCF
strain ratio
Weld
dislocation
Type
journal article