Cryogenetic Strength and Toughness of Duplex Stainless Steel after Grain Refining and Phase Transformation by Thermal Cycling

瀏覽統計 Email 通知 RSS Feed

簡歷

基本資料

Project title

Code/計畫編號

MOST106-2221-E019-026-MY2

Translated Name/計畫中文名

熱循環處理後晶粒細化與相變態的雙相不銹鋼低溫強度與韌性

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=12388144

Year

2018

Start date/計畫起

01-08-2018

Expected Completion/計畫迄

01-07-2019

Bugetid/研究經費

1230千元

ResearchField/研究領域

材料科技

"天然液化氣體的輸送管及貯存容器，液態氫氣/液態氮氣/液態氫氣的貯存容器，及深海低溫環境的耐腐蝕鋼材，一般均已添加高鎳的鋼材為主，且低溫適用的合金結構材料被選擇的鋼種類不多。利用自行設計製作的多頻次熱循環處理設備，用於歐洲瑞典Sandvik 公司開發的超級雙相不銹鋼SAF2507，初期結果已明顯呈現，晶粒細化的效果。晶粒尺寸由原材的17 μm 可細化至6 μm。本研究探討超級雙相不銹鋼，在不增加鎳含量下，經多頻次熱循環後，晶粒細化的機制，晶粒結晶方位的變化，各相之間晶界角度改變，析出物扮演的角色，殘留沃斯田鐵中變形誘發雙晶的可行性等，以上因素均牽涉到特殊雙相不銹鋼的低溫機械特性的改良，達到必須符合低溫結構材料規範，降服比（降服強度/最大抗拉強度）需低於85％的準則，高的低溫衝擊韌性能，以及更低的延脆性轉換溫度（DBTT）。本研究將以2 年的時間完成，第1 年：利用自行設計組裝的多頻次熱循環系統，進行試片製作，及上述的各項微觀組織，相變態及結晶學的分析。第2 年：接續前第一年研究外，實施各項低溫環境的拉伸實驗，與低溫衝擊韌性量測。比較相同熱處理時間下，不同熱循環模式下，（如連續多頻次熱循環，尖峰/凹谷持溫多頻次熱循環，與恆溫熱處理），各低溫機械性質差異與不同微觀組織組成的關聯性。期盼本計畫2 年後，將商用特殊不鏽鋼的創新改良，使具有優越的低溫韌性及超低的延脆性轉換溫度，成功的可應用於低溫壓力容器，低溫輸送管件，或低溫結構組件。" "High nickel content steels are generally apply to natural liquefied gas pipes and storage containers, liquid hydrogen/liquid nitrogen/liquid hydrogen storage containers, and deep-sea low-temperature environment of corrosion-resistant steel. But, the grades of alloy steels for low temperature applicaton are not many. The self-designed thermal cycle processing equipment was used in SAF2507 duplex stainless steel. The preliminary results have shown the effect of grain refinement obviously. The grain size can be refined from 17 μm to 6 μm. The mechanism of grain refinement, the change of crystal grain orientation, the angle of grain boundaries between two phases, the role of the precipitates, and the strain induced twin in retained austainite etc. all affect the improvement of low temperature strength and toughness in super duplex stainless steels by thermal cycling. The criteria of low temperature strenth and toughness for structural material are the yield ratio (yield strength/ultimate tensile strength) demanded lower than 85%, high low-temperature impact energy, and lower ductile brittle transition temperature (DBTT). This study will be completed in 2 years. The first year, complete all diferent parameter test specimens production by self-designed thermal cycling system for the above-mentioned microstructure, phase transformation and crystallographic analysis. The second Year: conduct the tensile testing below the zero temperature environment, and low-temperature impact toughness measurement. The relationship and the mechanism will be clarified between the low temperature mechanical properties and the different types of thermal cycles (such as continuous thermal cycling, thermal cycling with holding time at peak/valley and isothermal heat treatment) under the same heat treatment time. It is expected that after two years of the project, the innovation of commercial special stainless steel will be modified. So that it has excellent low temperature toughness and ultra low ductile-brittle transition temperature, which can be successfully applied to cryogenic pressure vessels, cryogenic conveying pipes or low temperature structural components"

Keyword(s)

晶粒細化
低溫強度與韌性
多頻次熱循環
相變態
grain refinement
low temperature strength and toughness
thermal cycling
phase transformation

DSpace CRIS

Cryogenetic Strength and Toughness of Duplex Stainless Steel after Grain Refining and Phase Transformation by Thermal Cycling

基本資料

Description