The Phase Transformation and Mechanical Properties of Mo Bearing Special Stainless Steels for New Ultra-Supercritical Coal-Fired Power Plant after Multiple Thermal Cycling

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Project title

Code/計畫編號

MOST105-2221-E019-011

Translated Name/計畫中文名

含鉬特殊不銹鋼於新超臨界電廠經多週次熱循環後的相變態及機械特性

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=11882453

Year

2016

Start date/計畫起

01-08-2016

Expected Completion/計畫迄

01-07-2017

Bugetid/研究經費

1271千元

ResearchField/研究領域

材料科技

"歐洲瑞典Sandvik 公司開發出的超級雙相不鏽鋼SAF2507 及超級高鉬奧斯田254SMO 不鏽鋼，已被應用於新一代新的超超臨界燃煤機組（例如台電林口發電廠），石化業、和汽電共生動力廠，等設備所用之新結構材料。一般電廠使用壽命設計為30 年，結構材料長期歷經千萬週次的連續加熱/冷卻，累計熱循環運轉，將會促使結構材料退化，甚至破裂，引起公安事故，造成人員傷亡及財產損失。本研究採以多頻次的熱循環處理，探討抑制高溫硬脆相生成之可行性與相關機械特性，進而探討殘留沃斯田鐵相，含量變化與低溫環境下的機械特性。本研究將以3 年的時間完成，第1 年：自行設計組裝，多週次熱循環系統加溫/冷卻系統，由測試到正常運作，至少需半年時間。系統測試成功後，開始不同上下溫度限及溫度範圍下，進行多週次熱循環實驗與相變態分析。第2 年：接續前第一年不同上下溫度限及溫度範圍的熱循環實驗與相變態分析，配合第一年實驗參數設定上限溫度的相等同熱週次時間持溫。比較相同熱處理時間下，多週次熱循環相變態與相同上限溫度的恆溫相變態差異性。抑制硬脆σ相形成之可行性，與其相關機械特性。第3 年：配合前兩年實施的不同熱循環模式，探討殘留沃斯田鐵量變化，與低溫環境下機械特性優劣關係。期盼本計畫3 年後，可解決長期受高溫硬脆相生成，造成結構破裂之困擾，更給予特殊不鏽鋼的創新改良，具有優越的低溫延性及韌性，可應用於低溫壓力容器，提昇超級不鏽鋼的應用溫度範圍與保固。" "It is well known that the super duplex stainless steel SAF2507 and high Mo content of super austenitic 254SMO developed by Europe Sweden Sandvik are new structural materials applied widely for using in the ultra-supercritical coal-fired units (such as Taipower Linkou Power Plant), petrochemical industry, and cogeneration power plants, and other equipment. Generally, the design life of power plant is about 30 years. The accumulated thousands heat/cooling cycles through continuous operation for a long-term, the structural materials would cause degradation and even rupture, resulting in the public safety, casualties and property damages. The purposes of this study explore the feasibility of inhibiting high temperature brittle phase formation in adopting multi thermal cycling process, and investigate the content of retained austenite associated with low temperature mechanical properties. This project will be completed within three years. The goal of first year: A multi-heating/cooling thermal cycle system will be self-designed and assembled to normal operation required at least six months. After the system test is successful, the thermal cycle experiments and phase transformation analysis implement with different upper and lower temperature limits and temperature range. The goal of second year: Besides continue the work of first year, an isothermal heat treatment will conduct under the equal time of equivalent thermal cycles at the same upper temperature in comparison the difference between the thermal cycling and isothermal in order to inhibit the formation of brittle σ phase and its related mechanical properties. The goal of third year focuses on the low temperature mechanical properties associated with the amount of retained austenite generated from both thermal cycling process and isothermal process in previous two years. It is expected that this three-year project can solve the problem of brittle phase formation causing structure failure and explore the excellent low-temperature ductility and toughness for the special stainless steels in advanced application."

Keyword(s)

超級不鏽鋼
硬脆相
殘留沃思田鐵
相變態
Super duplex stainless steel
hard brittle phase
retained austenite
phase transformation

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The Phase Transformation and Mechanical Properties of Mo Bearing Special Stainless Steels for New Ultra-Supercritical Coal-Fired Power Plant after Multiple Thermal Cycling

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