[[alternative]]Effect of Residual Stress Release on the Thermal Fatigue of Hardfacing Deposite S420 Martensite stainless steel

碩士工業教育與技術學系[[abstract]]本研究目的在研究不同消除殘留應力製程對麻田散體不□鋼銲補之殘留應力與對熱疲勞影響。實驗中，銲接方法採用潛弧銲接法；母材採用S400低碳鋼，填充金屬採用S420型麻田散體型不□鋼；應力消除製程變數包括平行加熱、振動應力釋放、低溫應力釋放與珠擊；銲件不同位置之銲接熱循環與熱疲勞加熱－冷卻循環將被記錄以分析熱疲勞之熱應力作用；殘留應力量測採用ASTM標準E837之鑽孔應變計方法；裂縫觀察使用金相顯微鏡，而相變化溫度利用熱膨脹儀來分析。實驗結果顯示：在相同銲接條件下，平行加熱銲接、振動應力釋放、低溫應力釋放與珠擊四種不同銲接製程對於殘留應力都有釋放的作用；壓縮殘留應力能延遲熱疲勞裂縫的形成，且如低溫應力釋放與珠擊，於熱疲勞初期對於裂縫的成長有抑制的作用。而於熱疲勞中期，低溫應力釋放與珠擊之裂縫成長速率與一般銲接組比較有接近的趨勢，其原因可能與殘留應力釋放有關；比較一般銲接與平行加熱銲接之冶金影響，肥粒體不一定有利於阻止裂縫的成長；銲道外側容易長成大裂縫，其原因可能是銲道外側易生成柱狀晶；銲道外側與中心中間與銲道中心之裂縫分佈情況有接近的趨勢；熱疲勞過程裂縫形成及成長方向皆無規則性。abe This paper aimed at the investigation of the effect of stress relief processes on residual stress and thermal fatigue in hardfacing by martensite stainless steel. In this study, the base metal of type S400 steel and the filler metal of type S420 stainless steel were used. A submerged arc welding was utilized. The stress relief processes include parallel heat welding, vibration stress relief, shot peening, and controlled low temperature stress relief. The thermal cycle of different location in weldment were recorded during welding and thermal fatigue processes for analysis of thermal stress. The residual stresses were determined by using the hole-drilling strain-gage method of ASTM standard E837. The phase transformation temperature was determined by using the dilatometer. The experimental results showed that all of stress relief processes in this study there are having lower residual stresses than the as-welded sample. The compressive residual stress in surface layer of sample can retard the initiation of cracking due to thermal fatigue. Because of the stress relief in thermal fatigue process, the different magnitude of residual stress from various test samples there are similar crack growth rate. The ferrite in martensite matrix is not sure good effect for retarding the crack propagation. Generally, the larger cracking is easy found at the outside of weld, this is because that it is having a cellular structure. Based on the observation of experiment, both of the crack initiation and propagation there are not habit directions.tc 摘要 ........................................................................................Ⅰ 目次 ........................................................................................ IV 圖次 ........................................................................................VIII 表次 ........................................................................................ⅩII 頁次 第一章 緒 論...........................................................................1 1.1 研究背景與動機 ..........................................................1 1.2 研究目的........................................................................1 1.3 研究問題與研究假定 ..................................................2 1.4 名詞解釋.........................................................................4 第二章 文獻探討....................................................................7 2.1 銲接殘留應力形成………...........................................7 2.1.1 平面收縮對殘留應力的影響....................................7 2.1.2 淬火效應對殘留應力的影響..................................10 2.1.3 相變化對殘留應力之影響.......................................11 2.2 銲接殘留應力釋放方式.............................................15 2.2.1平行加熱銲接..............................................................15 2.2.2低溫應力釋放..............................................................15 2.2.3振動應力釋放..............................................................18 2.2.4珠擊法...........................................................................19 2.3 麻田散體不□鋼...........................................................19 2.3.1麻田散體不□鋼相變化.............................................21 2.3.2麻田散體不□鋼之銲接冶金.....................................21 2.3.3銲後熱處理...................................................................24 2.4疲勞斷裂過程分析.........................................................26 2.5金屬熱疲勞與影響因素分析........................................27 2.5.1熱疲勞發生的機構分析..............................................27 2.5.2平均應力對熱疲勞壽命的影響.................................30 2.5.3裂縫形成及成長與冶金結構的關係.........................30 2.5.4影響熱疲勞裂縫形成的因素......................................34 2.5.5 影響熱疲勞裂縫擴展速率因素分析.........................36 2.5.6熱疲勞裂縫成長方向分析...........................................36 第三章 實驗步驟...................................................................38 3.1 實驗流程圖...................................................................38 3.2 實驗試片.......................................................................39 3.3預熱(層間)溫度實驗....................................................39 3.4 銲接實驗.......................................................................39 3.5 平行加熱實驗..............................................................43 3.6 銲接熱循環量測..........................................................43 3.7 熱膨脹儀實驗..............................................................47 3.8 銲後熱處理實驗..........................................................47 3.9 拉伸實驗.......................................................................47 3.10低溫應力釋放實驗.....................................................50 3.11振動應力釋放實驗.....................................................50 3.12 珠擊實驗.....................................................................50 3.13 殘留應力量測............................................................54 3.14熱疲勞試驗.................................................................54 3.15熱疲勞裂縫觀察與量 測 ..........................................57 3.16金相分析......................................................................57 3.17金相組織比例判定....................................................61 第四章 結果與討論..............................................................62 4.1 相同銲接條件下不同製程殘留應力分析...............62 4.2 熱疲勞過程熱應力分析.............................................70 4.3 各個製程之熱疲勞裂縫分析...................................73 4.4 熱疲勞過程殘留應力分析........................................81 4.5 熱疲勞過程裂縫分析..................................................83 4.5.1裂縫成長過程分析....................................................83 4.5.2.裂縫分佈情形分析...................................................88 第五章 結論與建議............................................................102 5.1 結論 .............................................................................102 5.2 建議..............................................................................10