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|標題:||52 & 82 鎳基填料對鎳基超合金熱龜裂敏感性研究|
The Study of Hot Cracking Susceptibility during Welding on Ni-based Superalloy with 52&82 Ni-base Filler Metal
|摘要:||本研究利用鎢極惰性氣體遮護電弧銲接法(Gas Tungsten Arc Weld, GTAW)的方式將鎳基填料(Inconel 52 & Inconel 82)添加至鎳基超合金(Incoloy 800H & Incoloy825)，期望在高溫下增強鎳超基合金之抗熱龜裂性之特性。爾後使用點銲式可調應變試驗(Spot Varestraint Test)評估銲接性，觀察鎳基超合金在高溫之下外加應變產生裂紋之狀態，並探討組成元素對熱龜裂敏感性的高低。
結果顯示銲接完畢之後皆為沃斯田鐵組織且並無裂紋產生，鎳基填料合金之固液溫差值為 800H-82>800H-52>825-52>825-82。點銲式可調應變試驗之後，鎳基填料合金銲接熱龜裂敏感性高到低為 800H-52>825-52>800H-82>825-82，固液溫差值的範圍大小與熱龜裂敏感性較無直接相關。中心區產生的裂紋較無規則性，未外加應變的銲道區域ε=0%並沒有產生裂紋 52 鎳基填料銲道區域呈現柱狀晶組織，，82 鎳基填料銲道區域呈現等軸枝狀晶組織，Incoloy 800H 基材系列合金晶粒組織方向性較高，Incoloy 825 基材系列合金晶粒組織方向性較一致。外加應變ε=5%的銲道區域有產生裂紋，裂紋均延著兩晶粒組織方向差較大的高角度晶界產生，並發現 82 鎳基填料銲道裂紋周遭有富含 Nb 元素組織回填，52 鎳基填料並沒有。
外加應變區裂紋的晶界取相差皆大於 30o，殘留應變皆大於 0.2。Incoloy 825 基材填料合金，未發生裂紋的晶界角度 30o 以下數量增多；82 鎳基填料合金，裂紋所需的殘留應變從 1 降低至 0.2。|
In this study,metal matrix composites are using Gas Tungsten Arc Weld to combine nickel-base filler which is Inconel 52 and Inconel 82 with nickel-based superalloy which is Incoloy 800H and Incoloy 825.Expectly,Nickel-basd superalloy has resisting hot cracking susceptibility at high temperatures.It is observed crack which happened in nickel-base superalloys under strain and high temperatures by using Spot Varestraint Test to assess weldability and discuss compose which element affect hot cracking susceptibility. These results indicate that all of metal matrix composites has no hot crack and Austenite sturcture after welding. The difference of Solidus of slow cooling and Liquidius of slow cooling( △ T) is 800H-52> 825-52> 800H-82>825-82. After using Spot Varestraint Test, the order of crack total length is 800H-52> 825-52> 800H-82>825-82. The crack total length has no directly relationship with △T.The crack is irregularly in Center Zone. It has no crack under 0% strain in metal matrix composites weld. The subgrain structure was celler in 800H-52 and 825-52 weld, but was dominantly equiaxed dendritic in 800H-82 and 825-82. Furthermore,the subgrain structure's directionality in 800H-52 and 800H-82 was higher than 825-52 and 825-82.It has amount of crack under 5% strain in metal matrix composites weld.Crack was happened between grain and grain which has more different grain directionally along high grain boundary angle. The tip of crack and other zone had congregated with niobium under applying 5% strain in 82 nickel-base filler alloy's weld but not in 52 nickel-base filler alloy's weld. All of Crack was happened with misoriention above degree of 30 and residual strain above 0.2 under 5% strain zone.Grain boundary angle has numerous under degree of 30 in the same series of 82 nickel-based filler alloys.Residual strain has to require from 1 lower to 0.2 in series of 825 nickel-basd superalloy alloys.
|Appears in Collections:||土木工程學系所|
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