FB2馬氏體耐熱鋼中Laves相在焊接過程中演化行為的研究FB2馬氏體耐熱鋼中Laves相在焊接過程中演化行為的研究EVOLUTION BEHAVIOR OF LAVES PHASE IN FB2 STEEL DURING WELDING 采用熱模擬的方法研究了 FB2 鋼(一種新型 9%Cr 馬氏體耐熱鋼)中 Laves 相在焊接熱循環(huán)中的演化行為. 首先借助 SEM 發(fā)現(xiàn)了存在于原始供貨狀態(tài)下的 FB2 鋼中尺寸在微米級別的 Laves 相顆粒; 進一步的分析表明, 這些 Laves 相的出現(xiàn)是由鑄造過程中的枝晶偏析導致的. 焊接熱模擬實驗結(jié)果表明, 在加熱過程中, Laves 相與基體γ -Fe 發(fā)生共晶反應導致的組分液化會給 FB2 鋼熱影響區(qū)帶來熱裂傾向; 在冷卻后的樣品中發(fā)現(xiàn)了一些網(wǎng)狀的共晶組織, 利用 SEM 的 EDS 和 TEM 分別得到了該共晶組織的成分信息和結(jié)構(gòu)信息, 確定該共晶組織的 2 個組分為χ 相和γ -Fe. 在此基礎之上, 較為詳細地分析了不同峰值溫度熱模擬后樣品中共晶組織的形成過程, 解釋了共晶組織不同形貌的產(chǎn)生原因. Elevating steam parameters are the main key to enhance the efficiency of fossil power plants, to reduce fuel consumption and noxious emission. Therefore, a lot of new creep resistant martensitic stainless steels have been developed, among which FB2 steel (a new 9%Cr martensitic stainless steel) is the most promising candidate for manufacturing steam turbine rotors operated at temperature range from 600 ℃ to 650 ℃. In the present work, the evolution behavior of Laves phase in the as received FB2 steel was studied by thermal simulation technique. Firstly, some sparse micron-sized particles of Laves phase were observed in as received FB2 steel by SEM. It was concluded that the large Laves phase particles formed in casting due to dendritic segregation. Then constitutional liquation resulting from eutectic reaction between Laves phase and γ -Fe in the heating process of welding thermal simulation was found, suggesting a liquation crack tendency in heat affected zone of FB2 steel. In the specimens experiencing thermal simulation, some eutectic microstructures were observed by SEM. Based on the results of EDS analysis and SAED, the two eutectic constituents were identified as χ phase and γ-Fe. At last, the reason for the difference in morphology of eutectic microstructures between specimens experiencing thermal simulation with different peak temperatures was analyzed. 全文下載：https://pan.baidu.com/s/1kVKeG4Z
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