475不銹鋼顯微結構分析

The Studies of the Microstructures of the Costom 475 Stainless Steel

余承軒(Cheng-Hsuan Yu)

指導教授 ： 趙志燁

國立屏東科技大學/工學院/機械工程系所/碩士(2008年)

https://doi.org/10.6346/NPUST.2008.00213

摘要

合金經970℃和1050℃固溶1小時後，其顯微結構為板狀α及殘留沃斯田鐵，溫度越高殘留沃斯田鐵含量越多，此板狀α(或稱麻田散鐵，c/a≒1)結構為體心立方結構(B.C.C.)，其晶格常數為a=0.289nm，而殘留沃斯田鐵結構為面心立方結構(F.C.C.)，晶格常數a=0.360nm。於-80℃/8H深冷處理後，將固溶時之殘留沃斯田鐵完全轉變為板狀α結構，此時之晶格常數為a=0.289nm。
經時效(450℃、550℃及650℃)處理，在450℃時可發現α相及沃斯田鐵相之產生，其α相之晶格常數為a=0.289nm。而在550℃和650℃時可發現L12 (Ni3Al)結構之析出物於基地內整合析出，此時之結構為板狀α與沃斯田鐵，並且有L12(面心立方結構)之析出物，其晶格常數為a=0.375nm。並且可以觀察出時效溫度550℃提高至650℃時，其Ni3Al之析出物由微粒狀轉變為顆粒狀，沃斯田鐵含量大量增加。與其他學者比較，固溶溫度提高至980-1050℃後，其B2相(NiAl)之析出物並未被發現。

關鍵字

顯微結構 ； 板狀α ； 沃斯田鐵 ； 晶格常數

並列摘要

Being solution heat treatment(SHT) on 970℃/1H or 1050/1H, and quenching room-temperature the microstructure of the alloy is the α phase and retained austenite. The higher SHT temperature would posses the higher retained austenite. This plate-α(called matensite)belong to the body-centered cubic(B.C.C.) structure with the lattice parameter a=0.289nm. The retained austenite belongs the face-centered cubic(F.C.C.) structure with lattice parameter a=0.360nm. After -80℃/8H subzero heat treatment. The retained austenite would transform into plate-α.
During the 450℃ aging processes, the α-plate martensite would be decompose to α + austenite phase, increasing the aging temperature to 550-650℃.The L12-phase(Ni3Al) particles would be found within the matrix . The lattice parameter of the L12-phase is a=0.375nm. Compared with the other workers studies , increasing the SHT temperature to 980-1050℃, the precipitation of the B2-phase(NiAl) will be inhibited.

並列關鍵字

Microstructure ； α phase ； Austenite ； Subzero treatment

參考文獻

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