| Summary: | 碩士 === 淡江大學 === 機械工程學系 === 86 ===
This study has been utilized cast welding technique to jojnt S45C hypoeutectoid steels and copper or SK3 hypereutectoid steels and copper to become compound casting. Take those compound casting into the air furnace to heat at 760℃ for two hours, then make continuous cooling transformation of water quench, oil quench, air cooling and furnace cooling. Otherwise, at 800℃ for two hours after making marquenching, martempering and austempering of heat treatment. Discussion have any effect on microstructure of S45C hypoeutectoid compound casting and SK3 hypereutectoid compound casting during before and after the above beat treatment:
1.Via heat treatment of microstructure of S45C / Cu compound casting: furnace cooling are coarse pearlite and precipitation oil quench are fine pearlite, martensite and precipitation ferrite; water quench are martensite and precipitation ferrite; marquenching are quenched martensite and retained austenite; martempering are mixed - structure of tempered martemsite with lower bainite and retained austenite; austempering are upper bainite and retained austenite.
2.SK3 /Cu compound casting have some microstructure by way of heat treatment for example: furnace cooling are nodular cementite dispersion in ferrite matrix; air cooling are medium pearlite and oversaturation carbon compound; oil quench are fine pearlite, martensite and ferrite; water quench are martensite and oversaturation carbon compound; marquenching are quesched martensite, carbide precipitation and retained austenite; martempering are mixed - structure of tempered martensite with lower bainite and retained austenite; austempering are upper bainite, retained austenite and carbide precipitateion.
3.After heat treatment, We will realize S45C / Cu and SK3 / Cu compound casting will have reaction layer to yield which divides into three parts;close to iron matrix is cast welding layer (Ⅰ) , nearby copper matrix is irregular layer (Ⅱ) , and between of them is medium layer (Ⅲ). Those layer thickness had no relationship with heat treatment because utilized EPMA analysis to know most Fe atom diffused into copper matrix, only a few Cu atom diffused into iron matrix and used X - ray analysis to know interface layer elements are Fe4Cu3 and CuFeO2. For same heat treatment to understand the shear force will rise along with carbon content but interface layer elements have not relationship with carbon content directly.
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