การศึกษาอิทธิพลของแบบหล่อที่มีผลต่อคุณสมบัติทางกลและโครงสร้างจุลภาคของเหล็กหล่อสีเทา (FC25)

Abstract

The objective of the engineering project is to study the effects of the mold materials on the mechanical properties and the microstructures of the Gray cast iron ( FC 25 ), three types of mold arc used, Cast steel sc 46 , CO2 mold and Shell mold . The molds havecy lindrical shape with height of 215 mm., the in-sides top diameter of 96 mm.,and the in-sides bottom diameter of 60 mm.From the experimental results we found the highest heat conduction rate occurring in the Cast steel sc 46 mold. Result in the hardness around the outer periphery of the workpiece with Short and Thin graphite and Fine Pearlite. The average hardness measured on the workpiece surface of the cast steel sc 46 , co. mold ,and the shell mold are 346.61 HV , 212.48 HV , and 220.12 HV respccclivcly. The tensile strengths measured on the workpiece of the cast steel SC 46,CO? mold ,and the shell mold are 38.2575 Kgt7mm,24.9664 Kgf7mm,and 23.5689 Kgf/mm respccclivcly .The microstructure of the Gray Cast Iron FC 25 from the Cast steel mold consists ol iron carbide (Fc^ C) around the outer periphery and of type D and E graphite with size ol 7.8 ASTM and fine pearlite around the center .The microstructure of the cast iron from the co, mold consists of type B and D graphites with sizes of 5-6 ASTM and fine pearlite around the outer periphery and of types A and B graphites with sizes of 3-5 ASTM around the center. The microstructure of the cast iron from the Shell mold consists of type B and D graphites with size of 4-5 ASTM around the outer periphery and of types A and B graphites with little amount of type c graphite and consists pearlite al the center.