高錳合金化延性鑄鐵之沃斯回火製程與性質研究

Study on Austempering Processes and Properties of High Manganese Alloyed Ductile Iron

呂宗耀(Tsung-Yao Lu)

指導教授 ： 許正勳

大同大學/工程學院/材料工程學系所/碩士(2009年)

摘要

本研究主要目的是針對添加1wt%的錳元素與工業上常用之FCD450(0.25wt% Mn)兩種延性鑄鐵，執行不同條件(300℃-3hr、360℃-2hr)沃斯回火熱處理使成為沃斯回火延性鑄鐵材料(ADI)，然後進一步探討與比較鑄態與ADI之顯微結構、機械性質及化學腐蝕性質的差異，以了解高錳合金化之相關效應。
實驗結果顯示機械性質方面，添加1.0wt%的錳元素延性鑄鐵因波來鐵的含量更多可有效的增加抗拉強度、硬度、耐沖蝕及耐磨耗性等；然而，在化學腐蝕性質方面，無論是極化試驗(3.5wt% NaCl)、浸漬試驗(2N H2SO4、2N HCl)，對鑄態而言，1.0wt% Mn高錳延性鑄鐵比FCD450之耐腐蝕性不佳。對ADI而言，雖然高錳含量ADI之耐蝕性仍較差，但同時可以發現ADI之耐蝕性皆比鑄態為優，其中360℃-2hrs之ADI因殘留沃斯田鐵含量較多，故其耐腐蝕性質表現亦較佳。

關鍵字

錳元素 ； 球墨鑄鐵 ； 沃斯回火 ； 機械性質 ； 腐蝕性質

並列摘要

In this study, two kinds of ductile iron (DI), 1wt% Mn alloyed ductile iron and unalloyed ductile iron (FCD450), were selected as experimental materials. Both the austempering conditions consisting of 300℃-3hrs and 360℃-2hrs were respectively adopted to further treat these irons as austempered ductile iron (ADI). Then microstructural observation, mechanical tests (such as hardness, tensile, impact toughness, and KIC), and corrosion tests (such as polarization in 3.5 wt% NaCl, immersion tests in 2N H2SO4 and 2N HCl) were all performed to understand the correlation of microstructure, mechanical and corrosion behaviors of these iron..
The experimental results showed that the addition 1wt% Mn could increase the pearlite content in microstructure, resulting in an increase of mechanical properties such as hardness, tensile strength, erosion resistance, and wear resistance regardless of DI and ADI; however, decrease the ductility, impact toughness, and KIC value. In corrosion behavior, DI and ADI with 1 wt% addition seem to have worse corrosion resistance as compared to un alloyed ones. It also noted that ADI is superior to DI in corrosion resistance due to the occurrence of retained austenite in its microstructure.

並列關鍵字

Manganese ； Nodular graphite cast iron ； Austempering

參考文獻

1. M.L. Chen, “Study on Austempering Processes and Applied Characteristics of Cobalt and Nickel Alloyed Ductile Irons ” ,TTU of thesis for doctor of science, 2009, pp.11-21

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8. J.F. Janowak and R.B.Gundlach, “Approaching Austempered Ductile Iron Properties by Controlled Cooling in the Foundry”, Heat Treating”, Vol.14, 1985, pp.25-31.

9. ASTM A644-92, “Standard Terminology Relating to Iron Castings”, Annual Book of ASTM Standards, 1999, pp.341-342.

10. B.J. Weng, S.T. Chang, H.N. Liu, and S.E. Hsu, “Crack Initiation and Propagation of Austempered Ductile Iron and Its Properties”, Chinese Journal of Materials Science”, vol.23, 1991, pp.278-286.