壓縮應變對沃斯回火球墨鑄鐵微結構及沖蝕行為之影響

Effects of Compressive Strain on Microstructure and Erosion Behavior of Austempered Ductile Iron

許正勳(C. H. Hsu) ； 劉洪才(H. C. Liu) ； 彭俊豪(C. H. Peng) ； 房瑛展(Y. C. Fang)

《鑄造工程學刊》 41卷4期 (2015/12) Pp. 1-8

摘要

沃斯回火球墨鑄鐵(ADI)基底微結構主要是由針狀肥粒體與殘留沃斯田體双相所組成，因此本研究使用MTS試驗機壓縮ADI，利用不同的壓縮應變量來探討ADI是否會發生麻田散體變態(Transformation induced plasticity, TRIP效應)，然後進一步觀察ADI壓縮試驗前後之金相組織，以及進行硬度及沖蝕試驗，以了解壓縮應變量對ADI微結構、硬度及沖蝕性質之影響。實驗結果顯示：ADI經正向壓縮應變時，其顯微組織之球墨周圍的沃斯田體相會因壓縮應變產生麻田散體變態，故推測會產生TRIP效應；當壓縮應變量達8%，會導致沃斯田體含量明顯地減少(32.6→22.7 vol.%)。隨著壓縮應變量的增加，可提高ADI的硬度，使得ADI之乾式與濕式耐沖蝕性質皆獲得改善。

關鍵字

沃斯回火球墨鑄鐵 ； 壓縮應變 ； TRIP效應 ； 硬度 ； 耐沖蝕

並列摘要

Austempered ductile iron (ADI) mainly consists of acicular ferrite and retained austenite dual-phases in its matrix. In this study, the ADI specimens were compressed by using MTS machine to obtain the different strains featuring martensite transformation (TRIP effect) on matrix. Before and after compressive tests, microstructural observation, hardness tests, and erosion tests were all carried out to show the effect of compressive strain on microstructure, hardness, and erosion behavior of ADI. Experimental results showed that in matrix austenite around nodule graphite transformed into martensite after normal compression. This confirmed the occurrence of the TRIP effect. When compressive strain increased up to 8%, austenite decreased from 32.6% to 22.7 vol.% in matrix. ADI raised the hardness by increasing the compressive strain. As a result, ADI enhanced the dry and wet erosion resistance.

並列關鍵字

Austempered ductile iron ； Compressive strain ； TRIP effect ； Hardness ； Erosion resistance