鎢含量及熱處理條件對多元合金白鑄鐵耐磨耗性之影響

Effects of W Content and Heat Treatment Conditions on Wear Resistance of Multi-component White Cast Irons

薛曉澤(H. T. Hsueh) ； 嚴建隆(C. L. Yen) ； 潘永寧(Y. N. Pan)

《鑄造工程學刊》 39卷3期 (2013/09) Pp. 13-26

摘要

本研究選用一基本之多元合金白鑄鐵：Fe-2.1%C-5%Cr-5%Mo-5%V-2%Co-X%W，探討不同W含量及熱處理參數（沃斯田化溫度、回火溫度及時間）對合金之顯微組織、硬度、耐沖蝕性及耐磨耗性之影響。研究結果顯示，A合金（2.1%C-5%W）及B合金（2.1%C-2%W）之鑄態顯微組織主要是由共晶碳化物MC、M2C及沃斯田鐵基地所組成，其中A合金之M2C碳化物較B合金多。合金經淬火及回火後，碳化物之形態、分佈及含量幾無變化，但基地組織在淬火後由沃斯田鐵變態為麻田散鐵，同時析出二次碳化物，回火後再由麻田散鐵變態為回火麻田散鐵。此外，基地中二次碳化物的含量會隨著回火溫度的升高而增加，而硬度則隨著回火溫度的升高首先升高，然後再降低；A合金在回火溫度525˚C時具有最高硬度，而B合金在回火溫度450˚C時具有最高硬度。又，A合金在回火溫度525˚C時具有最佳之耐沖蝕性，而在回火溫度450˚C時具有最佳之耐刮磨性。反觀B合金在回火溫度570˚C時具有最佳之耐沖蝕性及耐刮磨性。惟，合金硬度與耐沖蝕性及耐刮磨性並無一定相關性。另一方面，對於W含量之影響而言，低W含量之B合金其最佳回火態（570˚C）之耐沖蝕性及耐刮磨性均優於高W含量之A合金之最佳回火態（450˚C），此結果顯示W含量較低之多元合金白鑄鐵其耐磨耗性（沖蝕及刮磨）較佳，而所對應之最佳熱處理條件為：Austenitization 1100˚C-70min/Oil quench/Tempering 570˚C-2hr。

關鍵字

多元合金白鑄鐵 ； 熱處理 ； 沖蝕磨耗 ； 刮磨磨耗

並列摘要

In this study, a base alloy composition of Fe-2.1%C-5%Cr-5%Mo-5%V-2%Co-X%W was selected and the effect of W content (2% and 5%), together with the influence of heat treatment conditions (austenitization temperature, tempering temperature and time), on the microstructure and wear resistance property were evaluated. The as-cast microstructures of both alloy A (2.1%C-5%W) and alloy B (2.1%C-2%W) contain eutectic carbides of MC and M2C in an austenitic matrix. The eutectic carbides remain unchanged during the subsequent austenitization, quenching and tempering treatments, except that secondary carbides in M3C form were precipitated in the matrix. On the other hand, the as-cast austenitic matrix was transformed to martensite after quenching, which in turn was transformed to tempered martensite after tempering. The macro-hardnesses of both alloys increase first, reach a peak, then decreases as the tempering temperature increases, with the peak hardness occurring at 525˚C for alloy A and 450˚C for alloy B. Regarding the erosion wear resistance, alloy A exhibits the best resistance at the tempering temperature of 525˚C, while 570˚C for alloy B. On the other hand, the best abrasion wear resistance took place at 450˚C for alloy A and 570˚C for alloy B. The results indicate that no clear correlation between alloy hardness and wear resistance property was obtained. In addition, alloy B (2%W) exhibits better wear resistance property (both erosion and abrasion) than alloy A (5%W) in the tempered state, indicating that a reduced W content can achieve an increased resistance to both erosive and abrasive wear. And, the corresponding optimal heat treatment conditions are: Austenitization 1100˚C-70min/Oil quench/Tempering 570˚C-2hr.

並列關鍵字

Multi-component white cast iron ； Heat treatment ； Erosion wear ； Abrasion wear