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標題: | 雙金屬水泥鎚頭之鑄造製程開發及其耐磨耗性 Casting Process Development of the Bimetal Hammer and Its Abrasive Wear Resistance Property |
作者: | Pi-Chun Yu 游弼鈞 |
指導教授: | 潘永寧(Yung-Ning Pan) |
關鍵字: | 雙金屬,雙液澆鑄,高鉻鑄鐵,耐磨耗性,熱處理, Bimetal,High Cr cast iron,Heat treatment,Wear resistance, |
出版年 : | 2007 |
學位: | 碩士 |
摘要: | 本研究針對雙金屬(高鉻鑄鐵—合金鋼)水泥鎚頭鑄件,建立其鑄造技術,並探討最佳熱處理條件及分析鎚頭之顯微組織(包含具耐磨耗性之頭部、具韌性之柄部及二者之界面區)及機械性質(包含硬度、衝擊值及耐磨耗性)。在實驗方法上,探討不同Destabilization溫度及回火溫度對於高鉻鑄鐵及合金鋼之顯微組織、硬度值、衝擊值及耐磨耗性之影響,以建立雙金屬水泥鎚頭之最佳熱處理條件,並以SEM及EDAX觀察碳化物之形態及分析雙金屬界面之組成。本研究之目的在於獲致優良硬度及耐磨耗性之高鉻鑄鐵頭部及優良韌性之合金鋼柄部,以期在實際應用時可獲致較傳統單合金高錳鋼鎚頭較長的使用壽命。
本研究採用底澆法將二種合金熔液連續澆注入鑄模內,在澆注完第一種合金熔液但並未完全凝固之前,即接續澆注第二種合金熔液,以得到雙金屬水泥鎚頭。針對熱處理製程而言,本研究所獲致之最佳熱處理條件為(900 ~ 1000)°C/2hr/強風冷卻/500°C/2hr。鎚頭柄部採用鎳鉻合金鋼,其鑄態顯微組織為麻田散鐵針狀組織,經熱處理後變態為回火麻田散鐵,而鎚頭頭部則採用高鉻白口鑄鐵,其鑄態顯微組織包含M7C3碳化物及沃斯田鐵,經熱處理後沃斯田鐵變態為回火麻田散鐵,並會析出細粒二次碳化物。柄部合金鋼與頭部高鉻鑄鐵兩者之界面接合良好,並無空孔或氧化物生成,且在部份區域有二相混合之情形。另,由磨耗試驗與衝擊試驗結果顯示,本研究所開發之雙金屬鎚頭具有良好之耐磨耗頭部與耐衝擊柄部,可取代傳統單合金高錳鋼水泥鎚頭。 This study intended to develop the casting method for the production of bimetal hammers which consist of Cr-Ni steel shank and high Cr cast iron head, to establish the optimal heat treatment conditions for achieving the desired microstructures, hardness and wear resistant property, and to analyze the characterizations of carbides precipitated and the interface between the aforementioned two alloys by using SEM and EDAX. The aim of this study is to attain a bimetal hammer which has a tough alloyed steel shank and a high wear resistant head, which can replace the traditional single alloy (high Mn steel) hammer with substantially increased service life. A double-pour technique was employed to cast the bimetal hammer. A bottom-pour gating system with an overflow located at the intended interface between two alloys, together with a top open riser have been designed for this particular casting. Also, the optimal heat treatment conditions have been found to be (900~1000)°C/2hr/ FAC/500°C/2hr. The as-cast microstructures of the hammer head consist of proeutectic austenite dendrites and eutectic phases of M7C3 carbide and austenite. After heat treatment, most of the austenite transformed to martensite after quenching, which subsquently transformed to temper martensite after tempering. In addition, numerous small secondary carbides, which have been identified as M7C3, can also be observed within the original austenite domain. The as-cast microstructure of the hammer shank is martensite, which transformed to temper martensite after heat treatment. Furthermore, the analyses of the interface region reveal that not only a sound fusion between two alloys was achieved, but also little porosity and oxides were observed. The developed bimetal hammer exhibits good combined properties of a tough shank, 21 J/cm2, and a hard head, over 50HRC, which has much better wear resistance than the traditional high Mn steel hammer. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/30899 |
全文授權: | 有償授權 |
顯示於系所單位: | 機械工程學系 |
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