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研究生:陳昭仁
研究生(外文):Chen, Jau-Ren
論文名稱:鑄鐵之雷射相變硬化處理及硬化層之特性研究
論文名稱(外文):Study of Laser Surface Transformation Hardening on Cast Iron and the Characteristics of Hardened Layers
指導教授:敖仲寧敖仲寧引用關係
指導教授(外文):Aoh Jong-Ning
學位類別:碩士
校院名稱:國立中正大學
系所名稱:機械工程學系
學門:工程學門
學類:機械工程學類
論文種類:學術論文
論文出版年:1997
畢業學年度:85
語文別:中文
論文頁數:84
中文關鍵詞:雷射相變硬化鑄鐵滑動磨耗
外文關鍵詞:laser transformation hardeningcast ironsliding wear
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本文在於探討雷射參數組合與FCMP 60鑄鐵之相變硬化層特性之間的關係
,雷射參數為雷射功率、掃瞄速度與離焦量的組合而硬化層特性包含硬化
層內的硬度分佈、硬化層的幾何特徵(硬化層深度與寬度)以及雷射表面
處理後的表面粗糙度,硬化深度與雷射功率大致成正比關係增加、而隨著
掃瞄速度與雷射光束直徑增加而減少。在表面沒有熔融的情況下,硬化層
主要是由片狀麻田散鐵(plate martensite)所構成的,而在表面有熔融的
情況下,會形成由白鑄鐵及粒滴斑鐵(ledeburite)組成的很淺之熔融層
。在多道次硬化方面,在上一道與下一道的重疊部份會有回火軟化的現象
,其顯微組織為回火麻田散鐵。除此之外,本文亦探討石墨對於鑄鐵在雷
射相變硬化處理的影響。在本研究中,對母材與硬化層在不同的磨耗負荷
下施以滑動磨耗,實驗結果顯示硬化層的耐磨耗性相較於母材而言有明顯
的改善,尤其是在重磨耗負荷之下,其耐磨耗性的改善更加明顯。不管是
母材或硬化層,其磨耗機制皆因磨耗負荷不同而不同,對母材磨耗而言,
若其磨耗速率較快,則其磨耗機制主要為切削(cutting)與犁田(
ploughing)等研磨磨耗。因為硬化層的硬度高到足以提供有效的耐磨耗性
來抵抗嚴重的研磨磨耗以致在硬化層產生的磨耗速率明顯較低。

In this work, the relationship between laser processing
parameters including laser power, scanning speed and laser beam
diameter (defocus), and the characteristics of hardened layer of
FCMP 60 cast iron including hardness distribution of the
hardened layer, geometrical features (the width and depth of
hardened layer) and surface roughness after laser treatment was
investigated. There was a general tendency that the hardened
depth increased as the laser power increased. The hardened depth
also increased withdecreasing scanning speed and laser beam
diameter. The microstructure of hardened layer mainly consisted
of plate martensite if no surface melting occurred. With surface
melting, the surface region consisted of eutectic ledeburite
(white iron) and the molten region was very shallow comparing to
the whole hardened layer. In multi-track hardening, there was
tempering effect occurred in the overlapped region between the
previous track and the next track. This led to hardness
reduction as a result of formation of tempered martensite. In
addition, the influence of graphite flakes in laser
transformation hardening on cast iron was also discussed in this
work.Sliding wear test was carried out on both base metal and
hardened layer under different wear loads. The wear resistance
of hardened layer was significantly improved after laser
treatment in comparison with base metal, especially under
extreme wear load. The wear mechanism varied with the wear load
both on base metal and hardened layer. Under higher wear rate of
base metal, the cutting and ploughing wear were the dominant the
wear mechanism. The higher hardness and microstructure of
hardened layer provided an effective wear resistance against
severe abrasive wear. Lower wear rate after sliding wear test
was expected accordingly.

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