• 作者： 周釋善; 李世欽; 林鴻榮; 傅兆章
• 作者服務機構： 國立成功大學冶金及材料工程系; 國立成功大學礦冶研究所; 工業技術研究院金屬工業研究所
• 中文摘要： 鋼鐵材料發生回火脆性後雖可在高於600℃以上之溫度加熱急冷而消失，但再將之停滯於
  500℃左右時還是會再生脆化。
  本實驗是應用熱機處理，對脆化後的鋼材於350℃做各種不同程度加工後，於500℃做不
  同時間的再回火，藉此形成亞晶粒（substructure），一方面提高材料?性，另方面希望藉此打散
  偏析元素，使其脆性除去。
  500℃是低合金鋼容易產生回火脆化的溫度，此溫度停滯時間愈久，脆性愈增加。本實驗結
  果顯示500℃恒溫回火脆化後的鋼材，於350℃加工500℃再回火，隨著再回火時間的增長
  不但脆性不會增加，相反地?性增加，30％加工度者即使於爐中放置47小時亦無再脆化現象發
  生，不僅改善回火脆性，而且抑制脆性再發生。各種熱機處理方法均使降伏強度及抗拉強度大幅
  增加。
• 英文摘要： Temper embrittlement is one of the seriousproblems in steels. It has been established thattemper embrittlement is induced by impurityelements such as P, Sn, Sb, As and so forthunder the infulence of alloy elements Ni, Cr,Mn, etc. Though the temper embrittlement may beremoved by heating above 600℃ and rapidcooling, yet if the materials heated or cooledagain slowly through the temperature about500℃, the embrittlement will be induced again. In this study, the steel was embrittled at500℃ for one week. The embrittled materialwas forged at 350℃ by various forging ratiothen retempered at 500℃ for various times, soas to form substructure in order to improve thetoughness, and to remove by diffusion such de-fects of structure as dislocation and the segre-gated impurty elements, as a resuet the defectsof the brittleness may be removed. The temperature near 500℃ is the embrit-tlement range of low alloy steels. The longerthe staying time the more embrittlement is in-duced. In this study when the steel forged at350℃ then retempered at 500℃ after embrittle-ment treatment, the retempering time increases,but the embrittlement doesn't increase, opposi-tely the toughness increases. For 30% forgingratio, even when the retempering time increasesto 47 hrs, the toughness will increase still more.All methods of thermomechanical treatment usedin this study increase both yield strength andtensile strength. For the same retemperingtime, low forging ratio material has highertoughness than high forging ratio material.
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