塑性變形對17-4PH不鏽鋼析出動力之影響

Effect of plastic deformation on the precipitation kinetic of 17-4PH Stainless steel

羅友誌(Yu-Chih Lo)

指導教授 ： 李勝隆

國立中央大學/工學院/機械工程學系/碩士(2014年)

摘要

本研究藉由微結構觀察、X光繞射分析、微差掃描熱分析及機械性質測試（硬度、拉伸），探討不同冷加工量（20%、40%、60%）對17-4PH不鏽鋼析出動力之影響。結果顯示，商用板材之17-4PH不鏽鋼經固溶淬火後其基地為麻田散鐵，然隨著冷加工量的增加此麻田散鐵基地並無顯著的變化，但由X光繞射分析可發現因擇優取向的關係，繞射峰（CuFe/Fe4Cu3與殘留沃斯田鐵相（γ））隨冷加工量的增加有越之明顯的情況，但在X光漫射效應加強下，於60%冷加工量時，反而迅速消失；另由微差掃描熱分析可發現，冷加工可有效降低合金強化富銅相的析出溫度，其中又以含有60%冷加工量之17-4PH不鏽鋼有最佳之析出動力，且由機械性質測試可發現，未經冷加工之17-4PH不鏽鋼於450℃進行人工時效2小時可達頂時效，而冷加工則可有效增加17-4PH不鏽鋼之機械性質（硬度、抗拉強度），其中含60%冷加工量之17-4PH不鏽鋼於400℃進行人工時效4小時可獲得最佳之機械性質（硬度、抗拉強度）且硬度顯著增加約27%，由此可知，冷加工可有效提升17-4PH不鏽鋼之析出動力，進而能有效提升機械性質。

關鍵字

17-4PH不鏽鋼 ； 塑性變形 ； 析出動力

並列摘要

In this study, 17-4PH stainless steel changes as different percentage of cold working had been measured. The results of microstructure observing, XRD analysis, DSC analysis, and mechanical properties measuring was collected. From these facts, the commercial 17-4PH stainless steel after solid solution quenching becomes martensitic and does not have obvious changing between different amounts of cold work. In XRD analysis, the signal strength of CuFe/Fe4Cu3 and the remain austenite increase as the cold work percentage increase due to the preferred orientation, but the strength rapidly decrease as the cold work percentage reached 60% due to the larger scattering effect for X-ray diffraction. We also found that cold work can reduce the precipitation temperature of Copper rich phase, the most cold work percentage (60%) has the best precipitation kinetic. Form the results of mechanical properties measurements, 17-4PH stainless steel doing 2 hours aging at 450℃ can reach to peak-aged. Cold work can increase mechanical properties of 17-4PH stainless steel. While 60% cold work followed 400℃ aging for 4 hour could make the best properties (hardness increase 27%).

並列關鍵字

17-4PH stainless steel ； Plastic deformation ； Precipitate kinetic

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