表面深滚处理对AZ91镁合金组织及性能的影响（英文）
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摘要
在室温下对固溶处理后的AZ91镁合金块体材料进行表面深滚处理,以研究其对合金表面显微组织和力学性能的影响。分析被加工试样表层沿深度方向的显微硬度和显微组织。结果表明,表面影响层厚度达到2.0 mm,可分为3个亚层:从最表面起约为400mm厚的严重变形层,大约600mm厚的中等变形层和厚度达1000mm的小变形层。在变形层中除晶粒细化外,还观察到应变诱导析出的β相(Mg_(17)Al_(12)),尤其是在严重变形层和中等变形层内。研究认为,晶粒细化、应变硬化和沉淀强化的协同作用使AZ91镁合金在表面深滚后的硬度显著提高。
A solution-treated AZ91 bulk material was deep-surface-rolled at room temperature to investigate the effect of deep surface rolling on the microstructure and mechanical properties of the alloy. Microhardness and microstructure along the depth of the treated surface layer were characterized. The results show that the affected layer was up to 2.0 mm thick and consisted of three sublayers: a severe deformation layer with thickness of about 400 mm from the topmost surface, a medium deformation layer with thickness of around 600 mm and a small deformation layer up to 1000 mm thick. In addition to grain refinement in the deformation layer, strain-induced precipitation of β phase(Mg_(17)Al_(12)) was observed, particularly in the severe and medium deformation layers. It is believed that the cooperative effects of grain refinement, strain hardening and precipitation strengthening led to the significant increase in hardness of the AZ91 alloy after the deep surface rolling.
A solution-treated AZ91 bulk material was deep-surface-rolled at room temperature to investigate the effect of deep surface rolling on the microstructure and mechanical properties of the alloy. Microhardness and microstructure along the depth of the treated surface layer were characterized. The results show that the affected layer was up to 2.0 mm thick and consisted of three sublayers: a severe deformation layer with thickness of about 400 mm from the topmost surface, a medium deformation layer with thickness of around 600 mm and a small deformation layer up to 1000 mm thick. In addition to grain refinement in the deformation layer, strain-induced precipitation of β phase(Mg_(17)Al_(12)) was observed, particularly in the severe and medium deformation layers. It is believed that the cooperative effects of grain refinement, strain hardening and precipitation strengthening led to the significant increase in hardness of the AZ91 alloy after the deep surface rolling.
引文
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[23] HOU Li-feng, WEI Ying-hui, LIU Bao-sheng, XU Bing-she. High energy impact techniques application for surface grain refinement in AZ91D magnesium alloy[J]. Journal of Materials Science, 2008, 43:4658-4665.
[24] SALAHSHOOR M, GUO Y B. Process Mechanics in Deep Rolling of Magnesium-Calcium(Mg Ca)Biomaterial[C]//ASME 2011International Manufacturing Science and Engineering Conference.Corvallis, USA, 2011:303-311.
[25] ZHUANG H, CHEN M, CARTER E A. Elastic and thermodynamic properties of complex Mg-Al intermetallic compounds via orbital-free density functional theory[J]. Physical Review Applied,2016, 5:064021.
[2] LIU X C, ZHANG H W, LU K. Strain-induced ultrahard and ultrastable nanolaminated structure in nickel[J]. Science, 2013, 342:337-340.
[3] ZHANG Le-hao, ZOU Yun, WANG Hong-tao, MENG Liang, LIU Jian-bin, ZHANG Zhong-wu. Surface nanocrystallization of Mg-3wt.%Li-6wt.%Al alloy by surface mechanical attrition treatment[J]. Materials Characterization, 2016, 120:124-128.
[4] LI W L, TAO N R, LU K. Fabrication of a gradient nano-microstructured surface layer on bulk copper by means of a surface mechanical grinding treatment[J]. Scripta Materialia, 2008, 59:546-549.
[5] WU X, TAO N, HONG Y, XU B, LU J, LU K. Microstructure and evolution of mechanically-induced ultrafine grain in surface layer of Al-alloy subjected to USSP[J]. Acta Materialia, 2002, 50:2075-2084.
[6] LIU G, WANG S C, LOU X F, LU J, LU K. Low carbon steel with nanostructured surface layer induced by high-energy shot peening[J].Scripta Materialia, 2001, 44:1791-1795.
[7] CHENG Ming-long, ZHANG De-yuan, CHEN Hua-wei, QIN Wei,LI Jin-sheng. Surface nanocrystallization and its effect on fatigue performance of high-strength materials treated by ultrasonic rolling process[J]. The International Journal of Advanced Manufacturing Technology, 2016, 83:123-131.
[8] LOU S, LI Y, ZHOU L, NIE X, HE G, LI Y, HE W. Surface nanocrystallization of metallic alloys with different stacking fault energy induced by laser shock processing[J]. Materials&Design,2016, 104:320-326.
[9] KIRAN G V, KRISHNA K H, SAMEER S, BHARGAVI M,KUMAR B S, RAO G M, NAIDUBABU Y, DUMPALA R, SUNIL B R. Machining characteristics of fine grained AZ91 Mg alloy processed by friction stir processing[J]. Transactions of Nonferrous Metals Society of China, 2017, 27:804-811.
[10] SUN H Q, SHI Y N, ZHANG M X, LU K. Plastic strain-induced grain refinement in the nanometer scale in a Mg alloy[J]. Acta Materialia, 2007, 55:975-982.
[11] HOU Li-feng, WEI Ying-hui, LIU Bao-sheng, XU Bing-she.Microstructure evolution of AZ91D induced by high energy shot peening[J]. Transactions of Nonferrous Metals Society of China,2008, 18:1053-1057.
[12] LALEH M, KARGAR F. Effect of surface nanocrystallization on the microstructural and corrosion characteristics of AZ91D magnesium alloy[J]. Journal of Alloys and Compounds, 2011, 509:9150-9156.
[13] ALTENBERGER I. Deep rolling-The past, the present and the future[C]//Proceedings of the 9th International Conference on Shot Peening. Paris, France, 2005:144-155.
[14] ZHUANG W Z, HALFORD G R. Investigation of residual stress relaxation under cyclic loading[J]. International Journal of Fatigue,2001, 23(S):s31-s37.
[15] ZHUANG W, LIU Q, DJUGUM R, SHARP P K, PARADOWSKA A.Deep surface rolling for fatigue life enhancement of laser clad aircraft aluminium alloy[J]. Applied Surface Science, 2014, 320:558-562.
[16] NIKITIN I, ALTENBERGER I, MAIER H J, SCHOLTES B.Mechanical and thermal stability of mechanically induced near-surface nanostructures[J]. Materials Science and Engineering A,2005, 403:318-327.
[17] JUIJERM P, ALTENBERGER I. Fatigue performance enhancement of steels using mechanical surface treatments[J]. Journal of Metals,Materials and Minerals, 2007, 17:59-65.
[18] ALTENBERGER I, WAGNER L, MHAEDE M, JUIJERM P,NOSTER U. Effect of deep rolling on the cyclic performance of magnesium and aluminum alloys in the temperature range 20-250oC[C]//10th International Conference on Shot Peening. Tokyo, Japan,2008:557-562.
[19] ZHUANG W, WICKS B. Multipass low-plasticity burnishing induced residual stresses:Three-dimensional elastic-plastic finite element modeling[J]. Proceedings of the Institution of Mechanical Engineers:Part C, 2004, 218(6):663-668.
[20] LUO Jun, ZHU Hang-tian, LIANG Jing-kui. Determination of crystallite size and strain by X-ray powder[J]. Physics, 2009, 38(4):267-275.(in Chinese)
[21] MEYER D, BRINKSMEIER E, HOFFMANN F. Surface hardening by cryogenic deep rolling[J]. Procedia Engineering, 2011, 19:258-263.
[22] MEYER D. Cryogenic deep rolling–An energy based approach for enhanced cold surface hardening[J]. CIRP Annals-Manufacturing Technology, 2012, 61:543-546.
[23] HOU Li-feng, WEI Ying-hui, LIU Bao-sheng, XU Bing-she. High energy impact techniques application for surface grain refinement in AZ91D magnesium alloy[J]. Journal of Materials Science, 2008, 43:4658-4665.
[24] SALAHSHOOR M, GUO Y B. Process Mechanics in Deep Rolling of Magnesium-Calcium(Mg Ca)Biomaterial[C]//ASME 2011International Manufacturing Science and Engineering Conference.Corvallis, USA, 2011:303-311.
[25] ZHUANG H, CHEN M, CARTER E A. Elastic and thermodynamic properties of complex Mg-Al intermetallic compounds via orbital-free density functional theory[J]. Physical Review Applied,2016, 5:064021.