計畫編號：NSC89-2216-E032-007研究期間：199908~200007研究經費：365,000[[sponsorship]]行政院國家科學委員

林清彬

計畫編號：NSC89-2216-E032-007研究期間：199908~200007研究經費：365,000行政院國家科學委員

Tamkang University Institutional Repository

1行政院國家科學委員會補助專題研究成果報告顆粒型鋁基複合材料熔煉鑄造暨摩擦壓接研究計劃類別:þ個別計劃   o整合計劃計劃編號:NSC89-2216E-032-007執行期間:88年 8月 1日至 89年 7月 31日                計劃主持人: 林 清 彬                 執行單位:  淡江大學機械工程學系中   華   民   國  89年  9月  5日2顆粒型鋁基複合材料熔煉鑄造暨摩擦壓接研究The Effect of Heat Treatment on Tensile and Friction Welding Properties of ParticulateReinforced 7005 Al計畫編號: NSC89-2216-E-032-007執行期限: 8年8月1日至89年7月31日主持人:林清彬 淡江大學機械工程學系一、英文摘要The effect of heat treatment on tensileand friction welding properties of 7005Al/10wt% 15µm and 6µm SiC(p) compositesand 7005 Al/10wt% 15µm Al2O3(p)composites have been studied. If Al2O3particulate were used in the strengtheningphase, Al2O3 particulate had the same tensilestrength for the solution heat treatment andartificial heat treatment, which also washigher than the matrix. After frictionwelding, if the heat-effected zone hadstrengthening particulates, especially 6µmSiC particulate, it’s hardness and stressconcentration increased, and the weldingstrength decreased.Keywords: Particulate aluminum matrixcomposites; Friction welding;Heat effected zone; Weldingstrength二、緣由與目的Compared with the monolithicaluminum alloys, particulate aluminummatrix composites (PAMC) possess betterYoung’s modulus, hardness and wearresistance [1-4], which make it useful for thetransportation [5], electronic [6-7], andsporting goods [8] industries.Friction welding often used for joiningPAMC [9-10] is a solid-state weldingprocess, in which heat is generated byfriction from the relative motion of the partsto be welded. The application of an axialforce maintains intimate contact of the partsand causes plastic deformation of thematerial near the weld interface. Ellis et al.[11] showed that the joint strength of2618Al / 14%SiC particulate composites isabout 380N / mm2 with friction welding. Inaddition, if the work piece goes throughsolid solution, quenching and agingtreatments after friction welding, the jointstrength can rise to 431 N / mm2, which isclose to the previous 2618Al joint strengthof about 455 N / mm2.三 、 研究方法及結果與討論3.1研究方法3.1.1 Materials PreparationSiCp(βphase) and Al2O3p(α  phase)whose shapes are irregular are employed asthe reinforcements. This paper wasemployed to add 10wt% 15µm and 6µm SiCparticulate and 10wt% 15µm Al2O3particulate in 7005 aluminum alloyuniformly. After 7005Al is melted at 700℃,and then the molten slag were removed. The3added system and agitator were settled in aproper position in the crucible, the agitatorwas turned on and slowly sped up to 400rpm. Then, the upper impeller and the lowerimpeller were slowly sped up to 2000 rpmand 4000 rpm. After adding certain amountsof particulate, the impellers were turned off.The billets were put into a holding furnace at490 ℃ of a 350 ton indirect extrusionmachine and then using an extrusion rate of12 l/s, the billets were extruded into rods of18 mm in diameter.3.1.2 Friction WeldingThe welding work pieces were turnedand then put into a 200℃±3℃ air furnaceto anneal for two hours in order to eliminateresidual stress of turning. The welding pointsurface Ra was 2.5 µm before welding. Thework piece was fixed at a rotation speed of730 rpm, 3.4 N/mm2 ,  friction pressure and7secs friction timing were applied. Finally aforging pressure was used for 10 secondsafter friction process.　After the weldedflashes on the friction welded specimenswere machined, they were tensile testedusing an Instron machine with a crossheadspeed of 5mm/min at room temperature.3.1.3 Heat TreatmentTensile specimens were cut fromextruded 7005Al and the composites with agauge length of 60mm. The heat treatmentincluded ( I ) Holding at 400℃ for 90 minand then quenching in 22℃ water;( II )Holding at 400℃ for 90 min, quenching in22℃ water, and then a two-step artificialaging process was used, aging at 110℃ for8 hours, followed by 16 hours at 145℃, and,air cooling at 22℃ . After the weldedflashes were machined on the friction-welded specimens.3.1.4 Microstructure ObservationThen the microstructure was observedthrough an OPTIPHOT-100 Nikon opticalmicroscope.3. 2結果與討論      3.2.1 Particulate in matrix distributionThe distribution of strengtheningparticulate in 7005 aluminum alloy is shownin Fig.1, where we can see that SiC andAl2O3 particulate are well distributed in thematrix. In this paper, by using the process ofmolten casting, particulate of 15µm and 6µm were uniformly added to the matrixsuccessfully.3.2.2 The Effect of Heat Treatment onTensile PropertiesThe tensile properties of the specimen,which have been solution heat-treated areshown in Table 1. It was found that thetensile properties of 7005Al/15P/Al2O3composite were larger than 7005Al/6P/SiCand 7005Al/15P/SiC. The tensile propertiesof 7005Al/6P/SiC and 7005Al/15P/SiC werequite similar. Compared with the matrix, thecomposites possessed better tensile strength,and the elongation was reduced from 15%to10.3%. The tensile properties of thespecimens after artificial heat treatment areshown in Table 1. It was found that thetensile properties of 7005Al/6p/SiC and7005Al/15p/SiC were quite similar.3.2.3 The microstructure of the particulatein the heat affected zone    In Fig.2(a), we can see that there is anobvious plastic field in the Zpd zone of the7005Al.    Fig.2(b) is the 7005Al/15µm Al2O34particulate composites in the heat-affectedzone. The plastic flow is less obvious than in7005Al, because the Al2O3 particulate caneffectively prevent the plastic flow. We seethat in the Zpl zone, the Al2O3 particulate aredistributed evenly in the matrix, which isdifferent from the orientation of Al2O3particulate in the Zud zone.Fig.2(c) is the microstructure of7005Al/15µm SiC particulate composites inthe heat-affected zone. We can see that thereis more of an obvious plastic field in the Zpdzone than the 7005Al/15p/Al2O3. This isbecause when spinning was employed, thesofter matrix was ploughed by the SiCp, andmost of the heat was produced by friction of“the really contact point and then the flashtemperature of the SiCp transferred to thematrix. Heat formed per SiCp(q) is obtainedthrough the formula, q=τv=μdHv, (τ:shear per particulate, d : sliding distance, μ:coefficient of friction at constant spinningvelocity, sliding distance and plastic contactpressure ,and contact temperature 25℃–700℃ .For polycrystalline SiC is 0.4-1.1, forpolycrystalline Al2O3 is 0.5-1.0, Hv : averageVicker’s hardness, for polycrystalline SiC is3100, for polycrystalline Al2O3  is 2000. Theamount of friction heat is produced in theprocess of friction 7005Al/SiC compositeswere larger, the thermal conductivity ofSiC(0.06-0.1cal/cm.s. ℃ ) is larger thanAl2O3(0.06cal/cm.s.℃) ,and was helpful inproducing greater plastic flow in the matrix.Fig.2(d) is the microstructure of7005Al/6µm SiC particulate composites inthe heat-affected zone. We can see that thereis an obvious plastic field in the Zpd zone,because the 6µm SiC particulate movesmore easily than 15µm SiC and Al2O3particulate in the plastic flow.四 、 計畫成果自評The effects of heat treatment ontensile and friction welding properties ofextruded rods are discussed, and theconclusions are as follows:1.The solution heat treatment can achievelarger tensile strength in the composites thanthe parent material. For the 7005Al/SiC (p)composites, higher stress concentrationformed than in the 7005Al/Al2O3 (p)composite, so that a poorer tensile strengthis obtained; through the artificial heattreatment, precipitate formed easily at thematrix-particulate interface, higher stressconcentration was produced, and tensilestrength was poorer than in the parentmaterial. For the 7005Al/ Al2O3 (p) composite,the tensile strength obtained by the solutionheat treatment and the artificial agingtreatment were similar.2.The strengthening phase in the Zplincreased stress concentration and reducedit’s welding strength, and 7005Al/6p/SiChad the poorest welding properties. Breaksoccurred in the higher density of particulateof the Zpl zone, and 7005Al have dimpleductile fractures and the composite had lowductile fractures surface morphology.五、參考文獻[1] T. Mochida, M. Taya and D. J. Lloyd,Mater. Trans. Japan Inst. Metals 1991;32:931-942.[2] T. J. A. Doel and P. Bowen, Composites5Part A 1996; 27A:655-665.[3] A. L. Geiger and J. A. Walker, JOM1991; 43(8): 8-15.[4] B. Venkaraman and G. Sunderarajan,Acta Mater 1996;44(2):461-473.[5] Honda Motor Co. 1991. Brochure. Tokyo,Japan.[6] P. K. Rohatgi, F. M. Yarandi and Y. Liu,Materials Science and Engineering 1991;A147: L1-L6.[7] J. T. Lin, D. Bhattacharyya and C. Lane,Wear Proceedings of the 10thInternational Conference on Wear ofMaterials 1995: 883-888.[8] Alcan 1991 Product Brochure. SanDiego, CA.[9] K. K. Wang and P. Nagappan, WeldingJournal Research Supplement 1970;49(9): 419-425.[10] K. K. Wang and Wen. Lin, WeldingJournal Research Supplenment 1974;53(6): 233-241.[11] M. B. D. Ellis, M. E. Gittos and P. P. I.Threadgill, Materials World 1994;12(8): 415-417.Table 1 The tensile properties of particulate metalmatrix compositeSpecimen σy0.2%(Kgf/mm2)UTS(Kgf/mm2)σf(Kgf/mm2)ε1(%)7005Al29.6+28.1*35.17+34.5*35.3+34.0*14.0+15.0*7005Al/15P/SiC26.2+30.9*23.9+38.7*30.8+38.5*12.0+10.3*7005Al/6P/SiC26.5+30.9*33.1+38.6*31.18+37.4*11.1+10.9*7005Al/15P/Al2O331.9+31.8*39.8+39.7*38.7+38.4*14.3+11.0*+ : the artificial aging heat treated* : the solution heat treatedFig 1 Microstructure of (a)7005 Al base material;(b)7005 Al/15mm Al2O3; (c) 7005 Al/15mmSiC; (d) 7005 Al/6mm SiC particulatecomposites.Fig 2 Microstructure of (a) 7005 Al-7005 Al ;(b)7005 Al/15mm Al2O3(p)-7005 Al/15mmAl2O3(p) composites ; (c)7005 Al/15mmSiC(p)-7005 Al/15mm SiC(p) composites ;(d)7005 Al/6mm SiC(p)-7005 Al/6mm SiC(p)composites.

A Study on Fabrication and Friction Welding of Particulate Reinforced Aluminum Alloy

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