超塑预处理对Al-Zn-Mg-Cu铝合金显微组织及力学性能的影响

通过力学性能测试、扫描电镜和透射电镜观察,研究了传统处理工艺（conventional treatment,CT）和超塑预处理（superplastic pre-treatment,SPPT）对Al-Zn-Mg-Cu铝合金组织和性能的影响。结果表明,采用超塑预处理使铝合金晶粒细化到11μm、而传统工艺处理后的晶粒尺寸为30μm;超塑预处理使Al-Zn-Mg-Cu铝合金抗拉强度提高3．5％,塑性提高25.7％．通过透射电镜观察发现：经超塑顶处理后时效析出相细小、弥散,晶界析出相（grain boundary precipitares,GBP）较小、晶界无析出带（precipitates free zone,PFZ）电较窄．这种组织特性可使合金得到较好的力学性能。     

时效时间对冷轧2024铝合金组织和力学性能的影响

通过拉伸力学性能及硬度测试和透射电子显微镜（TEM）观察,研究了室温条件下30%变形量冷轧2024铝合金180 ℃时效不同时间的力学性能和组织。结果表明,冷轧态2024铝合金在180 ℃时效时,出现了双峰时效强化。时效120 min时,合金中含有大量位错墙,有大量S’相析出,出现第一个强化峰,合金抗拉强度为560 MPa,伸长率为3.6%;时效720 min时,合金中S’相完全溶解,有Ω相析出,且位错含量降低,出现第二个强化峰,此时合金抗拉强度（563 MPa）与第一个峰值时几乎相等,但伸长率达9%,较120 min时提升150%。     

焊接工艺对2024铝合金接头组织与性能的影响

研究了分别采用熔化极氩弧焊(MIG)和钨极氩孤焊(TIG)进行2024铝合金焊接的工艺,并对在两种工艺条件下获得的接头的力学性能和微观组织结构进行测试分析.试验结果表明,MIG焊接头的抗拉强度达到母材抗拉强度的60%以上,而TIG焊接头的抗扭强度只达到母材抗拉强度的50%,这是由于MIG焊接头焊缝组织要比TIG焊接头焊缝组织细小,晶界处共晶相数量明显减少,晶内析出了很多细小的共晶相,有利于提高接头强度;且MIG焊的热输入比TIG焊的热输入小,MIG接头软化程度也比TIG焊要小.因此在试验条件下,MIG焊工艺获得接头的性能要优于TIG焊接头.     

大冷变形对2024铝合金组织和性能的影响

通过力学性能检测、扫描电镜和透射电镜观察,研究了3种工艺下大冷变形对2024铝合金组织和性能的影响。结果表明,大冷变形后2024铝合金的伸长率随时效时间的延长呈台阶式变化,当时效时间≤40min时,δ5≥8％;时效时间≥160min时,伸长率急剧降低,δ5约为2％。研究表明,伴随S′相析出所产生的晶界无析出带及粗大的晶界平衡相,是2024铝合金伸长率急剧降低的主要原因。     

预拉伸处理对2024铝合金组织和性能影响

采用硬度测试、室温力学性能测试、组织观测,研究了自然时效前的预拉伸(预拉伸率1%、1.5%,2%、2.5%、3%)对2024铝合金时效过程和拉伸性能影响。结果表明,预拉伸处理延缓了合金的自然时效过程,但提高了合金的硬度和强度。当预拉伸率为2%时,合金的最高强度和伸长率分别为456 N/mm2,20.6%,这是由于冷变形量不同、回复所引起的软化、GPB区和S″相强化综合作用所导致的。自然时效时,析出物为GPB区、T相(Al20Cu2Mn3)及S″相(Al2CuMg),其中GPB区、S″(Al2CuMg)相为主要强化相,T相(Al20Cu2Mn3)有细化晶粒的作用,比未预拉伸处理合金的析出相数量多,且析出相分布更均匀,使合金厚板的强度提高。     

热处理对2024铝合金组织与性能的影响

运用力学性能测试的方法系统研究了固溶-时效处理对2024合金组织和力学性能的影响.结果表明:合金经500℃固溶50 min,180℃人工时效10h后可获得最佳的组织性能,硬度为81.3 HRB.     

挤压铸造模温及压力对2024铝合金组织性能的影响

研究了压制压力和模具温度对挤压铸造2024铝合金组织和性能的影响.结果表明:随着压力的增加,合金的铸造缺陷减少,晶粒尺寸变小,超过120MPa时,变化不大;模具温度在200℃时,组织不均匀,存在显微疏松等缺陷,模具温度在300℃时组织粗大;在模具温度250℃、压力120MPa的工艺参数下得到的铸件,缺陷较少,组织均匀,强度高.经过T6工艺热处理后,抗拉强度达到425MPa,伸长率6.9%.     

形变热处理工艺对2024铝合金组织及力学性能的影响

采用力学性能测试、金相显微分析、x射线衍射物相分析、扫描电镜断口扫描等手段,研究了形变热处理工艺对2024铝合金组织及性能的影响。研究结果表明,预变形使合金的时效强化效果提前;随着变形量的增加,延伸率有所下降,合金强度先提高后降低,在变形量为40％时最大。析出相随变形量增大而更加弥散细化;但大变形时效态的合金析出强化相明显减少,表明大变形使合金析出相的析出机制发生了改变。     

深冷处理对2024铝合金挤压棒材组织及性能的影响

试验研究深冷处理对2024铝合金挤压棒材综合性能的影响。包括深冷处理对其显微组织、力学性能、疲劳性能、抗腐蚀性及残余应力等的影响。结果表明,2024铝合金挤压棒材采用495℃1 h固溶、淬火+(-196℃30 min)深冷处理+185℃7 h时效处理后,其综合性能最佳,具有高强度的同时,显微组织、疲劳性能、抗腐蚀性、降低残余应力等均有很大改善。     

Effects of non-isothermal annealing on microstructure and mechanical properties of severely deformed 2024 aluminum alloy

Microstructure and mechanical properties of AA2024 after severe plastic deformation (SPD) and non-isothermal annealing were investigated. The non-isothermal treatment was carried out on the severely deformed AA2024, and the interaction between restoration and precipitation phenomena was investigated. Differential scanning calorimetry, hardness and shear punch tests illustrate that static recovery and dissolution of GPB zones/Cu–Mg co-clusters occur concurrently through non-isothermal annealing. Scanning electron microscope and electron backscatter diffraction illustrate that non-isothermal annealing of deformed AA2024 up to 250 °C promotes the particle-free regions and also particle stimulated nucleation. Results show that through heating with the rate of 10 °C/min up to 250 °C, the ultimate shear strength and the hardness are maximum due to the presence of S'/S phases which have been detected during non-isothermal differential scanning calorimetry experiment. Also, recrystallization phenomenon occurs in temperature range which includes the dissolution of S'/S phases. The concurrent recrystallization and dissolution of S'/S phase at 380 °C have been verified by differential scanning calorimetry, mechanical properties, and optical microscope.     

机械振动对铸造铝合金组织和性能的影响

分析振动方式对ZL101铝合金消失模铸件组织和力学性能的影响。结果表明,机械振动后合金组织明显细化;垂直振动时,合金晶粒尺寸最小,孔隙率最低,抗拉强度最大;ZL101合金垂直振动后,不同厚度处的组织存在较大差别,厚度越大,振动细化效果越显著。     

Comparison of corrosion- fatigue properties of precorroded 6013 bare and 2024 bare aluminum alloy sheet materials

The corrosion- fatigue resistance of precorroded 6013 bare and 2024 bare aluminum alloy sheet materials was evaluated to compare the effect of corrosion on initiation and propagation of fatigue cracks. The specimens were precorroded in 3.5% NaCl water solution per ASTM G 44 for periods of 4 and 30 days, and then were subjected to cyclic testing to failure in a 3.5% NaCl corrosive environment. The notched 6013 specimens showed better corrosion- fatigue resistance for the longer exposure time only. In all other cases, the 2024 material had better resistance. Fractographic and microstructural examinations sug-gested that the lower corrosion- fatigue life of the 6013 alloy is due to intergranular corrosion. Although the surface corrosion (pitting) on the 2024 alloy appeared severe, there was little evidence of intergranu-lar corrosion in this alloy.     

固溶处理工艺对7449铝合金组织和性能的影响

通过硬度、电导率、拉伸试验及金相分析,研究了在460、475、490℃分别保温30、60、120 min的固溶工艺对7449铝合金组织和性能的影响。结果表明,475℃×1 h是该合金最优的固溶工艺,此时合金的综合性能最佳;且固溶处理＋自然时效态合金的抗拉强度、屈服强度和伸长率分别为561．32 MPa、362．19 MPa、22．92％;合金的固溶处理过烧温度为490℃;在固溶处理中,固溶温度比保温时间对该合金性能的影响更大。     

Analysis on microstructure and mechanical properties of aluminum alloy

Dissimilar metal joining between 5A02 aluminum alloy and AISI 304 stainless steel was conducted by gas tungsten arc welding with ZnAl15 and AlSi12 flux-cored filler metals,and the effect of the filler ...     

Electron beam welding of SiCp/2024 and 2219 aluminum alloy

SiC_p/2024 matrix composites reinforced with SiC particles and 2219 aluminum alloy were joined via centered electron beam welding and deflection beam welding, respectively, and the microstructures and mechanical properties of these joints were investigated. The results revealed that SiC particle segregation was more likely during centered electron beam welding (than during deflection beam welding), and strong interface reactions led to the formation of many Al₄C₃ brittle intermetallic compounds. Moreover, the tensile strength of the joints was 104 MPa. The interface reaction was restrained via deflection electron beam welding, and only a few Al₄C₃ intermetallic compounds formed at the top of the joint and heat affected zone of SiC_p/Al. Quasi-cleavage fracture occurred at the interface reaction layer of the base metal. Both methods yielded a hardness transition zone near the SiC_p/2024 fusion zone,and the brittle intermetallic Al₄C₃compounds formed in this zone resulted in high hardness.     

Microstructure characteristics and mechanical properties of rheoformed wrought aluminum alloy 2024

The microstructure characteristics and mechanical properties of 2024 wrought aluminum alloy produced by a new rheoforming technique under as-cast and optimized heat treatment conditions were investigated. The present rheoforming combined the independently developed rheocasting process, named as LSPSF (low superheat pouring with a shear field) process, and the existing squeeze casting process. The experimental results show that LSPSF can be used to prepare sound semi-solid slurry within 25s to fully meet the production rate of squeeze casting. The primary α (Al) presents in mean equivalent diameter of 69μm and shape factor of 0.76, and features zero-entrapped eutectics. Compared with conventional squeeze casting, the present LSPSF rheoforming can improve the microstructures and mechanical properties. An optimized heat treatment results in substantial reduction of microsegregation and significant improvement of mechanical properties, such as yield strength of 321MPa, ultimate tensile strength of 428MPa and elongation of 12%.     

回归再时效工艺对7055铝合金板材组织及性能的影响

通过TEM、SEM、DSC等分析及拉伸试验、电导率测试,对7055铝合金板材回归再时效后的显微组织、性能进行了系统研究。结果表明,随着回归时间的延长,回归再时效处理后的合金强度先升高后降低,导电率单调升高。与T6态相比,合金经回归再时效处理后,晶界析出相间距变大,呈断续分布,且晶内强化相的尺寸也发生了一定程度的粗化。当合金板材的回归再时效工艺为121℃×24 h+170℃×30 min+121℃×24 h时,7055铝合金板材的综合性能最优,抗拉强度达630.75 MPa,屈服强度达588.75 MPa,导电率达34.75%IACS,断裂机制为混合型断裂。