不同压力对挤压铸造Al-Cu-Mg合金性能的影响

使用挤压铸造工艺制备了高强、高韧Al-4.5Cu-1Mg合金。在挤压力为70MPa下成型后,合金的最大抗拉强度达到288.8MPa、伸长率达到12.8%、HRB硬度达到48.3。通过对该合金力学性能及其显微组织的研究表明,合金的抗拉强度、伸长率以及硬度随着压力的增加而增大,并且在70MPa时达到最大值,70MPa之后继续增加压力,对材料性能影响不大。研究了挤压力对合金的密度和导电性的影响。试验结果表明,合金的密度随着压力的增加而快速增大,在挤压压力为70MPa时达到最大值,然后变化不大。     

挤压铸造半固态A356铝合金的组织与力学性能

采用低温铸造方法制备A356铝合金半固态坯料.在200 t立式油压机上用挤压铸造方法将A356铝合金半固态浆料挤压成件.研究挤压铸造件的微观组织、力学性能,并与液态挤压铸造件进行比较.结果表明,A356铝合金半固态挤压铸造件组织由球形及椭圆形α-Al晶粒和α+Si共晶成分组成,且制件充型完整、无宏观缩孔、组织致密.在比压48.7 MPa,浇注温度575℃,保压时间3s条件下成形的半固态挤压铸造件的抗拉强度、屈服强度、伸长率分别达到278 MPa、225 MPa、13.2％,相比于在比压48.7 MPa,保压时间3s,710℃液态挤压铸造件性能分别提高了8.6％、8.2％、24.5％.A356铝合金半固态挤压铸造成形件具有较高的综合力学性能.     

不同压力下挤压铸造铝铜合金的组织与性能

采用挤压铸造工艺制备出一种新开发的、高强韧铝铜合金.T5热处理状态下其抗拉强度达到433 MPa,伸长率为14%.通过对该合金力学性能及其显微组织的研究表明,铸态和经T5热处理的抗拉强度和伸长率均随压力的增加而增大,在压力为50MPa时达到最大值,但在铸态下,未加压力的铸造合金其硬度高于挤压铸造的合金硬度.随挤压力增加,晶粒明显细化,二次枝晶增加,枝晶间距减小.     

Development of high plasticity Al-Si alloy and its casting process

Aiming to meet the challenge of the shape complexity and high plasticity demanded for the upper connective plate(UCP) in motorcycle,a high plasticity Al-Si alloy named HGZL-02 was developed by optimizing the chemical composition and casting process,Premium UCP castings were obtained by using optimized casting process,Results show that fine and dense microstructure are obtained in the UCP castings,An average of 224 MPa in ultimate tensile strength,149MPa in yield strength and 13.2% in elongation are achieved for T6 heat-treated UPS castings.     

AlSi7Mg合金半固态压铸件热处理强化机理研究

对AlSi7Mg合金(A356)半固态压铸件和液态压铸件进行了不同工艺的固溶与时效热处理，分析了其显微组织与疏松度，测定了硬度、拉伸强度及延伸率等力学性能。实验得出，铝合金半固态压铸件原始态的力学性能优于液态压铸件，并且半固态压铸件时效强化效果尤其明显，拉伸强度可达330MPa以上，延伸率10％以上。这主要是由于半固态压铸件比液压件具有更加致密，且为球状的非树枝晶组织。铝合金半固态压铸件时效强化，机理主要归于弥散析出Mg2Si强化相。     

半固态挤压铸造A356合金在热处理过程中的组织和性能演化

半固态挤压铸造的A356合金首先在540℃下进行固溶处理,随着固溶温度升高,Mg和Si原子逐渐溶解于基体中,并产生了固溶强化作用。抗拉强度、延伸率和硬度在固溶6 h达到峰值,之后合金力学性能随固溶时间延长而下降。在固溶处理之后合金在180℃下进行了不同时间的时效处理。随着时效时间延长,Mg₂Si相逐渐在基体中析出,析出相显著球化细化,尺寸约为2μm。经过对合金组织和力学性能的分析,半固态挤压铸造A356合金的最佳热处理制度为:540℃固溶6h,180℃时效4h。经过固溶和时效处理后的合金抗拉强度达到336 MPa,延伸率达到6.9%,硬度达到1240 MPa,相较于热处理前的性能提升了106.7%。     

Weibull analysis of fluidity and hardness of ultrasonical y degassed secondary Al7Si0.3Mg aluminum alloy

The influence of ultrasonic degassing process on fluidity and hardness of secondary Al7 Si0.3 Mg alloy castings was studied by Weibull analysis. This work makes a contribution about fluidity and hardness distribution of secondary aluminum alloys with ultrasonic degassing phenomena using a two-parameter form of Weibull analysis. Results show that both hardness and fluidity of alloy are improved after the ultrasonic degassing process. Average efficiency of ultrasonic degassing on fluidity measurements is 31.71%, whereas on hardness values is 8.48%. The Brinell hardness of 45.7 and fluidity of 19.5 of Weibull modulus were achieved as the most reliable and reproducible after 45 s ultrasonic degassing process against 15 s and 30 s ultrasonic degassing processes. The value of 70.08 HB is obtained from ultrosonic degassing, which is equivalent to sand casting of primary Al7 Si0.3 Mg aluminum alloy, and the highest value of 56.4 cm for 45 s after ultrasonic degassing of fluidity was measured.     

Semisolid casting using a vertical-injection squeeze casting machine: material flow and tensile properties of Al-7Si-0.3Mg alloy

Semisolid die casting of thixotropic Al-7Si-0.3Mg alloy has been carried out using a vertical-injection squeeze casting machine. The flow of the billet surface layer during casting was determined by X-ray examination of embedded markers. Tensile properties of the castings were then evaluated and metallographic observations were made. The original billet surface layer was found to be largely confined to the surface layer in the biscuit, except for the top of the billet surface, which flowed to the upper surface of the casting. As a consequence, the incidence of oxide inclusions within the casting was very low, leading to high elongation values with low scatter. Significantly lower strength and higher elongation values were observed in the biscuit. This effect was attributed to there being a significantly lower concentration of the solute elements in the biscuit compared to the casting.     

Weibull analysis of fluidity and hardness of ultrasonically degassed secondary Al7Si0.3Mg aluminum alloy

The influence of ultrasonic degassing process on fluidity and hardness of secondary Al7Si0.3Mg alloy castings was studied by Weibull analysis. This work makes a contribution about fluidity and hardness distribution of secondary aluminum alloys with ultrasonic degassing phenomena using a two-parameter form of Weibull analysis. Results show that both hardness and fluidity of alloy are improved after the ultrasonic degassing process. Average efficiency of ultrasonic degassing on fluidity measurements is 31.71%, whereas on hardness values is 8.48%. The Brinell hardness of 45.7 and fluidity of 19.5 of Weibull modulus were achieved as the most reliable and reproducible after 45 s ultrasonic degassing process against 15 s and 30 s ultrasonic degassing processes. The value of 70.08 HB is obtained from ultrosonic degassing, which is equivalent to sand casting of primary Al7Si0.3Mg aluminum alloy, and the highest value of 56.4 cm for 45 s after ultrasonic degassing of fluidity was measured.

     

流变挤压铸造制备LPSO结构增强Mg-Zn-Y-Zr合金及其组织性能

采用流变挤压铸造工艺制备了含有LPSO结构的Mg99.9-3xZnxY2xZr0.1(x=0.5、1、2,摩尔分数,%)合金,研究了合金的微观组织特征及力学性能。结果表明,流变挤压铸造能有效细化合金的微观组织。合金的基体组织由尺寸较大的α1-Mg和尺寸较小的α2-Mg晶粒组成,LPSO结构呈细小的网状结构均匀地分布在晶界处,LPSO结构的含量越低,其细化效果越明显。随着挤压压力增大,合金中LPSO结构的厚度越来越小,当压力达到100MPa后,厚度变化趋缓。与常规重力铸造相比,流变挤压铸造能有效提高合金的力学性能,特别是伸长率。在400MPa下的流变挤压铸造Mg96.9Zn1Y2Zr0.1合金的抗拉强度和伸长率较重力铸造下分别提高了19%和170%。     

Improvement of microstructure,mechanical properties,and corrosion resistance of WE43 alloy by squeeze casting

The WE43 magnesium alloy was prepared by squeeze casting, and the influence of squeeze casting parameters on mechanical properties and corrosion resistance was studied and compared with gravity casting. The gravity cast WE43 alloy shows uneven grain size distribution, and some grains even greater than 90 µm. While, the grain size of the squeeze cast WE43 alloy is mainly distributed in 20–50 µm. The Mg₁₂Nd₂Y phase morphology changes from large lamellar to strips after squeeze casting, whereas Mg₂₄Y₅ phase exhibits no obvious change. The yield strength, tensile strength, and elongation of the gravity cast WE43 alloy are 127 MPa, 157 MPa, and 6%, respectively, and 145 MPa, 193 MPa, and 9.1% for squeeze cast alloy. For the squeeze cast WE43 alloy, the average corrosion rate is 0.6056 mm·year⁻¹ according to immersion test results, and according to electrochemical measurements, the corrosion current density is 78.13 µA·cm⁻², which is better than that of the gravity cast WE43 alloy. Compared with gravity casting, the grains and second phase of the WE43 alloy by squeeze casting are refined, and the mechanical properties and corrosion resistance are improved. This may expand the applications of the WE43 alloy.

     

铸造Al-Mg-Mn合金的显微组织及力学性能

研究了Mg含量、冷却速度、固溶处理对Al-6.8Mg-0.3Mn、Al-3.8Mg-0.3Mn两种合金力学性能的影响。结果表明,随着Mg含量提高,晶界相增多。当Mg含量提高到6.8%时,晶界出现网状组织;随着Mg含量升高,合金强度提高,塑性下降;通过砂型铸造空冷、金属型铸造空冷、金属型铸造淬火来实现不同的冷却速度,发现金属型淬火试样的金相组织中,在晶界附近没有析出网絮状或颗粒状第二相,而强度和伸长率要高于其他两种工艺。两种合金经过430℃×60h固溶处理后,合金的综合力学性能得到大幅度提高。Al-6.8Mg-0.3Mn金属型铸造空冷试样固溶后抗拉强度由280MPa提高到335MPa,伸长率由10.4%提高到20%。     

热处理对半固态A356铝合金挤压铸件组织与性能的影响

将低温浇注制备的半固态A356铝合金坯料加热至半固态浇注、挤压成形。采用正交试验法研究了固溶、时效对半固态A356铝合金挤压铸件组织与力学性能的影响。结果表明,时效时间对抗拉强度、屈服强度、伸长率影响最大,且都是随着时效时间增长先上升后下降;试验6获得较好的综合力学性能,其抗拉强度、屈服强度、伸长率分别为340 MPa、325 MPa、9.56%。     

Influence of technical parameters on strength and ductility of AlSi9Cu3 alloys in squeeze casting

An orthogonal test was conducted to investigate the influence of technical parameters of squeeze casting on the strength and ductility of AlSi9Cu3 alloys. The experimental results showed that when the forming pressure was higher than 65 MPa, the strength (σ_b) of AlSi9Cu3 alloys decreased with the forming pressure and pouring temperature increasing, whereas σ_b increased with the increase of filling velocity and mould preheating temperature. The ductility (δ) by alloy was improved by increasing the forming pressure and filling velocity, but decreased with pouring temperature increasing. When the mould preheating temperature increased, the ductility increased first, and then decreased. Under the optimized parameters of pouring temperature 730 °C, forming pressure 75 MPa, filling velocity 0.50 m/s, and mould preheating temperature 220 °C, the tensile strength, elongation, and hardness of AlSi9Cu3 alloys obtained in squeeze casting were improved by 16.7%, 9.1%, and 10.1%, respectively, as compared with those of sand castings.     

Effect of pressure on microstructures and mechanical properties of Al-Cu-based alloy prepared by squeeze casting

A new high-strength aluminum alloy with better fluidity than that of ZL205A was developed. The effect of applied pressure during squeeze casting on microstructures and properties of the alloy was studied. The results show that the fluidity of the alloy is 16% and 21% higher than that of ZL205A at the pouring temperature of 993 K and 1 013 K, respectively. Compared with permanent-mold casting, mechanical properties of the alloy prepared by squeeze casting are much higher. The tensile strength and elongation of the alloy are 520 MPa and 7.9% in squeeze casting under an applied pressure of 75 MPa, followed by solution treatment at 763 K for 1 h and at 773 K for 8 h, quenching in water at normal temperature and aging at 463 K for 5 h. The improvement of mechanical properties is attributed to the remarkable decreasing of the secondary dendrite arm spacing(SDAS) and eliminating of micro-porosity in the alloy caused by applied pressure.     

An empirical analysis of trends in mechanical properties of T6 heat treated Al-Si-Mg casting alloys

The Al-Si-Mg family of alloys is typically used in the T6 heat treated condition for high integrity casting applications. There are several variables that can influence the tensile properties of these alloys besides the actual ageing treatment employed. These are alloy composition, particularly Mg and Fe content, and secondary dendrite arm spacing or SDAS. Tensile data from samples covering a wide range of Mg content (0.3–0.7%), Fe content (0.05–0.20%), SDAS (20–60 μn) and two ageing treatments (under- and peak-aged), have been collected and analysed empirically. Concise relationships have been determined for yield strength, ultimate tensile strength and elongation to fracture in terms of one or more of the experimental variables. The observed trends are explained in terms of basic metallurgical principles and the predictive use of the empirically-determined equations is qualified. A comparison of experimentally determined properties and those calculated using the derived relationships highlights some important and clear trends.     

Mg对反重力铸造ZL116合金组织和性能的影响

通过OM、XRD以及室温拉伸试验等手段,分析了Mg对反重力铸造ZL116合金显微组织和力学性能的影响。结果表明,随着Mg含量提高,ZL116合金的抗拉强度有所提高,伸长率基本没有变化。反重力铸造方式中差压铸造的ZL116合金力学性能最优,低压铸造次之,调压铸造的力学性能差于重力铸造。随着Mg含量提高,ZL116合金中的强化相Mg2Si含量也随之增加,最终导致ZL116合金抗拉强度提高。     

挤压铸造对Al-Cu合金显微组织及溶质分布的影响

研究了挤压铸造工艺条件下,工艺参数对Al-5Cu-0.4Mn合金显微组织及Cu元素分布的影响。结果表明,合金在25MPa压力下成形时,初生α-Al晶粒尺寸得到明显细化;浇注温度越高组织变得越粗大;升高模具预热温度,晶粒尺寸增大且分布不均匀。挤压铸造改变重力铸造条件下Cu的逆偏析现象,从铸件边缘往心部的Cu含量呈现增加的趋势,主要原因为晶间富铜液相在压力的强制补缩下,通过枝晶骨架通道被挤向铸件内侧。Cu在α-Al基体中的固溶度随着压力的增大而增加;沿径向远离铸件心部,α-Al晶内Cu含量逐渐增加。在挤压力为100MPa、浇注温度为680～730℃、模具温度为200℃的工艺条件下,可获得晶粒细小、组织致密、宏观偏析少的Al-5Cu-0.4Mn合金挤压铸件。     

电磁低压铸造对AlSi7Cu2Mg合金性能的影响

试验研究了电磁低压铸造AlSi7Cu2Mg合金的力学性能,并与重力铸造的进行了对比分析。结果表明,电磁低压铸造AlSi7Cu2Mg合金,其抗拉强度平均值为322MPa,伸长率平均值为4.66%,与重力铸造相比,分别提高了4.89%和23.94%。     

不同凝固压力条件下A356-10%SiC复合材料的微观组织及性能

通过搅拌法制备A356?10%10SiC复合材料,并分别在0.1(重力条件)、25、50和75 MPa压力条件下进行该复合材料的直接挤压铸造成形,研究了铸态和 T6热处理后复合材料的微观组织及力学性能。结果表明：随着挤压力的增大,铸件的增强颗粒?孔洞团簇缺陷减少,并改善了增强颗粒与基体间的结合强度,拉伸强度、硬度和热膨胀系数增加。与铸态复合材料相比,T6热处理后复合材料的抗拉强度和硬度增大而热膨胀系数减小;在重力条件下凝固的复合材料断口处存在增强颗粒?孔洞团簇缺陷,而在挤压力下凝固的复合材料断口未观察到该缺陷,断口特征表明两者存在不同的断裂机制。