浅谈杂质元素Zn对6063合金型材表面预处理质量的影响

首先从金属学理论的角度出发，分析了铸锭质量、挤压材的组织状态对６０６３合金型材表面预处理质量的影响；其次，从化学、电化学理论观点出发，指出各种缺陷的腐蚀类型及腐蚀机理，从而有力地说明了６０６３合金中杂质元素Ｚｎ含量的高低对型材表面预处理质量的影响作用，并由此也提出了工艺改革措施。     

2A12-O铝合金型材满足力学性能要求的生产工艺研究

对于用户需要的不同规格2A12-O铝合金型材,以及产品标准中要求的不同试样条件,对生产中出现的力学性能不达标的情况进行了梳理并分析其原因。试验研究了铸锭是否均匀化处理、挤压温度、型材退火工艺制度对其力学性能的影响,着重关注了各工序工艺参数的相关性;通过金相组织、偏光组织分析了型材再结晶程度、化合物的析出程度与相应状态力学性能的关系与影响情况;通过分析与试验,确定了合适的工艺参数匹配,使型材的各项力学性能满足标准及用户的要求。     

纵梁弯曲模及取料机械

通过对型材弯曲的工艺分析、模具设计及模具调试的总结，说明了型材的过程中常见的缺陷及消除方法，在型材、管理材的成形方面有一定的代表性。同时也介绍了一种简便衫的取料机构，可为冲模设计工作者提供有益的参考。     

铝合金大型异形空心型材挤压技术解析

全面系统地论述了铝合金大型异形空心型材的生产方法和艺路线，模具设计与制造，挤压工艺及质量控制等方面的关键技术问题。着重分析了挤压过程中出现的主要问题及解决办法。特别是对大民面多孔薄壁异形空心型材的成形问题、模具结构要素设计和修模等疑难技术问题进行了详细的解析，提出了获得优质大型异形空心型材的技术条件和最佳工艺方案与参数。     

影响6063铝合金挤压型材抛光特性的冶金因素

研究了各种冶金因素对6063合金挤压型材的苛性蚀洗和阳极氧化抛光特性曲线的影响。铁含量高低的影响最为重要,铁含量较高(>0.20％)会促使产生更为无光的表面。铸锭均匀化及挤压工艺对苛性蚀洗特性曲线的影响在其次,因为坯料预热和二次加热温度较低能促使产生更好的漫射表面。然而采用这些工艺,经抛光处理后的挤压型材难于达到最佳机械性能。人工时效工艺(状态)对所研究的冶金因素的影响最重要,时效至最大硬度的材料(T6状态)呈现最令人满意的无光表面,过时效材料(T52状态)次之,自然时效材料(T4状态)则呈现最光亮的表面。简要讨论了6063合金挤压型材抛光过程中出现的某些缺陷,包括软点条纹、“镀锌点”。     

水平连铸结晶器内铁水流动及其对力学性能的影响

通过铸铁水平连铸对比试验,研究了铸铁水平连铸过程中结晶器内铁水的对流流动状态及重力偏析等造成铸铁型材沿型材断面力学性能的不均匀性.结果表明, 采用合适的工艺措施可以促进离析现象,并细化组织,有助于提高水平连铸铸铁型材断面力学性能的均匀性.     

6063-T52铝合金型材时效工艺制度研究

目前我国标准中尚没有6063铝合金T52状态型材的力学性能规范,而美国ASTM、AMS的有关标准中对6063-T52铝合金型材力学性能的最小值至最大值的范围有明确规定。在生产出口型材过程中有时出现型材质量不稳定的情况,为此,试验研究了时效工艺对6063-T52铝合金型材力学性能的影响。结果表明,(140±5)℃4 h和(185±5)℃2.5 h两种时效制度处理的型材,能够达到ASTM、AMS有关标准中规定的力学性能要求。     

7A04-T6铝合金挤压型材热处理

对7A04-T6合金型材热处理制度进行深入研究,制定出合理的工艺制度,使其生产出的T6状态型材的各项性能均能达到指标要求。     

6082铝合金型材缩尾、成层缺陷的分析与解决

通过对型材宏观、微观组织分析,研究了挤压工艺及模具设计对6082铝合金型材缩尾、成层缺陷的影响。结果表明,降低挤压速度及优化模具结构,能够有效解决型材缩尾、成层缺陷问题。     

7B04-T6铝合金挤压型材热处理

对7B04-T6合金型材热处理制度进行深入研究,制定出合理的工艺制度,使其生产出的T6状态型材的各项性能均能达到指标要求.     

时效制度对Al-Zn-Mg-Cu铝合金应力腐蚀敏感性的影响

采用恒载荷拉伸应力腐蚀试样、恒变形C环应力腐蚀试样以及预裂纹双悬臂(DCB)试样,对不同时效制度处理的7B04预拉伸厚板的应力腐蚀性能进行测 定,并进行了扫描电镜断口形貌分析.研究表明,其抗应力腐蚀性能与时效制度密切相关,从峰值时效T6状态到过时效T74、T73状态,应力腐蚀敏感性依次降低.预拉伸厚板T6状态的应力腐蚀门槛值为120 MPa,而T74状态的应力腐蚀门槛值为300 MPa.T74状态的应力腐蚀开裂应力强度因子KISCC是T6的近2倍,且应力腐蚀裂纹扩展速率(da/dt)也明显降低.T6状态和T74状态的7B04铝合金应力腐蚀断裂为沿晶断裂,并有二次裂纹.而T73状态的断口形貌无典型的应力腐蚀沿晶断裂特征,为孔洞腐蚀特征,而且其KISCC几乎接近KIC.这说明T73状态的7B04铝合金几乎没有应力腐蚀敏感性.     

Influence of relative slip on fretting fatigue behaviour of 2014 aluminium alloy with the age-hardened conditions T4 and T6

The present work deals with the effect of relative slip on fretting fatigue behaviour of 2014 Aluminium alloy with age-hardened conditions T4 and T6 in contact with a dissimilar mating material AISI 1045 steel, using a plane-on-plane configuration. There are a significant number of parameters influencing fretting fatigue behaviour. Relative slip value between the specimen and fretting pad is one of the most important factors. In the present study, the influence of relative slip was evaluated at different cyclic stress levels by using a fretting pad with a single pad span value of 10 mm. The results show the artificial temper T6 is more effective for improving the fretting fatigue life when compared with natural temper T4. This may be attributed to a higher microstructural barrier to the fretting fatigue crack nucleation and initiation, due to having lower values of relative slip with artificial temper T6.     

不同时效态对7150铝合金剥蚀行为的影响

针对老龄飞机7150合金飞机结构普遍存在的剥蚀问题,采用海洋性环境腐蚀试验、透射电子显微镜观测等手段,研究了T6、T73和T77时效态7150合金剥蚀行为。研究结果表明：T77时效态抗剥蚀性能最好,T6时效态抗剥蚀性能最差,T73 时效态介于T77和T6时效态之间。7150-T77合金晶界腐蚀产物的锲力,尚不足以提供其剥蚀扩展所需动力。7150合金时效后的晶界微观组织结构,是抗剥蚀性能的重要决定因素。     

Effect of initial base metal temper on mechanical properties in AA7050 friction stir welds

Abstract

The effect of initial base metal temper on mechanical properties in AA7050 friction stir welds was investigated. AA7050 plates, 6·4 mm thick, with three different heat treatment conditions (T7451, T62 and W), were friction stir welded using nearly identical welding parameters, followed by post-weld aging approximating a T7451 heat treatment. The microstructure, transverse hardness profiles and transverse tensile properties were characterised for these three welds. Experimental results show that preweld heat treatment conditions of AA7050 base metal have significant effect on the mechanical properties of the friction stir welds. Friction stir welding of AA7050 in the W condition, followed by post-weld aging, can change the fracture location from HAZ to weld nugget and increase tensile and yield strengths and elongation in transverse tension, relative to welding in T62 or T7451 conditions.     

多级热处理工艺对铝合金AA7049性能的影响(英文)

T6态高强7xxx系列铝合金对应力腐蚀开裂敏感。采用回归和再时效热处理(RRA)可以提高其抗应力腐蚀开裂性能而不降低其强度性能。研究了多级热处理工艺对7049铝合金性能和组织的影响。通过电导率测量、DSC分析和TEM组织观察,考察合金在不同热处理态的组织变化。DSC分析表明,RRA处理会导致合金的显微组织发生显著变化,RRA处理态合金的组织与T6和T73态合金的组织明显不同。RRA处理可以使合金保持在T6态的强度且获得T73态的热力学稳定性能。     

Influence of post-superplastic forming practices on the tensile properties of aluminum-lithium alloys

The effect of thermal processing following superplastic forming on the tensile properties of aluminum-lithium alloys is addressed. The starting materials consisted of alloys 8090, 2090, and X2095 (a Weldalite™ 049 variant) in the form of commercial- grade superplastic sheet. Experience dictates that post- forming practices aimed at a slightly underaged T6 temper produce balanced engineering proper-ties in these alloys. The objective of this study was to assess the potential to use a T5- type temper by elimi-nating the solution heat treatment and/or cold water quenching steps characteristic of T6 processing. The experimental procedures adopted ensured that the tensile properties compiled were representative of the bulk material Initially, the strengthening behavior of each alloy as a function of temper selection was established. Subsequently, aging practices that resulted in peak strength and balanced properties were identified for the baseline T6 temper and two T5 tempers. The implications for replacing a T6 tem-per with a T5- type temper, including rapid and slow cooling following forming, are discussed on the basis of the results.     

多向锻造7075铝合金的结构和性能

在440℃经多向锻造加工成7075铝合金锻件。研究了锻件的显微组织和力学性能随退火温度和T73回火的变化，TEM和SEM用于分析锻件的晶粒和第二相形态。多向和大变形锻造产生平均晶粒尺寸1．8μm的完全再结晶组织。390℃-450℃退火使晶粒长大到3μm，但位错和第二相分布没有明显改变，这时锻件展现出较低强度和较高延性。T73回火使锻件屈服强度和拉伸强度分别提高280％和210％，而延性同退火样相比并无明显下降，断裂韧性达到51MPam^1/2，可以认为这是沉淀强化的贡献。     

7B04铝合金疲劳断裂性能研究

研究了新型的7B04铝合金预拉伸厚板不同热处理状态的断裂韧性和疲劳裂纹扩展性能变化,试验结果表明,该合金T7451状态的断裂韧性和疲劳裂纹扩展性能明显优于T651状态的性能。     

Effect of heat treatment on the properties of laser-beam welded rheo-cast F357 aluminum

Semi-solid metal rheo-cast F357 aluminum plates were joined by autogenous Nd:YAG laser welding and were welded in either the as-cast (F) condition, T4 temper or T6 temper condition. The weldability of this age-hardenable Al-7%Si-0.6%Mg casting alloy was characterized by assessment of the microstructure in the fusion and heat-affected zones and by measurement of the weld-plate tensile and hardness properties. The low heat input provided by the laser welding process resulted in high cooling rates (450-600 K/s) within the fusion and adjacent heat affected zones. This thermal cycle closely resembles quenching practice for standard solution treatments (500-700 K/s) and as a result the T4 condition was maintained during the welding process. Tensile properties equivalent to the parent metal T6 condition were obtained after exposing welded T4 plates to conventional artificial ageing treatment.     

The stress corrosion cracking behaviour of heat‐treated Al–Zn–Mg–Cu alloy in modified salt spray fog testing

The stress corrosion cracking behaviour of 7075 (Al–Zn–Mg–Cu) alloy have been studied in a salt spray fog chamber with two vapourised aqueous solutions (0 and 5% NaCl). The paper analyses the stress corrosion resistance of 7075 aluminium alloy with several precipitation‐ageing heat treatments. The results are compared with that obtained in 3.5% NaCl aqueous solution at 20 °C. The salt spray fog testing has permitted a good evaluation of SCC susceptibility in 7075 alloy. All temper conditions studied were susceptible to SCC in the different environments tested. 7075‐T6 temper was the most susceptible, while in all the cases studied 7075‐T73 temper was the least susceptible. Compared to 7075‐T6, 7075‐RRA temper improved the resistance against the SCC process, but the mechanical properties obtained were lower.