AA6061铝合金正方形截面管胀形工艺研究

AA6061铝合金挤压管材在常温下强度高但塑性差,难以成形复杂形状零件。基于此,提出了固溶处理+固体颗粒介质胀形+人工时效的工艺流程,通过固溶、淬火和时效等热处理工艺调整铝合金变形前后的力学性能,应用固体颗粒介质胀形技术实现管件塑性成形。以AA6061挤压铝合金管为研究对象,分析了固溶处理工艺参数对合金力学性能的影响,发现管材经固溶温度560℃且保温120min处理后,其延伸率提高3倍以上,强度和硬度也大幅降低,使合金管材的成形性能指标显著提高,具备了固体颗粒介质胀形管件的条件;对合金固溶处理后再人工时效处理的试验研究表明,人工时效温度180℃且保温360min时合金塑性下降,强度和硬度等性能指标均可恢复至初始状态。基于铝合金热处理工艺特征的研究,采用固溶处理+固体颗粒介质胀形+时效处理的工艺流程,成功试制了AA6061铝合金典型的正方形截面管件,其环向最大展长率可达34%。     

等径角挤压对铸造GH696合金力学性能的影响

为了提高铸造GH696高温合金的力学性能,对该合金在1 000℃进行了等径角挤压变形,对经挤压变形及热处理后的组织与性能进行了研究。结果表明:该合金铸态组织经等径角挤压后得到了显著的细化;铸态合金经挤压变形后进行热处理时会发生再结晶;随挤压道次的增加,铸态组织的特征逐渐减少,强度和塑性得到提高;铸态合金经挤压变形和热处理后,即使还保留少量的铸态组织特征,但其强度和塑性均可达到锻态的水平。     

镁合金等径角挤压的研究与进展

对等径角挤压工艺的基本原理及其工艺参数在挤压过程中对镁合金显微组织、力学性能的影响,等径角挤压过程中镁合金的晶粒细化机理、变形机理及其微观结构、力学性能等的演变规律作了综述,并对等径角挤压镁合金超塑性研究现状和镁合金等径角挤压发展趋势作了介绍.     

化学成分和热处理工艺对1Cr10Mo1NiWVNbN转子钢力学性能的影响

采用力学性能测试和显微组织分析等方法研究了化学成分和淬火温度、回火温度、淬火冷却速率及回火冷却速率等热处理工艺参数对1Cr10Mo1NiWVNbN转子钢力学性能的影响。结果表明:为获得最佳的综合力学性能,钢中碳、氮含量宜控制在中下限,钒、铌含量宜控制在中上限,镍、锰含量宜控制在上限,铬含量宜控制在下限;随淬火温度的提高,试验钢强度不断增加,韧性下降;随二次回火温度的提高,强度下降,塑性略有增加,冲击功增加,但为满足技术条件的要求,二次回火温度需高于690℃;随淬火冷却速率的降低,强度、塑性、韧性均降低;随回火冷却速率的降低,强度略有增加,韧性略有下降。     

挤压AZ63A合金固溶处理工艺的确定

为提高AZ63A(Mg-Al-Zn)变形镁合金的塑性性能,研究了固溶处理温度和时间变化对合金组织与性能的影响.结果表明:随着温度的提高或固溶时间的延长,一方面可以使更多的第二相溶入基体中,使得材料的塑性得以提升,而另一方面由于在热处理过程中晶粒随之长大,降低了包括塑性在内的诸多力学性能;最终确定在385℃下固溶处理12 h可以使AZ63A镁合金在抗拉强度无明显变化的情况下大幅度提高伸长率,是该合金较为合适的固溶处理工艺.     

矿用液压支架销轴结构的热处理工艺研究

以ZFY12000/25/42型液压支为例,对该型号支架中使用的销轴结构材料的热处理工艺进行了详细分析.实验结果表明:回火温度对材料的综合力学性能有显著影响,随着回火温度的升高,材料强度和硬度逐渐降低,而韧性则不断升高.结合销轴结的实际生产和使用情况,最终确定的回火温度为620℃,能够保障结构的综合力学性能满足使用需要.     

热处理对21-6-9钢性能及显微组织影响

热处理工艺对单相高强度21-6-9奥氏体不锈钢显微组织及力学性能影响显著。本文在固定其他热处理工艺参数情况下,分别对固溶处理温度,固溶冷却方式,时效处理温度进行研究,结果表明:固溶温度对21-6-9钢低温韧性及晶粒尺寸影响显著,1050℃是其最佳固溶处理温度;固溶冷却方式对其力学性能影响不明显,但对其晶粒尺寸有较大影响,其中水冷处理方式能够使21-6-9钢得到尺寸均匀且细小的晶粒组织;时效温度对其低温韧性存在影响,表现为时效温度过高(≥600℃)会导致低温韧性明显下降。经过适当的热处理工艺处理,实现21-6-9钢屈服强度不低于438MPa,断口伸长率47%,断口收缩率不低于75%,同时具有良好的塑性及低温韧性。     

热处理对机床主轴用40Cr、65Mn钢力学性能的影响

以机床主轴用40Cr、65Mn钢为研究对象,对其不同热处理工艺下的力学性能进行了测试研究。实验结果表明:随着回火温度的升高,65Mn钢和40Cr钢力学性能有着相同的变化趋势,抗拉强度和屈服强度下降,伸长率和断面收缩率升高,硬度下降,耐磨性变化不显著。在相同的热处理条件下,65Mn钢比40Cr钢强度高、塑性差、耐磨性好、综合力学性能要更好。两种材料在用于机床主轴时经过调质处理便可很好地满足生产需要。     

热处理工艺对22Cr双相不锈钢拉伸性能的影响

研究了热处理工艺对22Cr双相不锈钢拉伸性能的影响,并对断口形貌进行了分析.结果表明:在950～1 150 ℃固溶2 h,其强度和塑性与固溶温度呈复杂关系,在950℃和1 150℃固溶处理的强度比1 050℃的高,但塑性降低;1 050℃固溶后,在850℃时效处理材料强度有所提高,塑性明显降低;1050℃固溶后,在475℃时效处理材料强度明显提高,塑性略有降低.固溶处理后微观断口以韧窝为主要特征;850℃时效处理后断口出现解理的小平面和二次裂纹;475℃时效处理后断口以韧窝为主并伴有局部的解理断裂.     

ZCuAl10Fe3和ZCuAl10Fe4Ni4铸铜合金研究

本工作针对隔膜泵支撑套研制,对比研究了ZCuAl10Fe3和ZCuAl10Fe4Ni4铜合金在不同热处理条件下的力学性能变化规律。Ni合金化显著提高了合金强度和硬度;热处理显著改变合金的力学性能,在淬火＋回火状态合金具有最高的硬度和强度,并保持一定的塑性。     

The effect of equal channel angular pressing on the mechanical and magnetic properties of 09Γ2C steel

The physical and mechanical properties of 09Γ2C steel that was subjected to strengthening by intense plastic deformation using the method of equal channel angular pressing (ECAP) are studied. An unambiguous interrelationship between the magnetic (coercive force, maximal permeability, Barkhausen magnetic noise parameters) and mechanical (rupture limit, conditional yield strength, relative elongation and narrowing upon damaging) characteristics of 09Γ2C steel, which was strengthened using ECAP following different technological regimes, is demonstrated. Therefore, it is possible to estimate the strength and plasticity characteristics of the analyzed material based on the measurement of its magnetic parameters. It has been revealed that under conditions of uniaxial tension in the range from 0 to (0.2–0.6) of the conditional yield strength (depending on the ECAP regime), it is possible to diagnose changes in the stressed state of items that are made of 09Γ2C steel that is hardened in accordance with the ECAP technique using magnetic structuroscopy methods.     

等通道转角挤压技术及其工程应用研究

等通道转角挤压技术（ECAP）是一种目前最有工程应用潜力的大塑性变形（SPD）细晶材料制备技术，具有材料组织细化效果好、加工材料尺寸大等优点。阐述了ECAP处理对材料性能的影响，主要包括材料强韧性能的提高、超塑性的获得以及材料疲劳性能和功能特性的改善。在此基础上，探讨了近年来ECAP技术在工业化应用方面的研究进展，如各种大尺寸材料加工的试验研究、连续化生产和提高加工效率的解决方案等，同时指出了目前研究中存在的不足之处和需要解决的主要问题。     

Effects of solution treatment and sheath on mechanical properties of Al7075 processed by ECAP

Al7075 as a hard-to-work alloy is processed difficultly by Equal channel angular pressing (ECAP) at room temperature. In this paper, experiments were conducted at several heat treatment conditions and also with a new developing strategy using sheath copper to process this alloy at room temperature. Mechanical properties were evaluated by tensile and micro hardness tests. The results demonstrated that the ultimate and yield strength of ECAPed aged samples improved. Tensile test of 4 pass processed samples with copper sheath indicated an increase in the strength in comparison with samples without sheath. The hardness test results showed more uniform distribution of hardness in their cross section for copper sheath casing samples. It was found that by increasing the copper sheath thickness, the hardness variation decreased while the average hardness increased. By considering the time limitation for the process, only solid solution samples without sheath could be successfully ECAPed in 2 passes and samples with sheath could be ECAPed only in one pass.     

Erosion of AISI 4140 steel

The erosion behavior of AISI 4140 steel under various heat treatment conditions was investigated. A variety of microstructures, such as the primary and tempered martensites, varying proportions of martensite and bainite, cementite spheroids embedded in a ferrite matrix and ferrite and pearlite were obtained. The erosion tests were performed in a sand-blast-type test rig. Except in the region where temper embrittlement occurred, the erosion decreased with increasing tempering temperatures. Erosion decreased with the increasing percentage of bainite in the austempered condition and also with increasing tempering time during spheroidization. From the point of view of the mechanical properties, erosion decreased with increasing ductility and decreasing hardness or ultimate strength. The abraded surfaces were also studied using scanning electron microscopy.     

Microstructure and properties of surfacing layers of dies manufactured by bimetal-gradient-layer surfacing technology before and after service

The purpose of this article is to investigate the microstructure and mechanical properties of surfacing layers (wear layer and transition layer) of a hot forging die manufactured by the bimetal-gradient-layer surfacing method, which is based on ZG29MnMoNi cast steel before and after forged 5761 parts on a 63MN hot die forging press. The finite element model of a die was established. Subsequently, a simulation was conducted to analyze the temperature field of the die and its cycle features under working conditions. Microstructure and mechanical property were measured. Results indicated that the microstructure of the wear layer mainly consists of temper sorbite, ferrite and carbides. The transition layer before and after service is mainly composed of both temper sobrite, lower bainite, and a small amount of temper martensite. The mechanical properties of wear and transition layers declined significantly after service. The tensile strength, yield strength, reduction of area, and elongation of wear layer declined by 41.6, 32.5, 28.3, and 24.5 %, respectively. With those indexes the transition layer decreased by 36.6, 34, 24.4, and 19.8 %, respectively. Microhardness and impact energy of wear and transition layers have showed a decrease of 17, 6 % and 51.2, 32.6 %, respectively. The impact fracture mode of both wear and transition layers is typically intergranular fracture after service. As a conclusion, it was determined that the service process sufficiently influenced the mechanical properties of the surfacing layers.     

Constitutive modeling of trip steel and its application to the improvement of mechanical properties

The transformation-induced plasticity (TRIP) steel possesses such favorable mechanical properties as high work-hardening characteristics, tenacity and strength. The strain-induced martensitic transformation, however, strongly depends on the temperature and strain rate imposed, and an appropriate improvement of mechanical properties is realized under quite restricted circumstances. To obtain the required mechanical properties, a constitutive model which can suitably predict the deformation behavior including transformation under a wide range of deformation rate and temperature has been developed by employing Olson and Cohen's model for strain-induced martensitic transformation kinetics. Then, the deformation behavior of a SUS304 (18-8) cylinder has been simulated under different environmental temperature with different strain rates by the thermocoupled finite-element method accounting for the latent heat induced by martensitic transformation. The possibility of the improvement of such mechanical properties of the material as strength, ductility and toughness has been individually discussed.     

Effects of temper condition and post weld heat treatment on the microstructure and mechanical properties of friction stir butt-welded AA7075 Al alloy plates

In this study, AA7075-O and AA7075-T6 Al alloy plates were friction stir butt welded using two sets of weld parameters in order to investigate the effects of temper condition prior to joining and post weld heat treatment on microstructure and mechanical properties of the joints. Another goal of the work is to determine the possibility of restoring the loss of strength in the joint area experienced in welding of this alloy in the age-hardened condition by subsequent heat treatment. The study revealed that the friction stir welding resulted in a strength undermatching when the alloy joined in T6 condition while a significant strength overmatching was obtained in the joints produced in O temper condition. The post weld heat treatment led to a significant recovery in the strength of the joints produced in T6 condition, thus a significant increase in the joint performance. On the other hand, it led to a decrease in the joint performance value of the joints produced in O temper condition although the strength was increased. Furthermore, the post weld heat treatment resulted in abnormal grain growth in the joint area the degree of which depends on weld parameters used and the prior temper condition.     

挤压比对固相再生ZM6镁合金组织和性能的影响

利用固相再生方法在挤压温度为450℃,挤压比分别为11.1:1、25:1和44.4:1的条件下,将ZM6镁合金屑制备成试样,然后进行微观组织观察和力学性能测试。结果表明:ZM6耐热镁合金在挤压过程中发生部分动态再结晶,挤压比越大,动态再结晶程度越大;合金的抗拉强度和延伸率随挤压比的增大而增大,当挤压比从11.1:1提高到44.4:1时,抗拉强度从204MPa提高到248MPa,延伸率从20.7%提高到27.5%。T6态合金的抗拉强度高于挤压态合金的抗拉强度,T6态合金的延伸率低于挤压态合金的延伸率。     

18Ni马氏体时效钢热处理工艺的研究

采用正交试验法探究了固溶温度、固溶时间、时效温度及时效时间对提高18Ni （2240 M Pa级）马氏体时效钢力学性能以及细化晶粒所发挥的作用,并研究了其最佳热处理工艺。研究表明,固溶时间的影响最为显著,时效时间的影响最不明显。将晶粒平均直径细化到Φ7μm时,抗拉强度可提高约100 M Pa。