余热热处理对Al-Si-Cu合金铸件组织和性能的影响

研究了余热热处理工艺对Al-Si-Cu合金中Cu元素的固溶效果、共晶Si颗粒形貌及尺寸变化、以及该工艺对合金铸件力学性能的影响.结果表明,余热热处理工艺条件下,铸件可以在更短的时间内获得理想的固溶效果.通过分析铸件微观组织显微可知,余热热处理工艺可以通过缩短固溶处理时间有效地抑制共晶Si颗粒的粗化,在4h的固溶处理中Si颗粒平均尺寸持续减小且未出现粗化趋势.采用相同工艺参数,余热热处理工艺条件下制备的单铸试棒抗拉强度比传统T6热处理工艺提升约15%.     

热处理对挤压态Al-Zn-Mg-Cu合金显微组织和力学性能的影响

采用扫描电镜、硬度测试、拉伸试验及冲击性能测试,研究了3种不同热处理后Al-12Zn-2.4Mg-1.1Cu-0.3Zr-0.15Ni-0.12Mn(质量分数,%)合金显微组织演变与力学性能的变化。结果表明:经T6处理合金的组织主要为α-Al基体、η′和η析出相,合金的平均硬度和抗拉强度分别达到210 HV和597 MPa,高于T4和T5工艺下的合金硬度和强度。η′和η相对于基体有一定的可动性,使合金的塑性降低,T6态合金的伸长率略低于T4态。T4和T5态合金的冲击断裂机制为脆性断裂,T6处理后合金的冲击性能得到明显改善,断裂机制为韧脆混合断裂。挤压态Al-Zn-Mg-Cu合金宜采用T6热处理工艺。     

用三乙胺冷芯制芯中心生产柴油机缸体主体芯

根据柴油机四缸缸体的结构特点及实际生产情况,设计了三乙胺冷芯制芯中心。介绍了制芯工艺流程、砂芯的组合及锁芯工艺。上述设备和工艺已成功地应用于制作485、490、4L68/88、4B28TC等柴油机缸体主体砂芯并取得了较好的效果,为生产形状复杂、薄壁、洁净发动机缸体和缸盖类铸件提供了可靠的条件。     

Estimation of local fatigue behaviour in A356–T6 gravity die cast engine head based on solidification defects content

Al–Si–Mg cast alloys have widespread applications, especially in the aerospace and automotive industries, due to their excellent combination of castability and high specific strength. Among Al–Si alloys, hypoeutectic A356 (Al–7Si–0·3Mg) ranks as one of the most widely used for the production of a variety of components, including engine blocks and engine heads, due to its excellent castability and good mechanical properties. The microstructure of this alloy greatly depends on chemical composition, solidification conditions, metal soundness and heat treatment. Furthermore, its mechanical properties are strongly affected by solidification microstructure and defects, which can vary greatly in complex shaped castings. Among the different microstructural features, only secondary dendrite arm spacing and percentage defect content can currently be predicted with sufficient accuracy by casting simulation software. This makes the prediction of the fatigue life of complex shaped Al–Si castings very difficult, since it is widely accepted that fatigue behaviour mainly depends on the size of solidification defects (gas pores and cavity shrinkages). In this study, the experimental work was carried out on an industrial A356–T6 gravity die cast engine head, with the aim of finding relationships among the main microstructural features and solidification defect parameters. The goal of this analysis was to correlate the defect size, which is the most important variable affecting the fatigue behaviour, to the other microstructural parameters that can be predicted by casting simulation software. Moreover, by applying literature models for fatigue behaviour prediction, based on maximum defect size, the local expected fatigue life/fatigue limit on a section of the casting will be evaluated and compared with those obtained by rotating bending fatigue tests. This study would demonstrate the effectiveness of a new approach of coengineering design, with a strong synergy between the structural finite element method and the casting simulation process, able to estimate the local fatigue strength in complex shaped A356 castings.     

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.     

发动机铸件的清理技术成功案例潍柴缸体清理线

大马力发动机缸体铸件清理一直是铸件生产中的关键,铸件清理生产效率、职工劳动强度、铸件清理质量、环境污染、生产自动化水平是清理生产中的焦点。潍柴动力股份有限公司铸造二期项目大件清理工部采用新的清理流程及技术装备,经生产检验可靠地解决了以上清理生产中的难点。     

论砂型铸造铸件下箱优先设置

简述了发动机缸盖类铸件、轮类铸件、框架类铸件、泵壳阀类致密性铸件等几种典型铸铁件采用将铸件分割置于上、下型的做法,甚或是铸件全部设置于上型的工艺方案,分析了其容易导致气孔、浇不足、冷隔、缩孔、缩松、错边等铸造缺陷的原因。采用铸件全部设置于下型的工艺方案后,因其具有型腔排气充分、可优化设计浇注系统、可优化设置冒口系统、铸件错箱缺陷少、铸件加工余量少等优点,生产实践表明,采用此工艺后铸件合格率大幅提高,可获得内部组织更加致密、外形更加美观的高品质铸件。     

Al-Si合金挤压铸造工艺研究

以工业ZL102合金为原材料,采用正交试验方法,研究了挤压铸造工艺参数对Al-Si合金挤压铸造件热处理前后的力学性能和显微组织的影响.结果表明,挤压铸造组织比常压金属型铸造组织细小;挤压铸造件经过热处理之后,组织比热处理前均匀,晶粒细小,抗拉强度比热处理前提高了4.5％,而伸长率在热处理前平均是0.74％,热处理后提高到1.78％;对9组试验进行分析比较,最终得出热处理后的最优方案:压力为100 kPa,模具预热温度为150℃,合金浇注温度为660℃,保压时间为14 s.     

灰铸铁缸体铸件的典型缺陷案例分析(1)

介绍了在开发和生产大众系列汽车发动机缸体过程中,不同铸件出现的水套断芯、铸件表面烧结粘砂、缸孔孔眼打压渗漏等典型缺陷案例,对它们产生的原因进行逐一排查,通过不断改进工艺和更换新材料,深化操作,严控工序质量,使铸件的各种缺陷得到有效控制,最后指出:影响缸体铸件质量的因素较多,应细心探索难以发现的细节,把工艺改进与工艺管理...     

复合孕育剂对WD615气缸体组织和性能的影响

利用金相显微镜、拉伸试验机分析了含ReCrMnSi的复合孕育剂对WD615气缸体组织和抗拉强度的影响。结果表明,加入0.20%～0.40%的含ReCrMnSi孕育剂可以明显改善WD615气缸体的孕育效果,能够获得均匀分布的A型片状石墨,同时细化珠光体组织,但对共晶团数量和基体组织没有明显影响,铸件性能明显提高,抗拉强度达到280MPa～310MPa。     

热处理工艺对ZG15Cr2Mo1钢铸件焊接热影响区性能的影响

针对ZG15Cr2Mo1钢铸件焊接后热影响区硬度过高的问题,通过试块试验对比分析了不同焊后热处理工艺对试块焊接三区硬度及拉伸性能的影响,对铸件本体缺陷修复焊接后采用不同的焊后热处理工艺进行验证,确定了符合力学性能要求的ZG15Cr2Mo1焊后热处理工艺,在保证铸件本体拉伸性能的同时,焊接三区硬度不超过241HBW.     

4JB1发动机缸体缸盖的铸造工艺特点及质量控制

阐述了4JB1发动机缸体缸盖的铸造工艺特点及采用的主要技术措施,提出了控制其生产质量的方法。     

V型柴油机气缸体铸造工艺设计

本文阐述了V型柴油机气缸体的铸造工艺设计要点,对大缸芯制芯及组芯工艺开发过程做了重点介绍。通过工艺验证,该工艺满足产品技术要求,毛坯尺寸准确、生产效率高,铸件缺陷少。     

Effect of thermal exposure on the microstructure,tensile properties and the corrosion behaviour of 6061 aluminium alloy sheet

Sheet material of the Al‐Mg‐Si alloy 6061 in the tempers T4 and T6 was thermally exposed at temperatures ranging from 85 to 120°C for 1000 h. The microstructure, tensile properties and the corrosion behaviour in the different heat treatment conditions were investigated using differential scanning calorimetry and transmission electron microscopy as well as performing tensile tests and various corrosion tests. The additional heat treatments, which should simulate aging during long‐term service usage, caused an increase in strength of 6061‐T4 sheet, associated with changes in the naturally aged microstructure. Thermal exposure at 120°C for 1000 h resulted in tensile and corrosion properties being similar to those obtained for peak‐aged sheet. Alloy 6061 in the T6 temper exhibited microstructural stability when additionally heat treated at 85 and 120°C for 1000 h. No significant alterations in the microstructure, tensile properties, and corrosion performance were observed after exposure to slightly elevated temperatures.     

Effect of heat treatment on mechanical and wear properties of Zn–40Al–2Cu–2Si alloy

In order to determine the effect of heat treatment on the mechanical and wear properties of Zn–40Al– 2Cu–2Si alloy, different heat treatments including homogenization followed by air-cooling (H1), homogenization followed by furnace-cooling (H2), stabilization (T5) and quench–aging (T6 and T7) were applied. The effects of these heat treatments on the mechanical and tribological properties of the alloy were studied by metallography and, mechanical and wear tests in comparison with SAE 65 bronze. The wear tests were performed using a block on cylinder type test apparatus. The hardness, tensile strength and compressive strength of the alloy increase by the application of H1 and T6 heat treatments, and all the heat treatments except T6, increase its elongation to fracture. H1, T5 and T6 heat treatments cause a reduction in friction coefficient and wear volume of the alloy. However, this alloy exhibits the lowest friction coefficient and wear volume after T6 heat treatment. Therefore, T6 heat treatment appears to be the best process for the lubricated tribological applications of this alloy at a pressure of 14 MPa. However, Zn–40Al–2Cu–2Si alloy in the as-cast and heat-treated conditions shows lower wear loss or higher wear resistance than the bronze.     

精密组芯造型工艺的应用及展望

随着树脂自硬砂的发展,传统组芯造型工艺在大型、复杂铸件生产中得到大量应用。采用三乙胺冷芯盒法的自动化精密组芯造型生产线已成功应用于汽车零件铸造,如整铸式铸铝冷凝换热器,发动机缸体、缸盖等尺寸精度要求高、工艺复杂的中小铸件的批量生产。综述了三乙胺冷芯盒法的精密组芯造型工艺的发展及其应用,该工艺是砂型铸造实现绿色化、智能化生产的重要途径之一。进一步提高原材料和设备的国产化率,强化生产中的环保措施,无机粘结剂及相关设备的研制与工艺开发是今后发展的方向。     

利用3D打印工艺生产V型燃气发动机缸体铸件

介绍了V型燃气发动机缸体铸件的结构及技术要求,分析了该铸件的生产难点,决定采用3D打印砂芯工艺:两侧砂芯形成铸件的侧面外观结构及冒口,中间整体砂芯则形成铸件的内腔结构和两端面结构,底部2块砂芯形成铸件缸口外观结构和浇注系统,砂芯之间通过凹凸定位台进行定位。生产结果显示:铸件尺寸精度可以达到CT9级,铸件关键区域RT最大为I级,1 MPa水压30 min无渗漏,检验均合格,金相组织和力学性能也均符合技术要求,使用3D打印技术提高了生产效率,提升了产品质量,降低了生产难度。     

The effects of strontium and grain refiner additions on the fatigue and tensile properties of industrial Al-Si-Cu-Mg alloy castings produced using the Ford Motor Company—Cosworth precision sand process

Tensile and fatigue properties of production cylinder block castings are reported. The alloy used is aluminium association alloy 320, an Al-Si-Cu-Mg alloy that has found common use in cylinder block and cylinder head applications. Trials involving modification using strontium and grain refinement using a titanium-boron master alloy were conducted. The effects of these additions on amount of porosity, maximum pore size, tensile properties and mean fatigue strength as well as the novel application of grain refiner are discussed. Grain refinement was found to be of marginal benefit, while strontium additions showed pronounced negative effects on the properties studied.     

喷射成形7475铝合金的显微组织与力学性能

采用全自动控制往复喷射成形工艺制备了大规格7475铝合金锭坯。研究工业规格喷射成形7475铝合金的初始组织、挤压工艺及热处理制度对显微组织和力学性能的影响。结果表明,喷射成形7475铝合金锭坯规格可达Ф360mm×1200mm,晶粒为等轴状,粒度宏观均匀,主要在30～40μm,组织无明显宏观偏析,锭坯致密度达到97%。喷射成形锭坯经小挤压比变形后达到全致密,T6态(480℃×4h+135℃×16h)合金性能最优,σb为625～635MPa,δ为12%～12.6%,表明控制往复喷射成形铝合金锭坯冶金质量优越。     

采用3D打印技术开发柴油机气缸体铸造工艺

介绍了直列4缸柴油机气缸体的铸件结构及技术要求,分析了采用传统工艺生产铸件存在的问题。详细阐述了基于3D打印技术设计的一套组芯、造型工艺,替代传统的手工组芯造型方法。生产结果显示:铸件废品率为4.7%,生产验证过程质量稳定;金相组织和力学性能检测结果均符合技术要求;铸件尺寸、表面质量、气密性检测等按照相关规范检验合格,经内部检测,铸件表面粗糙度小于25μm。3D打印成型技术的使用,简化了操作过程,降低了生产难度,提高了生产效率,推动了汽车发动机新型气缸体的研发进度。