Extrusion speed has a significant influence on the extrusion temperature, microstructure and mechanical properties of the material in the repetitive continuous extrusion forming (RCEF) process. In this work, the mechanical properties of Al2024 were improved by adjusting the speed (with a general range of 2–10 rpm) of repetitive continuous extrusion and applying subsequent heat treatment. During the RCEF process, an increase in the extrusion speed from 4 to 8 rpm was found to increase the extrusion temperature and then enhance the solid solution function. The grain size was affected by the combined effect of deformation speed and its induced temperature. A high-strength Al2024 (ultimate tensile strength of 497.6 MPa) with good elongation (12.93%) was obtained by increasing the extrusion speed and conducting solid solution and artificial aging treatments. The main strengthening mechanisms could be attributed to finer grain size and a larger amount of S (Al2CuMg) precipitates.

为正确理解与实施TB/T 3012—2016《铁道货车铸钢摇枕、侧架》,详细介绍了北美铁道协会和我国铁道货车铸钢摇枕和侧架标准的发展演变过程.对铸钢摇枕和侧架标准中有关实物取样力学性能、工艺要求、铸造缺陷、静载荷及疲劳试验等一些具体问题进行分析和说明,并对TB/T 3012—2016的贯彻实施提出意见或建议.

通过合理设计泵轮模型支撑,对泵轮选择性激光烧结的烧结工艺、后处理工艺进行研究,确定了烧结工艺和后处理工艺,烧结出合格的泵轮模型;对模壳焙烧工艺的研究,确定了模壳焙烧工艺,并浇注出合格的泵轮铸件.

通过对ZG25MnCrNi钢化学成分、力学性能、金相组织及硬度分析,揭示钢中贝氏体形成原因.结果表明,由于试验钢中Mn的偏析,易在正火后产生贝氏体组织;采用920℃保温2 h+随炉冷却至600℃后空冷处理能改善贝氏体组织;控制锰铁合金的块度及冷却速度,可预防贝氏体形成.

某铸钢件箱盖存在砂眼、夹渣、缩孔等铸造缺陷,通过对箱盖浇注系统进行模拟、对铸造工艺进行分析,改进了熔模铸造工艺,确定将水玻璃型壳工艺改为水玻璃-硅溶胶复合型壳工艺,并采用低注式浇注系统.经生产验证,采用新工艺生产的铸件实物完全满足使用要求.

对目前主要生产钢背铜基合金双金属滑动轴承的制坯工艺进行了详细阐述,主要从材料选用、钢背与铜基合金的复合工艺及表面处理方面进行了总结和分析.鉴于采用离心熔铸工艺生产且未进行表面处理的钢背铜基合金双金属圆柱形衬套在铁路机车车辆中的成功应用,恳请广大专家和学者对通过合理选材、合理的复合工艺等措施制备的圆柱形衬套进行研究和认证,以避免进行电镀等表面处理,积极响应“绿色环保”号召.

为生产高质量、高性能要求的不锈钢活塞顶,对其化学成分、铸造工艺及热处理工艺进行了优化分析,结合酯硬化水玻璃砂工艺出现的缺陷问题提出了防止措施,为批量生产合格铸件奠定了基础.实际生产经验表明,气孔是生产过程中的主要缺陷,通过减少发气源、增强排气及控制浇注工艺等措施取得了较好效果;在ZG20Cr13基础上添加Ni、Mo合金元素,并采用95 0℃保温2～3h油淬、65 0℃保温2～3h回火的调质处理工艺,满足了零件的性能要求.

以内燃机车用ZG230钢顶不锈钢铸件为研究对象,对其呋喃树脂砂生产工艺过程中的型砂控制、铸造工艺及易产生的缺陷进行了分析和探讨.生产经验表明,通过对型砂及造型工艺过程进行严格控制后,将浇注温度控制在1 550～1 570℃,浇注时间控制在11 ～15 s范围内,在不进行焊修工艺前提下可得到满足要求的合格铸件.

借助SINOVATION软件对磁轭进行三维实体建模及铸造工艺设计,采用MAGMA软件对磁轭铸造工艺进行模拟分析,并对该工艺方案下的铸件进行了实体浇注及质量检测。结果表明:在合理设计浇注系统和冷铁等工艺参数条件下,采用SINOVATION软件计算的模数大小和冒口尺寸能满足铸造工艺要求,为实际生产提供指导。

The 240 en-block piston rings were produced by self-designed shell core in practical plant conditions,and the microstructure and properties of the piston rings were compare with that produced by green-sand.The results show that the technical parameters of the piston rings produced by shell core process can meet the technical criterion of the piston ring completely.The hardness of the piston rings produced by the two processes is almost equivalent,while the complex properties of the piston rings produced by shell core process are better in metallurgical microstructure,bending strength and abrasion resistance etc.

研制了一种能起密封和保温作用,其自重能抵抗球化处理包中铁液与镁反应所产生的压力,且操作便捷的轻型球化处理包包盖,对其制作方法和应用效果进行了详细阐述.实际生产应用表明,与常规球化处理相比,使用轻型包盖可减少烟尘量和镁光,镁的吸收率有较大提高,氧化渣量显著减少,在铁液化学成分、金属液质量等所有条件相同的情况下,可减少球化剂的加入量,保证了产品品质.

The housing castings produced with former casting method had defect revealed by magnetic traces congregation which were analyzed with numeral simulation software and concluded that the defects were the oxide inclusion caused due to the turbulence and splash of the mold-filling iron melt stream and the oxide dross which was formed in the later mold-filling period and then floated to the surface layer and congregated.At last,by adopting bottom gating system,keeping the ingates from striking the mold and core,ensuring enough filling space in the front of filling stream,setting filter before the ingates,and setting nodular iron-special exothermic risers on the hot spots etc.,the secondary oxide dross inclusion was effectively eliminated and the shrinkage defect was also prevented and so that the process yield was increased.

Based on the characteristic study of low temperature thin-wall nodular iron castings produced with furan resin,the principle of foundry technique design is determined,and the in- process quality control of key points and critical procedures for producing thin- wall ductile iron castings with furan resin are outlined in respect of patterns,molding sand,molding,smelting and pouring.

国內机车用铸钢轮心技术条件主要采用TB/T1400-2005《机车用铸钢轮心技术条件》。文中结合实际生产、验收过程中遇到的问题,对该标准的相关规定进行了探讨。按照轮心生产流转中各个检查环节要求对该标准进行总结,并讨论了轮心允许存在的缺陷部位及对缺陷的处理。

为提高铜合金熔炼过程中的冶金质量及操作安全性,研制了一种使用寿命长的中频感应炉炉衬的打结工艺,实际生产应用表明,该炉衬结合强度高,导热性好,烘炉所需时间短,熔炼过程中未出现炉体的内外衬分离和石墨坩埚的架空及开裂现象,且杂质含量少,使用寿命大幅度提高。

针对加热-冷却的循环工况条件下使用的耐火泥材质烧制而成的感应圈内衬易出现爆裂的现象,研制了一种适合该工况要求下使用的新型中频感应圈内衬,对其选材、制备过程及应用效果进行了详细阐述。

The adaptor is an important structural component between bogie and shaft in diesel locomotive.Comparing with domestic counterparts,EMD adaptor has more complicated structure,which blocks the feeding channel.Besides,request of appearance and internal quality of this component is strict.All locations of the casting should be level 3 radiographic testing according to ASTM E446/E186.To achieve the technical request,casting process should be investigated.In this paper,Magmasoft is used to calculate the hotspot in the casting and porosity defects are estimated.The casting process is designed and optimized according to the rule of progressive solidification.The results show with semicircular allowance and insulated riser,the internal quality of casting was assured and reaches the customer's request.

采用模拟软件Magma对铝合金轴箱前盖铸造工艺方案的充型及凝固进行模拟,分析对比了2种方案各自的优缺点。综合考虑,确定采用水平压边胃口顶注方式,并在此基础上采取保温砂套、局部冷却水管激冷等改进工艺,实现了冒口的圆满补缩,铸件获得了良好内部质量。同时在压边冒口下方增设内浇道以及使用过滤片,确保了铸件外观质量。

Despite their excellent friction and wear resistance and considerable fatigue strength,copperbase alloy and aluminum-base alloy sliding bearings are not so attractive due to their insufficient anti-seizure and oil retaining capabilities.In order to satisfy the technical specifications of sliding bearings for diesel engines on high speed and heavy-haul locomotives,steel-backed copper-lead alloy bimetal sliding bearing is produced with induction heating and particle centrifugal melting processes,which is characterized not only by its breakthrough of the limit to properties of alloyed materials,but also by its fine fatigue strength,compliance,oil retaining,corrosion resistance and anti-seizure performance.Practical application proves that the mechanical properties,bimetal bonding strength,fatigue strength,reliability,alloy utilization rate and microstructure of the sliding bearing manufactured with this new process are better than that produced with other techniques.

Production of compound cast iron with scrap steel recarburization in place of conventional pig iron can improve the quality of castings and reduce the cost of production. This paper introduces the selection and properties of recarburizers, analyzes the influence of melting speed and temperature, chemical composition of molten iron, stirring of molten iron, addition of recarburizer and the adding process on the absorptivity of recarburizer, and studies the trend of structures and properties of compound iron with the application of scrap steel recarburizing process.