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41.
树脂自硬砂温控装置改进 总被引:1,自引:0,他引:1
本文分析了引进设备在我国南方高温气候下,连续生产时型砂降温缓慢的原因,提出了增加工业制冷机强制制冷的具体措施,解决了国产设备与进口设备的配套问题,实现了在南方高温季节冷硬树脂砂造型线的连续生产,创造了较可观的经济效益。 相似文献
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This paper describes processes leading to local bake hardening (BH) effects in multiphase steels. The investigations are part of a comprehensive project which investigates the influence of the deformation path and of the temperature and duration of thermal treatments on strengthening in modern multiphase steels, in regard to both local and bulk properties of steel structures. Dual phase (DP), retained austenite steels (TRIP) ‐ both hot and cold rolled ‐ and complex phase (CP) steel are investigated to examine the effect of thermomechanical processing parameters on local bake hardening ability. For this purpose two ways to achieve a local BH effect, i.e. local deformation and local heat treatment, are studied, as well as ageing stability of the adjusted strength. Hardness increased after local deformation through bending as result of work hardening and bake hardening effect. The local heat treatment leads to an improvement of mechanical properties (hardness and strength) and to local strengthening of material. The stability of the local bake hardening effect could be confirmed. 相似文献
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通过对传热基本规律的分析,阐述了涂装工业中传热设备的应用情况,为设计和选用合理的传热元件提供了理论依据。 相似文献
47.
热裂产生的主要原因之一就是型 (芯 )砂容让性差 ,尤其是用自硬树脂砂生产薄壁铸钢件时 ,这个问题显得特别突出。本文对型 (芯 )砂容让性的概念作了评述 ,在借鉴和改进了用于精确定量评价自硬树脂砂容让性好坏的应力试样的基础上 ,设计了裂纹试样。由浇注、加工、测量的结果得出型 (芯 )砂的容让性的准确值和造成铸件热裂的容让性临界值 ,为改善自硬树脂砂的容让性 ,防止铸件裂纹的形成 ,提供了有力的评定标准。 相似文献
48.
T. A. Başer 《Materialwissenschaft und Werkstofftechnik》2015,46(8):829-834
Among the extruded products within the Al–Mg–Si system, AA6082 alloy is regarded as high strength alloy which is used for automotive structural applications. Room temperature storage in between the solution heat treatment and the paint bake cycle is unavoidable problem and undergoes natural aging. Hence, natural aging time in the conventional T4 condition must be modified after the solution heat treatment in order to avoid any hardening during storage before forming processes. The present work was investigated to improve paint bake response of extruded 6082 profiles by employing pre‐aging in between the solution heat treatment and the paint bake in order to obtain sufficient strength for the required in‐service dent resistance. Pre‐aging treatment was performed for 5 min at 180 °C, 200 °C and 225 °C to improve bake hardening response of extruded 6082 profiles. Tensile tests and micro hardness measurements are performed to determine the natural aging effect on mechanical properties. In order to understand the precipitation hardening of this aluminum profile with a different natural aging time, differential scanning calorimetry measurements are performed. 相似文献
49.
实验研究了固溶C和预变形量对超低碳烘烤硬化(ULC-BH)钢的应变时效行为的影响。结果表明:ULC-BH钢在170℃×500 min的长时间烘烤过程中,C原子只发生了位错偏聚,并未出现有些文献报道的碳化物析出现象;在长时间时效处理以后,柯氏气团将达到饱和;当时效时间一定时,固溶C含量与烘烤硬化(BH)值均呈线性关系;当柯氏气团达到饱和时,固溶C质量分数为3.3×10-3%的试样的BH值达到72 MPa,远高于一些文献报道的30 MPa,表明"柯氏气团达到饱和时BH值最大达到30 MPa"的结论并不具有普遍性;位错密度越高,C原子偏聚到位错的扩散距离越短,所以柯氏气团的饱和速度越快;位错密度越高,当柯氏气团达到饱和以后,BH值越小。 相似文献
50.
The present investigation deals with the influence of pre‐straining with or without bake hardening on the strain rate sensitivity of automotive sheet steels in typical crash conditions. The strain rate sensitivity m has been determined by means of dynamic tensile tests in the strain rate range 0.005‐1000 s?1 and in the temperature range 233‐373K. A bake hardening heat treatment at 170 °C for 20 min without pre‐straining does not influence the m‐value in comparison to the base material condition. A small pre‐straining near plane strain condition, as commonly found in outer door panels, or a 10% uniaxial, plane strain and biaxial pre‐straining, as typically used in formed automotive crash components, without bake hardening does not affect the m‐value of sheet steels in comparison to the base material condition. Uniaxial 2% to 10% pre‐straining, longitudinal or transverse to rolling direction with subsequent bake hardening, does not clearly change the m‐value in comparison to the base material condition either. Small differences in the strain rate sensitivity behaviour are rather attributed to experimental scattering without real physical background. 相似文献