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微合金化元素对连铸裂纹的影响 总被引:5,自引:1,他引:4
为保证制成品的质量,需要尽可能地减少连铸产品的缺陷。随着热装,薄板连轧及直轧的推广,生产无缺陷的连铸产品也日益重要。这是由于在这些条件下,缺陷的检查与清理变得更加困难的缘故。在连铸产品的各项缺陷中,横向表面裂纹受同合金元素的影响较大。铌是非常有害的,0.01%的铌就会促成裂纹的出现。尽管在钒含量0.15%,氮含量0.2%的场合,也有出现横向裂纹的报道,但含钒钢中,氮低于0.005%时,横向裂纹就不会发生。据信,横向裂纹形成于器,随后在连铸过程,特别是矫直过程中扩张。微合金钢在某一温度范围内,显示出较低的延展率,当在此低延展率区间进行矫直时,就会产生裂纹。铌在深化延展槽,并使其高温区域扩展方面影响显著。铌的这一特点是归因于碳氮化铌的析出。铌的沉积促成低延展失效,并迟滞了再结晶过程。钒对热延展性的影响不那么显著,仅在钢中钒,氮含量较高的情况下,其延展性才接受含铌钢的水平。向含铌钢中添加钒,可通过使析出相粗化稍微改善延展性。钛对热延展性的影响较复杂,到目前还不完全为人们所知。通过适当选择钢的成分,如降低铌的含量,以钒和氮取代铌,或向含铌钢中添加钒,可将横向裂纹的出现降至最低。设备操作条件如二次冷却策略,对避免横向裂纹的出现也很重要。将矫直温度选在低延展率温度区间以外,也可降低裂纹的出现。 相似文献
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研究了微量铌对高饱和磁感应强度软磁合金冷变形加工性能的影响,结果表明,在铁钴软磁合金中添加微量铌,在淬火后合金冷轧不裂.同时对加铌铁钴合金进行了热模拟实验和软化退火实验,结果表明,加铌铁钴合金的延展性较好,可以采用低温加工,而初轧后铁钴合金的退火时温度应高于其无序-有序转变温度730℃,才能使合金有效软化,以便于合金的进一步轧制. 相似文献
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采用单轴压缩试验分别对空心玻璃微珠(HGB)和丁腈橡胶粉末(PNBR)填充的聚丙烯(PP)复合材料进行压缩性能和吸能特性研究,通过测定基于摆锤冲击试验的冲击韧性对材料的吸能能力进行验证,并采用扫描电子显微镜观察材料的微观形貌.结果表明:空心玻璃微珠增加聚丙烯的刚度并降低延展性,粉末丁腈橡胶减小聚丙烯的刚度并提高延展性;吸收相同能量时,粉末丁腈橡胶/聚丙烯体系产生的应力响应最小;根据吸能效率,空心玻璃微珠/聚丙烯体系的设计应力应高于粉末丁腈橡胶/聚丙烯体系;理想吸能效率的最大值出现在相对平缓的屈服阶段;冲击试验结果证明空心玻璃微珠和粉末丁腈橡胶都能改善聚丙烯的吸能特性. 相似文献
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4032合金具有良好的耐磨性和低的热膨胀系数被广泛应用活塞等领域。未经变质处理的4032合金中共晶硅和初晶硅呈粗大的片状或针状,这种组织的存在明显降低了合金的力学性能,尤其是塑性。本文通过选用不同的变质剂进行变质试验,获得了4032合金无初晶硅,共晶硅尺寸细小均匀的组织,达到国际同类产品水平。 相似文献
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《Canadian Metallurgical Quarterly》2013,52(3):291-315
AbstractCreep-rupture tests have been conducted on a variety of alloys made from high-purity aluminum to which was added iron and silicon, both separately and in combination. The investigation was designed to provide information on the creep-rupture embrittlement of aluminum as influenced by composition and temperature, and to establish the rate at which embrittlement occurred in the tests.Iron, by itself, was found to embrittle aluminum. The embrittling effect of silicon, by itself, was negligible. Tests on alloys containing iron alone had a tendency to show minimum ductility at intermediate times to failure. Alloys with both iron and silicon also showed minimum ductility at about the same time to failure, but this minimum was at lower ductility values, and remained constant, for each test, at longer times to failure. Increments of iron above about 0.1 per cent do not necessarily confer increasing embrittlement.Annealing at higher temperatures improves the ductility of these alloys, as shown by tests at lower temperatures.The rate of embrittlement, at testing temperatures where embrittlement is pronounced, is very slow in the early stages of a test but accelerates rapidly near the end.The results of the investigation confirm a previously stated postulate that impairment of cohesion across grain boundaries, by impurities accumulated in the course of creep-rupture tests of metals, is a necessary and sufficient condition for the development of intercrystalline embrittlement. 相似文献
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The influence of 001% to 025% of Aluminum content (in mass percent) on the mechanical properties and cold workability of low thermal expansion Fe-33Ni-15Co sheets in the annealed and hot rolled condition was investigated. Addition of Al up to 015% resulted in the increase of ductility and toughness and improvement of workability. Besides, achievement of fine grain structure and increase in the amount of annealing twins caused ductility to improve. Addition of Al higher than 015% led to the increase in oxidation reaction during melting process and to refine under argon atmosphere. This caused the volume fraction of Al containing inclusions to increase and consequently the ductility and toughness to decrease. 相似文献
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在铝黄铜(72.5Cu-22.7Zn-3.4Al)中添加微量钴(0.2%,0.4%,0.6%),研究微量钴、熔炼铸造工艺及加工工艺参数对轧制法生产的带材的机械性能的影响。探索采用铝黄铜替代目前广泛使用的弹性铜合金材料-锡磷青铜的可行性。研究结果显示:钴能有效减少铸态合金的晶粒尺寸、改变晶粒的形状,提高合金的抗拉强度、硬度,并保证合金具有较好的延展性。铝黄铜中添加0.4%钴,采用合理的加工工艺生产出的黄铜带具有比锡磷青铜更优异的性能,0.25mm厚的带材,其抗拉强度可达840.4MPa,伸长率为2.8%,维氏硬度值为228,比特硬状态的QSn6.5-0.1带材的抗拉强度最大值(805MPa)提高了4.4%,满足弹性元件的使用要求;同时,由于该黄铜中含有22.7%的锌,可有效降低成本,具有实际应用价值。 相似文献
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Therehavebeenconsiderableinvestigationsonintrinsictoughening.Theatentionhasbenpaidprogresivelytothemechanismofextrinsictoughe... 相似文献
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通过正交试验L_(16)(4~5)得出最佳的稀土泡沫铝合金制备工艺参数:发泡剂的含量0.15%、发泡温度680℃、搅拌时间3min、保温时间10mim;研究稀土添加剂量对泡沫铝材料机械性能的影响,用熔体发泡工艺制备出了低成本、结构可控的高强度稀土泡沫铝合金。 相似文献