Ti-6Al-4V合金小规格捧材的高速线材轧制与热处理工艺研究

发布时间：2018-04-23 00:39

  本文选题：Ti-6Al-4V合金 + 高速线材轧制　； 参考：《昆明理工大学》2015年硕士论文

【摘要】：Ti-6A1-4V合金是目前使用最广泛、最成熟且具有优良综合性能的(α+β)双相合金。T1-6A1-4V合金小规格棒线材(Φ5-Φ30mm)被广泛应用于航空航天、海洋、电力、化工、医药卫生等众多领域。目前,Ti-6A1-4V合金小规格棒材一般采用二辊或三辊轧制、锻造、拉拔等工艺制备。然而在制备过程中各道次变形量小,稳定性差,棒材尺寸精度低,且生产效率较低。高速线材轧制工艺具有孔型设计精确,轧机的钢性结构稳定,轧制方式高速连续,可用来轧制Ti-6A1-4V合金棒材,解决上述问题。本文采用不同的轧制工艺制备了Φ10mm的Ti-6A1-4V合金小规格棒材,并进行了不同工艺的固溶和时效热处理,研究了不同高速线材轧制工艺和热处理工艺对合金棒材组织与性能的影响,获得以下研究结果：Ti-6A1-4V合金经过高速线材轧制后,合金发生加工硬化和位错的交互作用,使材料的强度和硬度得到提高。初轧温度通常选择在β相变点(960℃)以下进行,棒材组织主要为初生等轴α相少量β转变组织,随温度升高,棒材组织中等轴α相逐渐减少,β转变组织不断长大呈片状分布,棒材强度和硬度增加,而塑性下降；初轧温度接近相变点时,组织主要为层片状β转变组织,棒材的强度和硬度增加,而塑性下降明显,不能达到标准要求。将高速线材轧制方法应用于制备Ti-6Al-4V合金小规格棒材,简化了生产工艺流程、改善了棒材质量的同时提高了生产效率,为了改善合金的组织与性能,需要对棒材进行不同工艺的热处理。Ti-6A1-4V合金棒材在退火态主要由等轴α相和晶间β相组成,温度为930℃时,分别采用空冷、炉冷、水冷三种冷却方式进行固溶,随着冷却速率的加快,等轴α相逐渐消失。炉冷后棒材组织中的a相出现长大,空冷后棒材的组织中出现少量不稳定β转变组织,采用淬火后棒材组织中不稳定β转变组织增多且分布均匀。采用水冷固溶后的试样,分别进行不同工艺时效热处理。随着时效温度升高,β转变组织分解析出α相,组织主要由(α+β)相和β相混合组成,α相不断集聚长大,使组织粗大,棒材抗拉强度降低,延伸率升高。Ti-6A1-4V合金在初轧温度为900℃时,制备出的Φ10mm的小规格棒材,经(930℃,30min, WQ) + (550℃,4h, AC)热处理后,棒材强度和塑性达到最佳配合,抗拉强度为1031MPa,延伸率为12.5%。
[Abstract]:At present, Ti-6A1-4V alloy is the most widely used and mature (伪 尾) dual phase alloy. T1-6A1-4V alloy is widely used in many fields such as aerospace, ocean, electric power, chemical industry, medicine and health, etc. At present, Ti-6A1-4V alloy bars are generally prepared by two or three rollers rolling, forging and drawing. However, in the process of preparation, the deformation of each pass is small, the stability is poor, the precision of bar size is low, and the production efficiency is low. The rolling process of high speed wire rod has the advantages of accurate pass design, stable steel structure of rolling mill and high speed continuous rolling mode. It can be used to rolling Ti-6A1-4V alloy bar and solve the above problems. In this paper, 桅 10mm Ti-6A1-4V alloy bars with small specifications were prepared by different rolling processes, and the effects of different high speed wire rolling and heat treatment processes on the microstructure and properties of the alloy bars were studied. The following results were obtained: after high speed wire rod rolling, the workhardening and dislocation interaction occurred in the alloy Ti-6A1-4V, which improved the strength and hardness of the alloy. The primary rolling temperature is usually below 960 鈩，

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