摘要多向挤压作是一种大塑性变形法，能够有效细化组织，并拥有工艺简单，成本较低等优点，然而多向挤压还较少应用于黄铜加工上。本文研究了黄铜成分、退火温度、退火时间和挤压道次对多向挤压后黄铜微观组织与力学性能的影响。结果显示：多向挤压可以通过破碎晶粒，动态再结晶和孪晶分割作用使组织发生一定程度的细化。随着含锌量的增多，黄铜在挤压后抗拉强度升高，塑性降低。随着挤压前退火温度的升高，强度先升后降，而塑性变化则相反。而退火时间的延长却都会使强度和塑性呈现先升后降的趋势。本实验中，2道次的挤压获得最好的强化效果。最后得出了最佳屈服强度的工艺参数为含锌量 20%，550℃退火2h，2个挤压道次；最佳抗拉强度的参数则为含锌量 30%，550℃退火 2h，2道次挤压。 28639
毕业论文关键词 黄铜 多向挤压 大塑性变形 正交试验
Title Effect of multi directional compression on microstructure and mechanical properties of brass Abstract Multi directional compression, which can refine the microstructure of material, was a type of severe plastic deformation with low cost and simple craft. The effects of composition, annealing temperature, annealing time and the number of cycle of compression on microstructure and mechanical properties of multi directional compressed brass were investigated by white light confocal microscopy and orthogonal experiment design. The result indicated that, Grains of brass after multi directional deformation the was refined to a certain extent by grain broken, dynamic recrystallization and separation effect of deformation twin. The increase of zinc content resulted in the rise of tensile strength of compressed brass, but the ductility decreased. With the increase of annealing temperature before compression, strength of compressed brass rose first and then decreased, while the ductility changes the opposite. The increase of annealing time made both strength and ductility rose at first and dropped after that. The best strengthen effect was achieved after 2 cycle of multi directional compression. Finally the best compression condition, 20% zinc content、2h annealing at 550℃、 2cycles of compression for yield strength， and 30% zinc content、 2h annealing at 550℃、 2cycles of compression for tensile strength， was obtained in the experiment.
Keywords Brass; Multi directional compression; Severe plastic deformation; Orthogonal experiment
目次
1引言1
1.1黄铜简介.1
1.2多向锻造和多向挤压.6
1.3本文研究意义与主要内容.9
2实验材料与方法10
2.1实验因素与水平.10
2.2样品的制作及预先处理.10
2.3多向挤压过程.11
2.4拉伸试验与组织观察.12
2.5DEFORM软件模拟.14
3实验结果与分析15
3.1挤压黄铜样品的变形情况.15
3.2多向挤压对黄铜微观组织的影响.22
3.3不同因素对多向挤压黄铜力学性能的影响.28
3.4本章小结.35
结论37
致谢38
参考文献39
1 引言 黄铜是一种具有优良塑性及综合性能的材料，广泛应用于各种零件与日常所需品当中时应用最广的铜合金。黄铜的加工方法有热、冷轧，拉伸，挤压等，从而生产各种板带材或管棒线材。加工过程中随着位错等缺陷的增多以及温度的上升，会发生一定程度的回复和再结晶现象，在一定程度上细化了晶粒。为了有效地减小晶粒尺寸，进一步提高黄铜的综合性能，可以以大塑性变形的方式对工件进行加工。目前常见的大塑性变形（SPD）方法有等径角挤压（ECAP）、累积轧焊（ARB）、多向锻造（MF）/多向挤压（MC）、高压扭转（HPT）等[1]。而目前多向锻造/多向挤压的方法还较少应用于在黄铜加工上，故本章综述了与黄铜和多向挤压方面的相关文献，便于进一步探索多向挤压对黄铜性能的影响。 多向挤压工艺对黄铜微观组织及性能影响:http://www.youerw.com/cailiao/lunwen_23566.html