Superplasticity in an AZ91 alloy extrusion processed from machined chips
Superplasticity in an AZ91 alloy extrusion processed from machined chips
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由机加工碎片加工而成的 AZ91 合金挤压件的超塑性
DOI：
10.1007/bf00540002
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
K. Higashi
中科院分区：
文献类型：
--
作者：
M. Mabuchi;K. Kubota;K. Higashi
镁合金具有低密度的特点，在航空航天等领域具有广阔的应用前景。在未来，大量的机加工切屑将与镁的量增加，因为镁显示出良好的可加工性[1]。然而，由于镁容易氧化，因此难以从加工的切屑再次生产镁材料。回收或消除切屑的方法有重熔切屑、砂烧切屑等，但这些方法成本较高。因此，需要开发新的加工方法来有效地回收机加工的切屑。最近证明[2]，由机加工碎片加工的AZgl镁合金挤压件显示出约320-410 MPa的高极限拉伸强度和室温下约5-12%的大断裂伸长率的良好组合。挤压件的高强度和高塑性的良好结合归因于晶粒细化。由于晶粒细化导致小晶粒尺寸，因此由机加工切屑加工的挤压件预期显示出超塑性行为。镁合金的超塑性已有文献报道[3-6]。例如，由Cr和/3两个细晶相组成的Mg-Li合金层压板在应变速率为10-3 s-1和473 K时显示出455%的伸长率[3]。此外，通过快速凝固技术处理的AZ 91镁合金在573 K下显示出1480%的大伸长率[5]。本文采用机加工切屑加工AZgl镁合金挤压件，并在573 K高温下测试挤压件的力学性能，以研究机加工切屑加工挤压件的超塑性行为。通过在车床上机加工商业AZ 91合金铸锭来制备切屑。AZ 91机加工切屑如图1所示。从机加工切屑制造挤压件的工艺与先前工作中使用的工艺相同[2]。在573 K和390 MPa的压力下在空气中烧结加工的芯片。烧结的坯料被
Magnesium alloys have potential for use of as structural component in aerospace and outerspace applications because of their low density. In the future a large amount of machined chips will be produced with an increased amount of magnesium because magnesium shows good machinability [1]. However, it is difficult to produce magnesium materials again from the machined chips, because magnesium is readily oxidized. The methods for reclamation or elimination of the machined chips are remelting the machined chips, burning them with sands and so on, but these methods involve high cost. It is therefore desirable to develop new processing methods for efficient reclamation of the machined chips. It was recently demonstrated [2] that AZgl magnesium alloy extrusions processed from the machined chips showed a good combination of high ultimate tensile strength of about 320-410 MPa and large elongations to failure of about 5-12% at room temperature. The good combination of high strength and high ductility of the extrusions are attributed to grain refinement. Since grain refinement results in small grain size, the extrusions processed from the machined chips are expected to show superplastic behaviour. Superplasticity of magnesium alloys has been reported in some works [3-6]. For example, Mg-Li alloy laminate composed of two fine-grained phases of cr and/3 showed 455% elongation at strain rate 10-3 s-1 and 473 K [3]. Also, AZ91 magnesium alloy processed by the rapid solidification technique showed a large elongation of 1480% at 573 K [5]. In this work an AZgl magnesium alloy extrusion was processed from machined chips, and the mechanical properties of the extrusion were examined at the elevated temperature of 573 K to investigate superplastic behaviour of the extrusion processed from the machined chips.Chips were prepared by machining a commercial AZ91 alloy cast ingot in a lathe. The AZ91 machined chips are shown in Fig. 1. The processing to fabricate the extrusion from the machined chips was the same as that used in the previous work [2]. The machined chips were sintered at 573 K with a pressure of 390 MPa in air. The sintered billet was