流变挤压铸造ZCuSn10Pl铜合金轴套的组织和力学性能研究

发布时间：2018-02-10 00:58

本文关键词： ZCuSn10P1铜合金流变挤压组织工艺参数力学性能　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：铜合金的应用领域广泛,传统液态成形由于其熔点较高,存在模具寿命短、产品能耗大、易氧化、吸气等问题,而铜合金半固态成形则有望降低模具温度、提高模具寿命、降低能耗,提高产品性能,因此,开展铜合金半固态成形技术具有重要的科学意义和使用价值。本文将冷轧-重熔应变诱导熔化激活法的制浆工艺和挤压铸造工艺相结合,提出了一种新的流变挤压铸造工艺。设计内加弹簧和挡料圈的模具进行了流变挤压铸造铜合金轴套实验,在定量浇注、制浆工艺与挤压铸造工艺间的衔接等方面进行了尝试。并以ZCuSn10P1铜合金轴套为研究对象,研究了成形工艺参数对轴套组织和性能的影响规律,本文的主要研究内容及研究结果如下:(1)流变挤压铸造ZCuSn10P1铜合金轴套过程中,沿着充型方向,组织内液相增加,在垂直充型方向上,轴套里外两端的液相比中间组织的液相偏高。随着成形比压增加,轴套组织的均匀性先变好后变差。随着挤压速率提高,轴套组织均匀性提高。在成形比压250MPa、挤压速率15mm/s时,流变挤压铸造ZCuSn10P1铜合金轴套组织最均匀。(2)随着成形比压增加,初生固相平均晶粒尺寸和形状因子先减小后增大;随着挤压速率提高,初生固相平均晶粒尺寸和形状因子逐渐减小。在成形比压250MPa、挤压速率15mm/s时,流变挤压铸造ZCuSn10P1铜合金轴套组织的初生固相平均晶粒尺寸和形状因子最小,分别为83.3μm和1.59。(3)轴套组织越均匀,初生固相颗粒尺寸越小,力学性能越高。随着成形比压增大,轴套的力学性能先增加后减小;随着挤压速率提高,轴套力学性能逐渐提高。在成形比压250MPa、挤压速率15mm/s时,轴套力学性能最好,抗拉强度为371.1MPa,延伸率为8.4%,与液态挤压铸件相比,其抗拉强度、延伸率分别提高了 55.9%、83.3%。(4)流变挤压轴套与常规液态挤压轴套的拉伸断口形貌有较大的差异,液态挤压件为脆性断裂,强度和延伸率都较低。流变挤压铸造铜合金轴套的断口形貌类似,都属于混合型断口,在固相颗粒间液相较多的区域易产生沿晶脆性断裂;在固相颗粒间液相较少的区域,则会同时产生穿晶脆性断裂和韧性断裂。
[Abstract]:Copper alloy is widely used in many fields. Due to its high melting point, short die life, high energy consumption, easy oxidation and inspiratory, semisolid forming of copper alloy is expected to reduce die temperature and improve die life. In order to reduce energy consumption and improve product properties, it is of great scientific significance and practical value to develop semisolid forming technology of copper alloy. In this paper, the pulping process of cold rolling and remelting strain induced melting activation method is combined with squeeze casting process. A new rheological squeeze casting process was proposed. The die with spring and stopper ring was designed to carry out the experiment of rheological squeeze casting copper alloy shaft sleeve, and the casting was carried out quantitatively. The connection between pulping process and squeeze casting process was attempted. The influence of forming process parameters on the structure and properties of ZCuSn10P1 copper alloy shaft sleeve was studied. The main contents and results of this paper are as follows: (1) in the process of rheological squeeze casting ZCuSn10P1 copper alloy sleeve, the liquid phase in the microstructure increases along the filling direction and increases in the vertical filling direction. The liquid phase of the inner and outer ends of the shaft sleeve is higher than that of the intermediate structure. With the increase of the forming pressure, the uniformity of the sleeve structure first improves and then becomes worse. With the increase of the extrusion rate, the uniformity of the sleeve structure increases. When the forming specific pressure is 250 MPA, the extrusion rate is 15 mm / s. The average grain size and shape factor of primary solid phase decreased firstly and then increased with the increase of extrusion rate, and the average grain size and shape factor increased with the increase of extrusion rate. The average grain size and shape factor of primary solid phase decreased gradually. When the forming pressure was 250 MPA and the extrusion rate was 15 mm / s, the average grain size and shape factor of ZCuSn10P1 copper alloy sleeve in rheological squeeze casting was the smallest. The microstructure of the sleeve is 83.3 渭 m and 1.59.93 渭 m, respectively. The smaller the size of the primary solid particles, the higher the mechanical properties. With the increase of the forming pressure, the mechanical properties of the sleeve increase first and then decrease, and with the increasing of extrusion rate, the mechanical properties of the sleeve increase firstly and then decrease with the increase of extrusion rate. The mechanical properties of the shaft sleeve are improved gradually. When the forming pressure is 250 MPA and the extrusion rate is 15 mm / s, the mechanical properties of the sleeve are the best, the tensile strength is 371.1 MPA, the elongation is 8.4%, and the tensile strength is higher than that of the liquid extrusion casting. The tensile fracture morphology of the rheological extrusion sleeve is different from that of the conventional liquid extrusion sleeve, and the liquid extrusion part is brittle fracture. The fracture surface morphology of rheological squeeze casting copper alloy sleeve is similar, which belongs to mixed fracture surface, and it is easy to produce intergranular brittle fracture in the region with more liquid phase between solid particles, while in the region with less liquid phase between solid particles, the fracture surface of the shaft sleeve is similar. Transgranular brittle fracture and ductile fracture will occur simultaneously.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG249.2

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