熔体混合处理及过热变质对ZA27合金组织和性能的影响

【作者】 赵红乐；

【导师】 王荣峰；

【作者基本信息】 太原科技大学 ， 材料加工工程， 2012， 硕士

【摘要】 锌铝系合金是目前应用较为广泛的新型金属材料。锌铝合金具有很多优点，强度高、硬度大、耐磨性能优良、制造成本低廉。同时，锌铝合金还具有熔点低，耗能少，成型方便，适用于多种铸造方法的特点。在锌铝合金中，以ZA27合金性能最为优异，但是ZA27合金也有锌铝合金所共有的一些缺点，如塑韧性差、工作温度低、耐蚀性差等。本文分别通过熔体混合和过热变质两种方法对ZA27合金进行处理。所有实验均按正交设计方法来安排实验，并对实验结果进行分析，确定了实验过程中各影响因素的强弱以及较优的组合方法。1、采用正交实验设计方法研究了熔体混合处理对ZA27合金组织与性能的影响，确定高温熔体和低温熔体的最优组合。1）熔体混合处理可以明显提高ZA27合金的力学性能。当高温熔体温度为720℃，低温熔体温度为500℃时，ZA27合金综合力学性能最好。处理后的合金硬度122.5HB，比未处理的提高10.66％；冲击韧性为18.49j/cm~2，比未处理的提高63.48％。2）熔体混合处理能够明显细化ZA27合金铸态组织。适合的处理方法可以使铸态组织由树枝状向花瓣状转变。3）方差分析表明：影响熔体混合处理的因素强弱顺序为高温熔体温度、高低温熔体交互作用、低温熔体温度。高温熔体温度影响非常显著，高低温熔体交互作用对实验有一定影响,低温熔体温度主要通过和高温熔体的作用影响实验结果。2采用正交实验设计方法研究了过热变质对ZA27合金组织与性能的影响，确定了变质剂用量和过热温度以及过热保温时间对合金性能的影响强弱，并确定较优的实验组合方案。1）过热变质可以明显提高ZA27合金的力学性能。当稀土用量为0.2％、过热温度为780℃、过热保温时间为10min时合金性能最佳。此时合金硬度为110.5HB，冲击韧性为20.5j/cm~2；冲击韧性比未处理合金提高81.26％。2）过热变质能够明显细化ZA27合金铸态组织。适合的处理方法可以使合金铸态组织有边缘球化的趋势，同时能够明显细化合金。3）方差分析表明：稀土用量对ZA27合金的硬度影响非常显著，过热温度的影响也比较显著，而过热保温时间的长短影响一般。过热温度对ZA27合金的韧性有显著的影响，稀土用量也有一定的影响，而过热保温时间的长短无明显影响。更多还原

【Abstract】 Zn-Al alloy is widely used as a new type of metal material. Zn-Al alloyhas a lot of advantages, such as high strength, high hardness, excellent wearresistance performance, low production cost.Meanwhile, Zn-Al alloy also hasthe characteristics of low melting point, less energy consumption, formingconvenient, applicable for various casting method. In Zn-Al alloy, ZA27alloyhas the most excellent performance,but ZA27alloy also has somedisadvantages like other Zn-Al alloy, such as plastic toughness is bad, thework temperature is low, corrosion resistance is bad etc.In this paper, the meltmixing and overheating metamorphic were used to process the ZA27alloy.Through the orthogonal design method arrange all experiment, theexperimental results were analyzed and identify the intensitied of eachaffecting factor and the best combination method.1.The effect of melt mixing treatment on the microstructures andmechanical properties of ZA27alloy was studied by the method of orthogonaltest and determine the optimum combination of high temperature melt andlow-temperature melt.1). Mixing melt treatment can obviously improve the mechanicalproperties of ZA27alloy, refining cast structure of alloy. When the temperatureof high temperature melt is720℃, the temperature of low temperature melt is500℃, ZA27alloy comprehensive mechanical performance is best. Thehardness of alloy with treatment is122.5HB,increased10.66%than the alloywithout treatment.2). Mixing melt treatment can obviously refine cast structure of alloy ofZA27alloy, Appropriate treatment can change cast microstructures from thedendritic to the petals shape.3).Variance analysis shows: Influence factors of the treatment are thetemperature of high temperature melt,interaction of high and low melttemperature. The temperature of high temperature melt has a remarkableremarkable effect; interaction of high and low temperature have some influence;low temperature melt mainly through the impact of high temperature melt to influence the result of the experiment.2.The effect of overheating metamorphic on the microstructures andmechanical properties of ZA27alloy was studied by the method of orthogonaltest. Influencing factors in the experiment are the amount of metamorphic,overheating temperature and over-temperature holding time, determine thefactors affect the strength of the alloys, and to determine the optimumexperimental combinations.1).Overheating metamorphic can obviously improve the mechanicalproperties of ZA27alloy. When the dosage of rare earth is0.2%, overheatingtemperature is780℃,when overheating holding time is10min, the alloy hasthe best performance. At this time the hardness of alloy is110.5HB, impacttoughness is20.5j/cm~2; Impact toughness increased81.26%than the alloywithout treatment.2).Overheating metamorphic can obviously refine cast structure of ZA27alloy. Appropriate treatment can make the edge of cast microstructures to beglobularity and refine cast structure of alloy.3).Variance analysis shows: The influence of rare earth amount on thehardness of ZA27alloy is very important,and the overheating temperature isimportant too, but the influence of holding time is not significant. The influenceof overheating temperature on the toughness of ZA27alloy is verysignificant,and the amount of rare earth is significant, while the influence ofholding time is not significant.更多还原