【摘要】：半固態(tài)金屬同時具有流變特性和觸變特性,半固態(tài)加工技術(shù)作為一種先進(jìn)的金屬成形方法,集固態(tài)金屬加工成形的力學(xué)性能好和液態(tài)金屬加工的成形性好等優(yōu)點(diǎn)于一體。為了研究半固態(tài)金屬單向壓縮的組織演變規(guī)律和變形特性,本文對半固態(tài)ZCuSn10銅合金進(jìn)行了單向壓縮實(shí)驗(yàn)。首先采用應(yīng)變誘導(dǎo)熔化激活法(SIMA)制備半固態(tài)坯料,將半固態(tài)坯料加工成一定尺寸的圓柱形試樣,再在Gleeble-1500試驗(yàn)機(jī)上進(jìn)行單向壓縮實(shí)驗(yàn),分析了不同壓縮參數(shù)下的顯微組織的演變、變形特性和單向壓縮過程中的變形機(jī)制,建立了半固態(tài)ZCuSn10銅合金的本構(gòu)模型。主要研究結(jié)果如下：在Gleeble-1500熱模擬試驗(yàn)機(jī)上對半固態(tài)ZCuSn10銅合金試樣進(jìn)行了單向壓縮試驗(yàn),得到其變形的真應(yīng)力-應(yīng)變曲線。通過在不同應(yīng)變量、不同溫度、不同應(yīng)變速率的單向壓縮實(shí)驗(yàn),證明ZCuSn10銅合金的半固態(tài)壓縮流變應(yīng)力與溫度、應(yīng)變速率以及應(yīng)變量具有相關(guān)性,在此基礎(chǔ)上通過回歸分析建立了半固態(tài)ZCuSn10銅合金變形的本構(gòu)模型。此外,對半固態(tài)ZCuSn10銅合金和常規(guī)鑄造ZCuSn10銅合金壓縮變形時的研究表明：應(yīng)變量、變形溫度和應(yīng)變速率對流變應(yīng)力大小、顯微組織變化和液相分布有顯著影響,即相同變形條件下,半固態(tài)ZCuSn10銅合金的流變應(yīng)力是常規(guī)鑄造ZCuSn10銅合金的一半左右；隨著應(yīng)變量的增加,半固態(tài)ZCuSn10銅合金固液分離現(xiàn)象更加嚴(yán)重,自由變形區(qū)液相顯著增加,應(yīng)變量對峰值應(yīng)力影響較�。浑S著應(yīng)變速率的增加,峰值應(yīng)力增加；隨著溫度的升高,自由變形區(qū)液相增加,峰值應(yīng)力增加。半固態(tài)ZCuSn10銅合金在單向壓縮過程中的變形機(jī)制包括：液相流動,即液相從等靜壓應(yīng)力較大的晶界處流向等靜壓應(yīng)力較小的晶界處,等靜壓應(yīng)力較大的晶界一般垂直于壓縮軸,等靜壓應(yīng)力較小的晶界一般平行于壓縮軸；固相晶界滑移轉(zhuǎn)動,伴隨液相流動變形的還有固液相混合流動；互相接觸的固相晶粒間在壓應(yīng)力作用下的塑性變形。
[Abstract]:Semi-solid metal has both rheological and thixotropic properties. As an advanced metal forming method, semi-solid metal processing technology has the advantages of good mechanical properties of solid metal processing and good formability of liquid metal processing. In order to study the microstructure evolution and deformation characteristics of semisolid metal under unidirectional compression, unidirectional compression experiments were carried out on semisolid ZCuSn10 copper alloy. First, semisolid billets were prepared by strain induced melting activation method (SIMA). The semisolid billets were processed into cylindrical specimens of a certain size, and then unidirectional compression experiments were carried out on a Gleeble-1500 tester to analyze the evolution of microstructure under different compression parameters. The constitutive model of semisolid ZCuSn10 copper alloy was established by deformation characteristics and deformation mechanism during unidirectional compression. The main results are as follows: unidirectional compression tests were carried out on semi-solid ZCuSn10 copper alloy samples on Gleeble-1500 thermal simulation machine, and the true stress-strain curves of the samples were obtained. Through unidirectional compression experiments at different strain, different temperature and different strain rate, it is proved that the rheological stress of semisolid compression of ZCuSn10 copper alloy is correlated with temperature, strain rate and strain. On this basis, the constitutive model of semi-solid ZCuSn10 copper alloy deformation was established by regression analysis. In addition, during compression deformation of semisolid ZCuSn10 copper alloy and conventional cast ZCuSn10 copper alloy, it is shown that the strain, deformation temperature and strain rate have significant effects on the flow stress, microstructure change and liquid phase distribution. Under the same deformation condition, the flow stress of semisolid ZCuSn10 copper alloy is about half of that of conventional cast ZCuSn10 copper alloy, and with the increase of strain, the solid-liquid separation phenomenon of semisolid ZCuSn10 copper alloy becomes more serious, and the liquid phase in free deformation zone increases significantly. The strain has little effect on the peak stress; with the increase of strain rate, the peak stress increases; with the increase of temperature, the liquid phase increases and the peak stress increases in the free deformation zone. The deformation mechanism of semisolid ZCuSn10 copper alloy during unidirectional compression includes: liquid phase flow, that is, the liquid phase flows from the grain boundary with high isostatic pressure stress to the grain boundary where the isostatic pressure stress is small, and the grain boundary with higher isostatic pressure stress is generally perpendicular to the compression axis. The grain boundaries with small isostatic compressive stress are generally parallel to the compression axis; the solid grain boundary slips and rotates, accompanied by the solid-liquid mixed flow deformation; and the plastic deformation of the solid grains in contact with each other under the compressive stress.
【學(xué)位授予單位】：昆明理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2015
【分類號】：TG146.11

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本文編號：2205378