本文選題：無鉛黃銅 + 電脈沖處理�。� 參考：《北京科技大學(xué)》2015年博士論文

【摘要】：本文利用電脈沖熔體處理和變質(zhì)處理技術(shù)對(duì)鉛黃銅鑄態(tài)組織、鑄造性能及切削性能的影響進(jìn)行對(duì)比研究,確定電脈沖熔體處理可以有效細(xì)化鉛黃銅微觀組織結(jié)構(gòu),進(jìn)而改善其切削性能。在此研究基礎(chǔ)上,以電脈沖熔體處理技術(shù)為強(qiáng)化手段,以硅代替鉛并結(jié)合有效合金化理論和適當(dāng)?shù)臒崽幚砉に囂剿饕环N具有易切削、耐磨耐蝕性能的(β+γ)雙相硅黃銅合金。通過對(duì)該合金液固轉(zhuǎn)變和固態(tài)相變特點(diǎn)的研究,建立了(p+γ)雙相硅黃銅合金熔體中電脈沖“孕育”團(tuán)簇的機(jī)理模型,并在實(shí)驗(yàn)上驗(yàn)證了模型的準(zhǔn)確性。 研究結(jié)果表明,適當(dāng)參數(shù)的電脈沖作用于(β+γ)雙相硅黃銅合金熔體能夠細(xì)化其凝固組織,增加Si在p相基體中的固溶度,減少合金凝固組織中丫相的尺寸和數(shù)量,改善合金中γ相的偏析程度,進(jìn)而提高了該合金的切削、耐磨及耐蝕性能。當(dāng)脈沖電壓為1000V,處理時(shí)間為30s,脈沖頻率為8Hz時(shí),合金凝固組織中γ相呈點(diǎn)狀均勻彌散分布于p相基體中,γ相尺寸由44μm減小到22μm,γ相體積份數(shù)由66.23%減少到49.94%,基體顯微硬度由336.03HV升高到399.62HV,抗拉強(qiáng)度由250MPa提升至380MPa。 電脈沖處理后(β+γ)雙相硅黃銅合金熔體結(jié)構(gòu)模型認(rèn)為,電脈沖熔體處理增強(qiáng)了合金熔體中游離的Zn原子與富Cu的Cu-Zn原子團(tuán)簇間的作用,增加了合金熔體中富Cu的Cu-Zn原子團(tuán)簇?cái)?shù)量,且該原子團(tuán)簇尺度向小尺度方向發(fā)展。通過綜合熱分析、熱膨脹分析、丫相尺寸及其體積份數(shù)的變化、基體顯微硬度等實(shí)驗(yàn)對(duì)該模型的正確性進(jìn)行間接地驗(yàn)證。同時(shí),以此模型為基礎(chǔ),分析了電脈沖處理細(xì)化(β+γ)雙相硅黃銅合金凝固組織、改善合金偏析、提高合金耐磨和耐蝕性能的作用機(jī)制。 在(β+γ)雙相硅黃銅合金電脈沖熔體處理工藝研究的基礎(chǔ)上,對(duì)其熱處理工藝進(jìn)行研究,為電脈沖熔體處理技術(shù)的實(shí)際應(yīng)用奠定堅(jiān)實(shí)的試驗(yàn)基礎(chǔ)。研究表明：在經(jīng)過最佳脈沖處理參數(shù)(脈沖電壓為1000V,處理時(shí)間為30s,脈沖頻率為8Hz)處理后的(β+γ)雙相硅黃銅合金再經(jīng)600℃、4h固溶、水淬,250℃、6h人工時(shí)效后,合金的基體顯微硬度僅為未處理時(shí)的75%。采用此熱處理工藝既能消除電脈沖細(xì)晶及β相固溶強(qiáng)化所導(dǎo)致的基體硬度升高,同時(shí)亦可實(shí)現(xiàn)對(duì)γ相的有效變質(zhì),提高其切削性能,為無鉛易切削硅黃銅的新技術(shù)開發(fā)提供理論基礎(chǔ)。
[Abstract]:In this paper, the effects of electropulse melt treatment and modification on the cast structure, casting properties and cutting properties of lead brass were compared and studied. It was determined that the electric pulse melt treatment could refine the microstructure of lead brass effectively. Then the cutting performance is improved. On the basis of this study, a kind of (尾 緯) duplex silicon brass alloy with easy cutting and wear resistance and corrosion resistance was explored by means of electric pulse melt treatment technology, silicon instead of lead and effective alloying theory and proper heat treatment technology. Based on the study of the liquid-solid and solid phase transition characteristics of the alloy, the mechanism model of electric pulse "inoculation" in the melt of p 緯) silicon brass alloy has been established, and the accuracy of the model has been verified experimentally. The results show that the effect of electrical pulse with appropriate parameters on the solidification structure of (尾 緯) two-phase silicon brass alloy can refine the solidification structure, increase the solid solubility of Si in p-phase matrix, and reduce the size and quantity of Ya phase in solidified microstructure of the alloy. The segregation degree of 緯 phase in the alloy was improved, and the cutting, wear resistance and corrosion resistance of the alloy were improved. When the pulse voltage is 1000V, the processing time is 30s and the pulse frequency is 8Hz, The 緯 phase in solidified microstructure is distributed uniformly in p phase matrix, the size of 緯 phase decreases from 44 渭 m to 22 渭 m, the volume fraction of 緯 phase decreases from 66.23% to 49.94, the microhardness of matrix increases from 336.03HV to 399.62 HVand the tensile strength increases from 250MPa to 380 MPA. The (尾 緯) dual phase silicon brass alloy melt structure model shows that the electric pulse melt treatment enhances the interaction between the free Zn atom in the alloy melt and the Cu rich Cu-Zn cluster. The number of Cu rich Cu-Zn cluster in the alloy melt was increased and the scale of the cluster developed to a small scale. The correctness of the model was indirectly verified by comprehensive thermal analysis, thermal expansion analysis, changes of phase size and volume fraction, and matrix microhardness. At the same time, based on the model, the mechanism of electric pulse treatment for refining (尾 緯) double phase silicon brass alloy solidified microstructure, improving alloy segregation, improving the wear resistance and corrosion resistance of the alloy was analyzed. Based on the study of (尾 緯) duplex silicon brass alloy electric pulse melt treatment technology, the heat treatment process is studied, which lays a solid experimental foundation for the practical application of electric pulse melt treatment technology. The results show that after the best pulse treatment parameters (pulse voltage 1000V, treatment time 30s, pulse frequency 8Hz), the (尾 緯) dual phase silicon brass alloy is dissolved at 600 鈩，

本文編號(hào)：1965448