低溫大載荷沖擊下純銅和工業(yè)純鐵的微觀組織與性能研究
發(fā)布時(shí)間：2018-11-09 07:28
【摘要】：與傳統(tǒng)粗晶材料相比,塊體超細(xì)晶(UFG)材料由于具有更加出色的力學(xué)性能和物理性能,成為當(dāng)前材料領(lǐng)域的研究熱點(diǎn)之一。強(qiáng)烈塑性變形(SPD)由于具有良好的晶粒細(xì)化能力,成為當(dāng)前塊體超細(xì)晶材料制備最常用的方法之一。近些年來,一些低溫強(qiáng)烈塑性變形技術(shù)如低溫軋制、低溫多向鍛造、低溫高壓扭轉(zhuǎn)、低溫等通道轉(zhuǎn)角擠壓等成功應(yīng)用于塊體超細(xì)晶材料的制備。與中高溫強(qiáng)烈塑性變形相比,低溫能夠有效抑制動(dòng)態(tài)回復(fù)過程,促進(jìn)材料內(nèi)部位錯(cuò)的有效積累,誘導(dǎo)機(jī)械孿晶的產(chǎn)生,從而提高晶粒細(xì)化的效率,在較低的應(yīng)變量下得到超細(xì)晶組織。低溫大載荷沖擊變形是一種潛在的用來制備塊體超細(xì)晶材料的新方法。與常見的強(qiáng)烈塑性變形方法相比,工藝簡(jiǎn)單、無需特殊的設(shè)備,有望制備大尺寸的塊體超細(xì)晶材料,具有良好的工業(yè)應(yīng)用前景。但目前關(guān)于低溫大載荷沖擊變形制備塊體超細(xì)晶材料的研究還十分有限。因此,系統(tǒng)的開展塊體金屬材料在低溫大載荷沖擊下的微觀結(jié)構(gòu)演變與性能研究十分有意義。本文利用金相分析、TEM、XRD、顯微硬度、極化曲線等表征手段系統(tǒng)研究了具有FCC結(jié)構(gòu)純銅和具有BCC結(jié)構(gòu)的工業(yè)純鐵兩種金屬材料在低溫大載荷沖擊變形后的微觀組織演變和腐蝕性能以及隨后退火處理對(duì)微觀組織結(jié)構(gòu)和性能的影響。主要研究成果如下：(1)開展純銅低溫大載荷沖擊變形實(shí)驗(yàn),并成功制備出具有板條狀結(jié)構(gòu)的塊體超細(xì)晶純銅材料。當(dāng)應(yīng)變量為2.21時(shí),從橫截面觀察晶粒為等軸狀,尺寸為150-450 nm；從縱截面觀察為板條狀,寬度為30-220nm。微觀組織研究表明,純銅低溫大載荷沖擊晶粒細(xì)化是位錯(cuò)胞演變機(jī)制、動(dòng)態(tài)再結(jié)晶機(jī)制和孿晶細(xì)化機(jī)制三者協(xié)同作用的結(jié)果；(2)經(jīng)過190℃退火60min后,純銅發(fā)生再結(jié)晶,高密度位錯(cuò)消失,晶界清晰平直,晶粒在橫截面上仍為等軸狀,尺寸變?yōu)?00-450 nm；縱截面上仍為板條狀,寬度為70-100nm,此外縱截面上還觀察到大量的退火納米孿晶,孿晶的寬度為10～100 nm；(3)經(jīng)過低溫大載荷沖擊后,純銅在0.5 M NaCl溶液中的腐蝕速率降低；經(jīng)過190℃退火60 min后,試樣的腐蝕速率進(jìn)一步降低；(4)開展工業(yè)純鐵低溫大載荷沖擊變形實(shí)驗(yàn),并成功制備出具有板條狀結(jié)構(gòu)的塊體超細(xì)晶工業(yè)純鐵材料。當(dāng)應(yīng)變量為2.21時(shí),從橫截面觀察晶粒為等軸狀,尺寸為100-300nm；從縱截面觀察為板條狀,寬度為100-350nm。微觀組織研究表明,工業(yè)純鐵低溫大載荷沖擊晶粒細(xì)化主要是由晶粒破碎機(jī)制和位錯(cuò)胞細(xì)化機(jī)制協(xié)同作用來完成的。此外,滲碳體的存在也對(duì)工業(yè)純鐵的晶粒細(xì)化起到一定的促進(jìn)作用；(5)經(jīng)過500℃退火60 min以后,工業(yè)純鐵內(nèi)部位錯(cuò)密度明顯降低,晶粒輪廓清晰,晶粒在橫截面上仍為等軸狀,尺寸變?yōu)?20-310nm；縱截面上仍為板條狀,寬度變?yōu)?0～350nm。與純銅不同的是,退火處理后沒有觀察到退火孿晶組織；(6)經(jīng)過低溫大載荷沖擊后,工業(yè)純鐵在0.5 M NaCl溶液中的腐蝕速率降低,鈍化電流減小,鈍化區(qū)間變寬,鈍化能力得到明顯改善；經(jīng)過500℃退火60 min后,雖然腐蝕速率增大,但鈍化區(qū)間進(jìn)一步增加,鈍化電流更加平穩(wěn),說明退火處理后工業(yè)純鐵的鈍化能力得到進(jìn)一步改善,鈍化膜更加穩(wěn)定。
[Abstract]:Compared with the traditional coarse-crystal material, the bulk ultra-fine crystal (UFG) material has become one of the hot spots in the current material field due to its excellent mechanical properties and physical properties. The strong plastic deformation (SPD) is one of the most common methods for preparing the ultra-fine crystal material of the present block due to its good grain refining ability. In recent years, some low-temperature strong plastic deformation techniques such as low-temperature rolling, low-temperature multi-way forging, low-temperature high-pressure torsion, low-temperature equal-channel corner extrusion and the like are successfully applied to the preparation of bulk superfine crystal materials. Compared with the high-temperature and strong plastic deformation, the low-temperature can effectively inhibit the dynamic recovery process, promote the effective accumulation of the internal dislocation of the material, and induce the generation of the mechanical columnar crystal, thereby improving the grain refining efficiency, and obtaining the superfine crystal tissue at a lower corresponding variable. The low-temperature and large-load impact deformation is a potential new method for preparing the bulk ultra-fine crystal material. Compared with the common strong plastic deformation method, the method has the advantages of simple process, no need of special equipment, and is expected to prepare the bulk superfine crystal material with large size and has good industrial application prospect. However, the research on the preparation of bulk ultra-fine crystal material with low-temperature and large-load impact deformation is very limited. Therefore, the microstructure evolution and performance of the bulk metallic material of the system under the impact of low temperature and large load are of great significance. In this paper, gold phase analysis, TEM, XRD and microhardness were used. The microstructure and corrosion properties of pure copper with FCC structure and the industrial pure iron with BCC structure and the effect of subsequent annealing on the microstructure and properties of the microstructure were studied by means of polarization curve and other characterization methods. The main research results are as follows: (1) the experiment of low-temperature and large-load impact deformation of pure copper is carried out, and the bulk ultra-fine crystal pure copper material with the plate-like structure is successfully prepared. When the variable is 2.21, the grain is equiaxed from the cross-section, the size is 150-450 nm, and the width is 30-220nm from the longitudinal section. The microstructure of pure copper shows that the grain refinement is the result of the synergistic effect of the dislocation cell evolution mechanism, the dynamic recrystallization mechanism and the crystal grain refining mechanism. (2) After annealing for 60min at 190.degree. C., the recrystallization of the pure copper occurs, the high-density dislocation disappears, the grain boundary is clear and straight, the crystal grains are still equiaxed in the cross section, the size is changed to 200-450 nm, the longitudinal section is still a strip-shaped, the width is 70-100nm, and a large amount of the annealed nanocrystalline is also observed on the longitudinal section, and the width of the columnar crystal is 10-100 nm; and (3) after the low-temperature large-load impact, The corrosion rate of pure copper in 0.5M NaCl solution is reduced; after annealing for 60 min at 190.degree. C., the corrosion rate of the sample is further reduced; and (4) industrial pure iron low-temperature large-load impact deformation experiment is carried out, and the bulk ultra-fine crystal industrial pure iron material with the plate-like structure is successfully prepared. When the variable is 2.21, the grain is equiaxed from the cross-section, the size is 100-300nm, and the width is 100-350nm from the longitudinal section. The micro-structure research shows that the grain refinement of the low-temperature and large-load impact of the industrial pure iron is mainly accomplished by the synergistic effect of the grain breaking mechanism and the dislocation cell refining mechanism. In addition, the presence of the cementite has a certain catalytic effect on the grain refinement of the industrial pure iron; (5) after annealing at 500 DEG C for 60 minutes, the dislocation density of the industrial pure iron is obviously reduced, the grain outline is clear, and the grains are still equiaxed in the cross section, and the size thereof is 120-310nm; the longitudinal section is still strip-shaped, and the width thereof is 80-350nm. and after the low-temperature and large-load impact, the corrosion rate of the industrial pure iron in the solution of 0.5 M NaCl is reduced, the passivation current is reduced, the passivation interval is widened, and the passivation capacity is obviously improved; After annealing at 500 鈩，
本文編號(hào)：2319749
[Abstract]:Compared with the traditional coarse-crystal material, the bulk ultra-fine crystal (UFG) material has become one of the hot spots in the current material field due to its excellent mechanical properties and physical properties. The strong plastic deformation (SPD) is one of the most common methods for preparing the ultra-fine crystal material of the present block due to its good grain refining ability. In recent years, some low-temperature strong plastic deformation techniques such as low-temperature rolling, low-temperature multi-way forging, low-temperature high-pressure torsion, low-temperature equal-channel corner extrusion and the like are successfully applied to the preparation of bulk superfine crystal materials. Compared with the high-temperature and strong plastic deformation, the low-temperature can effectively inhibit the dynamic recovery process, promote the effective accumulation of the internal dislocation of the material, and induce the generation of the mechanical columnar crystal, thereby improving the grain refining efficiency, and obtaining the superfine crystal tissue at a lower corresponding variable. The low-temperature and large-load impact deformation is a potential new method for preparing the bulk ultra-fine crystal material. Compared with the common strong plastic deformation method, the method has the advantages of simple process, no need of special equipment, and is expected to prepare the bulk superfine crystal material with large size and has good industrial application prospect. However, the research on the preparation of bulk ultra-fine crystal material with low-temperature and large-load impact deformation is very limited. Therefore, the microstructure evolution and performance of the bulk metallic material of the system under the impact of low temperature and large load are of great significance. In this paper, gold phase analysis, TEM, XRD and microhardness were used. The microstructure and corrosion properties of pure copper with FCC structure and the industrial pure iron with BCC structure and the effect of subsequent annealing on the microstructure and properties of the microstructure were studied by means of polarization curve and other characterization methods. The main research results are as follows: (1) the experiment of low-temperature and large-load impact deformation of pure copper is carried out, and the bulk ultra-fine crystal pure copper material with the plate-like structure is successfully prepared. When the variable is 2.21, the grain is equiaxed from the cross-section, the size is 150-450 nm, and the width is 30-220nm from the longitudinal section. The microstructure of pure copper shows that the grain refinement is the result of the synergistic effect of the dislocation cell evolution mechanism, the dynamic recrystallization mechanism and the crystal grain refining mechanism. (2) After annealing for 60min at 190.degree. C., the recrystallization of the pure copper occurs, the high-density dislocation disappears, the grain boundary is clear and straight, the crystal grains are still equiaxed in the cross section, the size is changed to 200-450 nm, the longitudinal section is still a strip-shaped, the width is 70-100nm, and a large amount of the annealed nanocrystalline is also observed on the longitudinal section, and the width of the columnar crystal is 10-100 nm; and (3) after the low-temperature large-load impact, The corrosion rate of pure copper in 0.5M NaCl solution is reduced; after annealing for 60 min at 190.degree. C., the corrosion rate of the sample is further reduced; and (4) industrial pure iron low-temperature large-load impact deformation experiment is carried out, and the bulk ultra-fine crystal industrial pure iron material with the plate-like structure is successfully prepared. When the variable is 2.21, the grain is equiaxed from the cross-section, the size is 100-300nm, and the width is 100-350nm from the longitudinal section. The micro-structure research shows that the grain refinement of the low-temperature and large-load impact of the industrial pure iron is mainly accomplished by the synergistic effect of the grain breaking mechanism and the dislocation cell refining mechanism. In addition, the presence of the cementite has a certain catalytic effect on the grain refinement of the industrial pure iron; (5) after annealing at 500 DEG C for 60 minutes, the dislocation density of the industrial pure iron is obviously reduced, the grain outline is clear, and the grains are still equiaxed in the cross section, and the size thereof is 120-310nm; the longitudinal section is still strip-shaped, and the width thereof is 80-350nm. and after the low-temperature and large-load impact, the corrosion rate of the industrial pure iron in the solution of 0.5 M NaCl is reduced, the passivation current is reduced, the passivation interval is widened, and the passivation capacity is obviously improved; After annealing at 500 鈩，
本文編號(hào)：2319749
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