本文選題：鐵磁性材料　切入點(diǎn)：矯頑力　出處：《沈陽工業(yè)大學(xué)》2017年碩士論文

【摘要】：隨著我國油氣管道的大規(guī)模運(yùn)用,管道網(wǎng)絡(luò)的運(yùn)行安全問題更加的值得關(guān)注。目前在役油氣管道通常選用低碳鋼等鐵磁性材料制作,管道在長期實(shí)際工程運(yùn)行時可不避免會產(chǎn)生應(yīng)力集中區(qū)域,應(yīng)力集中區(qū)域的存在會導(dǎo)致破裂及腐蝕等管道缺陷,產(chǎn)生不良后果并造成巨大經(jīng)濟(jì)損失和生命財(cái)產(chǎn)安全。對在役管道重要防護(hù)區(qū)域定期檢測,是減少應(yīng)力導(dǎo)致安全事故的重要手段。應(yīng)力會對磁性材料的特性參數(shù)造成一定的影響變化,而應(yīng)力與材料矯頑力間的關(guān)系相對簡單易于檢測,利用矯頑力數(shù)值對管道所受應(yīng)力進(jìn)行評估,對管道應(yīng)力檢測具有重要意義。本文對應(yīng)力對鐵磁性材料矯頑力的影響進(jìn)行了深入的分析;應(yīng)力的施加會對磁化過程中不可逆磁化階段形成了阻礙,而矯頑力的形成與這一階段有直接關(guān)系,因此應(yīng)力施加會對鐵磁性材料產(chǎn)生影響。提出了一種基于矯頑力的管道應(yīng)力檢測技術(shù),構(gòu)建了基于矯頑力的管道應(yīng)力檢測硬件和軟件系統(tǒng)。該系統(tǒng)采用U型探頭進(jìn)行檢測,探頭置于被測工件表面,利用低頻正弦信號經(jīng)過功率放大電路接入激勵線圈將U型探頭與被測工件進(jìn)行交流磁化,感應(yīng)信號通過感應(yīng)信號調(diào)理電路進(jìn)行處理產(chǎn)生感應(yīng)信號。主控芯片接到脈沖信號后將此刻激勵端電流數(shù)值通過矯頑力采集電路進(jìn)行采集,經(jīng)過計(jì)算得到材料的矯頑力數(shù)值。通過矯頑力數(shù)值的分析可以間接得到材料受到應(yīng)力大小,從而進(jìn)行應(yīng)力評估。實(shí)驗(yàn)中,選取不同頻率對U型傳感器的感應(yīng)信號進(jìn)行分析,確定磁化最佳頻率,并進(jìn)行了系統(tǒng)裝置的準(zhǔn)確性及穩(wěn)定性實(shí)驗(yàn),選用Q235鋼材作為工件材料在彈性形變階段進(jìn)行在線拉力實(shí)驗(yàn),證明應(yīng)力與矯頑力存在線性關(guān)系,后依次選擇管道所用的X70管道低碳、X80管道低碳鋼作為材料工件進(jìn)行在彈性形變階段的拉力實(shí)驗(yàn),對不同厚度的不受應(yīng)力的Q235鋼材工件進(jìn)行矯頑力測量。實(shí)驗(yàn)結(jié)果表明:U型探頭在30Hz-50Hz頻率下磁化效果最佳,基于矯頑力的應(yīng)力檢測系統(tǒng)檢測Q235等材料在6mm厚度范圍內(nèi)的系統(tǒng)誤差范圍為±2%;測量精度為0.1A/m;標(biāo)準(zhǔn)差為1.92。鐵磁性材料所受到的應(yīng)力與測量得到的矯頑力數(shù)值呈現(xiàn)線性關(guān)系,不同管道材料對矯頑力與應(yīng)力的變化率有一定影響,但不影響應(yīng)力與矯頑力線性關(guān)系。在12mm內(nèi)同一材料不同厚度不會對系統(tǒng)裝置檢測的矯頑力數(shù)值造成影響。
[Abstract]:With the large-scale use of oil and gas pipelines in China, the safety of pipeline network operation is more worthy of attention. At present, in service oil and gas pipelines are usually made of low carbon steel and other ferromagnetic materials. In the long run of actual engineering, the stress concentration area can not be avoided, and the existence of stress concentration area will lead to pipeline defects, such as rupture and corrosion, etc. Causing adverse consequences and causing huge economic losses and safety of life and property. Regular inspection of important protected areas of existing pipelines, Stress can influence the characteristic parameters of magnetic material, and the relationship between stress and coercivity is relatively simple and easy to detect. In this paper, the effect of stress on coercivity of ferromagnetic materials is analyzed. The application of stress will hinder the irreversible magnetization stage in the process of magnetization, and the formation of coercivity is directly related to this stage. Therefore, stress exertion will have an effect on ferromagnetic material. A coercivity based pipeline stress detection technique is proposed, and a hardware and software system of pipeline stress detection based on coercivity is constructed. The system uses U-shaped probe to detect the stress. The probe is placed on the surface of the workpiece being tested, and the U-shaped probe and the workpiece are magnetized AC by using the low frequency sinusoidal signal through the power amplifier circuit to connect the exciting coil. The inductive signal is processed by the induction signal conditioning circuit to produce the inductive signal. After the main control chip receives the pulse signal, the current value of the exciting end is collected through the coercivity acquisition circuit. The coercivity value of the material can be calculated by the analysis of the coercivity value. The stress magnitude of the material can be indirectly obtained by the analysis of the coercivity value, and the stress can be evaluated. In the experiment, the inductive signals of the U-shaped sensor are analyzed with different frequencies. The optimum frequency of magnetization is determined, and the accuracy and stability of the system are tested. The on-line tension test of Q235 steel as workpiece material in elastic deformation stage proves that there is a linear relationship between stress and coercivity. The X70 low carbon steel used in the X70 pipeline was selected as the material workpiece to carry out the tensile test at the elastic deformation stage. The coercivity measurement of different thickness unstressed Q235 steel workpieces is carried out. The experimental results show that the #number0# U probe has the best magnetization effect at 30Hz-50Hz frequency. The stress detection system based on coercivity has a linear relationship between the stress of ferromagnetic materials and the measured coercivity. The systematic error range of Q235 and other materials in the 6mm thickness range is 鹵2, the measuring accuracy is 0.1 A / m, and the standard deviation is 1.92. The change rate of coercivity and stress is influenced by different pipe materials, but the linear relationship between stress and coercivity is not affected. Different thickness of the same material in 12mm will not affect the coercivity value measured by the system device.
【學(xué)位授予單位】：沈陽工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TE973.6

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本文編號：1696148