【摘要】：為了研究服役構(gòu)件的蠕變損傷行為,本文采用磁性檢測(cè)法、X射線衍射法以及硬度法等方法來(lái)表征P91鋼在不同蠕變狀態(tài)下的損傷情況。首先對(duì)P91鋼進(jìn)行高溫單軸拉伸試驗(yàn),得到不同溫度下P91鋼的高溫力學(xué)性能。隨后,通過(guò)給定條件下高溫蠕變持久試驗(yàn),得到了所需的蠕變曲線和試樣的斷裂時(shí)間。根據(jù)完整的蠕變曲線,在各蠕變階段選取間斷時(shí)間點(diǎn)進(jìn)行蠕變間斷試驗(yàn),制備不同蠕變狀態(tài)下的損傷試樣。最后利用磁滯回線檢測(cè)、X射線衍射檢測(cè)以及硬度檢測(cè)對(duì)蠕變?cè)嚇拥膿p傷狀態(tài)進(jìn)行參數(shù)化表征,并結(jié)合金相觀察以及斷口組織觀察,進(jìn)一步驗(yàn)證參數(shù)化表征的準(zhǔn)確性。具體的研究?jī)?nèi)容與結(jié)論如下:1)高溫單軸拉伸試驗(yàn)得到P91鋼在620℃和600℃條件下的力學(xué)性能,包括抗拉強(qiáng)度σb、屈服強(qiáng)度σ0.2、彈性模量E以及延伸率δ。通過(guò)蠕變持久試驗(yàn)獲得了 620℃、145 MPa和600℃、175MPa條件下的蠕變曲線和斷裂時(shí)間,并獲得蠕變間斷試驗(yàn)的時(shí)間,進(jìn)而通過(guò)蠕變間斷試驗(yàn)制備損傷試樣。2)磁性檢測(cè)、X射線衍射以及硬度法檢測(cè)的結(jié)果顯示:磁性參數(shù)矯頑力(Hc)、剩磁(Br)以及最大磁導(dǎo)率(μm)隨著蠕變時(shí)間的變化趨勢(shì),半寬高(FWHM)、位錯(cuò)密度(ρ)隨蠕變時(shí)間的變化趨勢(shì),以及硬度值(HV)隨著蠕變時(shí)間的變化趨勢(shì)均呈現(xiàn)先上升后下降的趨勢(shì)。結(jié)合金相以及斷口組織觀察,結(jié)果顯示:上述三種檢測(cè)方法可以較好地表征高溫下的蠕變損傷狀態(tài)。3)通過(guò)對(duì)上述三種測(cè)量結(jié)果的全面分析,結(jié)果表明:磁性檢測(cè)方法中磁性參數(shù)受材料的化學(xué)成分以及結(jié)構(gòu)影響,且測(cè)量簡(jiǎn)單,但在短時(shí)蠕變損傷中,表征參數(shù)對(duì)材料內(nèi)部組織的演化情況不夠敏感;X射線衍射方法較為成熟,但其適用于應(yīng)力急劇變化且范圍較小時(shí),且局限于測(cè)量構(gòu)件表面的損傷狀態(tài),并對(duì)人體健康具有一定的危害;硬度檢測(cè)法簡(jiǎn)單易行,但硬度參量是反映材料內(nèi)部組織演化以及材料性能的間接參量,一般作為參考指標(biāo)來(lái)使用。綜上所述,本文采用的磁性檢測(cè)法、X射線衍射法以及硬度法均實(shí)現(xiàn)了對(duì)P91鋼不同蠕變狀態(tài)的參數(shù)化表征,且每種方法各有優(yōu)缺點(diǎn)。其中,磁性檢測(cè)法能夠更直接地反映P91鋼在不同蠕變階段的內(nèi)部組織演化情況,以便進(jìn)一步表征P91鋼在蠕變過(guò)程中材料內(nèi)部的損傷情況。
[Abstract]:In order to study the creep damage behavior of service members, magnetic detection method, X-ray diffraction method and hardness method are used to characterize the damage of P91 steel under different creep states. First, the high temperature uniaxial tensile test of P91 steel was carried out, and the mechanical properties of P91 steel at different temperatures were obtained. Then, the creep curve and fracture time of the specimen are obtained by the creep rupture test at high temperature under a given condition. According to the complete creep curve, the discontinuous creep test was carried out at different time points in the creep stage, and the damage samples were prepared under different creep states. Finally, the damage state of creep specimens was parameterized by hysteresis loop detection, X-ray diffraction and hardness measurement. The accuracy of parameterized characterization was further verified by metallographic observation and fracture microstructure observation. The specific research contents and conclusions are as follows: 1) the mechanical properties of P91 steel at 620 鈩，

本文編號(hào)：2268737