【摘要】：近年來(lái),在極低溫條件下使用的工業(yè)裝備越來(lái)越多,例如大型超低溫BOG壓縮機(jī)的工作溫度一般在-160℃甚至更低,因而對(duì)超低溫鑄造材料有著較大的需求。通常情況下,以鐵素體為基體的球墨鑄鐵材料能夠承受的溫度最低在-60℃左右,無(wú)法滿(mǎn)足更低溫度的應(yīng)用需求。高鎳奧氏體球墨鑄鐵隨著溫度的降低沒(méi)有韌-脆轉(zhuǎn)變現(xiàn)象,擁有著良好的低溫力學(xué)性能,因而在超低溫(-100℃以下)工業(yè)制造領(lǐng)域有著廣泛的應(yīng)用前景。目前,針對(duì)高鎳奧氏體球墨鑄鐵的相關(guān)研究主要集中在高溫性能方面,對(duì)于超低溫奧氏體球墨鑄鐵的研究極少,對(duì)其微觀(guān)組織、沖擊斷裂特征、示波沖擊斷裂過(guò)程以及沖擊裂紋的萌生和亞穩(wěn)擴(kuò)展規(guī)律并未見(jiàn)報(bào)道,因此本課題開(kāi)展了超低溫奧氏體球墨鑄鐵微觀(guān)組織與低溫沖擊斷裂行為的研究。對(duì)超低溫奧氏體球墨鑄鐵微觀(guān)組織及其對(duì)摩擦磨損行為的研究表明:超低溫奧氏體球墨鑄鐵的微觀(guān)組織主要由奧氏體、石墨球以及分布在晶界處的碳化物構(gòu)成,材料中的錳元素和鉻元素會(huì)偏析分布至材料基體中的奧氏體晶界處形成M23C6(M=Fe、Mn、Cr)型碳化物,其微觀(guān)硬度可達(dá)到1200HV以上,遠(yuǎn)高于奧氏體基體硬度值,因而使得材料的宏觀(guān)硬度得以提升。鉻元素有著比錳元素更強(qiáng)的碳化物形成能力,對(duì)材料的摩擦磨損性能影響更大。通過(guò)對(duì)不同鉻元素含量下的材料摩擦磨損后的形貌進(jìn)行分析發(fā)現(xiàn),該材料表現(xiàn)為磨粒磨損機(jī)制,其中鉻元素促進(jìn)形成的晶界碳化物作為硬質(zhì)顆粒使得材料的摩擦磨損性能顯著提高。采用低溫示波沖擊手段,針對(duì)不同合金(鎳、錳和鉻)元素下的超低溫奧氏體球墨鑄鐵低溫沖擊性能進(jìn)行研究,結(jié)果表明:隨著溫度的降低,不同合金元素下的超低溫奧氏體球墨鑄鐵沖擊性能均存在著相似的特征,即呈現(xiàn)先上升后下降的變化趨勢(shì),且鎳元素含量的變化對(duì)低溫沖擊性能存在著正相關(guān)的影響,而過(guò)多的錳元素和鉻元素加入會(huì)導(dǎo)致低溫沖擊性能惡化。采用掃描電子顯微鏡對(duì)沖擊斷口形貌進(jìn)行分析發(fā)現(xiàn):材料在室溫至-193℃的溫度區(qū)間內(nèi)均呈現(xiàn)了以石墨球或石墨球凹坑作為韌窩中心的韌性斷裂形貌特征,并且其沖擊斷口中石墨球數(shù)量與沖擊性能有著直接的因果關(guān)系,即石墨球越多則沖擊性能越好;碳化物數(shù)量的改變?cè)谑覝叵聦?duì)材料的沖擊性能影響并不明顯,而隨著溫度的降低其影響呈現(xiàn)增大的趨勢(shì),在-193℃的超低溫條件下會(huì)導(dǎo)致沖擊斷口中出現(xiàn)縱向微裂紋,嚴(yán)重破壞材料沖擊性能。在對(duì)超低溫奧氏體球墨鑄鐵低溫沖擊性能規(guī)律的研究基礎(chǔ)上,對(duì)不同溫度下的示波沖擊曲線(xiàn)進(jìn)行了深入分析,進(jìn)一步地揭示了材料的沖擊斷裂過(guò)程,結(jié)果表明:以斜率法與柔度變化率法相結(jié)合的方式對(duì)示波沖擊曲線(xiàn)進(jìn)行分段分析的方法,可以有效的定量表述材料的低溫沖擊斷裂過(guò)程;其中,沖擊裂紋的高載荷亞穩(wěn)擴(kuò)展能量的比重可以達(dá)到?jīng)_擊總能量的60%以上,且兩者的變化趨勢(shì)相一致,即隨溫度的降低呈現(xiàn)先上升后下降的趨勢(shì),因而高載荷亞穩(wěn)擴(kuò)展能量是決定低溫沖擊性能的主要因素;而該材料的低溫沖擊性能之所以呈現(xiàn)先上升后下降的趨勢(shì)(在-80℃時(shí)為極大值),是因?yàn)樵谑覝刂?80℃時(shí),高載荷亞穩(wěn)擴(kuò)展段的平均載荷對(duì)低溫沖擊性能起到了主導(dǎo)作用,而當(dāng)溫度繼續(xù)降低時(shí),高載荷亞穩(wěn)擴(kuò)展段的位移則成為了主導(dǎo)因素,研究還發(fā)現(xiàn),即便鎳元素含量變化這一規(guī)律仍然存在。同時(shí),采用三維激光共聚焦顯微鏡對(duì)沖擊斷口的幾何形貌進(jìn)行定量分析,對(duì)不同溫度下高載荷亞穩(wěn)擴(kuò)展段的表面粗糙度指數(shù)進(jìn)行統(tǒng)計(jì),驗(yàn)證了上述分析結(jié)論的正確性。由于超低溫奧氏體球墨鑄鐵實(shí)際示波沖擊曲線(xiàn)中高載荷亞穩(wěn)擴(kuò)展段的能量正好對(duì)應(yīng)著沖擊裂紋萌生與亞穩(wěn)擴(kuò)展過(guò)程中所吸收的能量,因此進(jìn)一步研究了沖擊裂紋萌生與亞穩(wěn)擴(kuò)展過(guò)程,結(jié)果表明:隨著溫度的降低,超低溫奧氏體球墨鑄鐵有著更好的抵抗沖擊裂紋萌生的能力;而前期抵抗沖擊裂紋亞穩(wěn)擴(kuò)展的能力受到溫度的影響,后期則受到溫度和材料中鎳元素含量變化的共同影響;材料基體中的石墨球(特別是相鄰的石墨球)和位于晶界處的碳化物是影響沖擊裂紋亞穩(wěn)擴(kuò)展路徑的最主要因素,而溫度的降低和材料中碳化物數(shù)量的增加都會(huì)加劇材料的脆性斷裂傾向;同時(shí),采用Schindler方法對(duì)不同鎳元素含量的超低溫奧氏體球墨鑄鐵在動(dòng)態(tài)載荷下的延性斷裂韌度JBl0.2進(jìn)行了計(jì)算后發(fā)現(xiàn),隨著溫度的降低,材料在動(dòng)態(tài)載荷下的延性斷裂韌度呈現(xiàn)持續(xù)升高的趨勢(shì),而當(dāng)溫度達(dá)到-80℃以下時(shí),這一趨勢(shì)會(huì)發(fā)生明顯的放緩。
[Abstract]:In recent years, more and more industrial equipments have been used under extremely low temperature conditions. For example, the working temperature of large-scale ultra-low temperature BOG compressor is generally - 160 C or even lower, so there is a great demand for ultra-low temperature casting materials. The high-nickel Austenitic Ductile iron has good mechanical properties at low temperature, so it has a broad application prospect in the field of ultra-low temperature (-100) industrial manufacturing. At present, the research on high-nickel Austenitic Ductile iron is mainly focused on. In the aspect of high temperature properties, there is little research on the microstructure, impact fracture characteristics, oscillographic impact fracture process and the law of initiation and metastable propagation of impact cracks of ultra-low temperature Austenitic Ductile iron. The microstructure and friction and wear behavior of ultra-low temperature Austenitic Ductile iron are studied. The results show that the microstructure of ultra-low temperature Austenitic Ductile iron is mainly composed of austenite, graphite nodules and carbides distributed at grain boundaries. Manganese and chromium elements in the material will segregate and distribute to austenite grain boundaries to form M. The micro-hardness of 23C6 (M=Fe, Mn, Cr) carbide can reach 1200HV, which is much higher than that of austenite matrix, so the macro-hardness of the material can be improved. The carbide forming ability of chromium element is stronger than that of manganese element, which has greater influence on the friction and wear properties of the material. The wear morphology analysis showed that the material exhibited abrasive wear mechanism, in which the grain boundary carbide promoted by chromium element was used as hard particles to improve the friction and wear properties of the material. The results show that the impact properties of ultra-low temperature Austenitic Ductile Iron with different alloying elements have similar characteristics as the temperature decreases, that is, the impact properties of ultra-low temperature Austenitic Ductile Iron increase first and then decrease, and the change of nickel content has a positive correlation with the impact properties at low temperature, while excessive manganese and chromium elements have a positive correlation. Scanning electron microscopy (SEM) was used to analyze the impact fracture morphology. It was found that the ductile fracture morphology with graphite sphere or graphite sphere pit as the dimple center was observed in the temperature range from room temperature to - 193 C. The number of graphite spheres and impact properties of the impact fracture surface were also observed. There is a direct causal relationship, that is, the more graphite spheres, the better the impact performance; the change of carbide number at room temperature has no obvious impact on the impact performance of the material, but with the decrease of temperature its impact shows an increasing trend, in the ultra-low temperature of - 193 C conditions will lead to the occurrence of longitudinal microcracks in the impact fracture, seriously destroying the impact of materials. On the basis of the study on the low temperature impact property of ultra-low temperature Austenitic Ductile iron, the oscillographic impact curves at different temperatures are analyzed in depth, and the impact fracture process of the material is further revealed. The results show that the oscillographic impact curves are segmented by slope method and flexibility change rate method. The analytical method can be used to quantitatively describe the low temperature impact fracture process of materials, in which the proportion of metastable propagation energy under high load can reach more than 60% of the total impact energy, and the change trend of the two is consistent, that is, the metastable propagation energy under high load increases first and then decreases with the decrease of temperature. The main factor determining the low temperature impact property is that the low temperature impact property of the material first increases and then decreases (the maximum value is at - 80 C), because the average load of the high load metastable extension plays a leading role in the low temperature impact property from room temperature to - 80 C, and the high load metastable property when the temperature continues to decrease. At the same time, the geometric morphology of impact fracture was quantitatively analyzed by using three-dimensional laser confocal microscopy, and the surface roughness index of metastable extended section with high load at different temperatures was calculated to verify the above results. The results show that the energy absorbed in the metastable growth stage of high load in the oscillographic shock curve of ultra-low temperature Austenitic Ductile Iron corresponds to the energy absorbed in the process of crack initiation and metastable growth. Therefore, the process of impact crack initiation and metastable growth is further studied. The results show that with the decrease of temperature, the energy absorbed in the metastable growth stage corresponds to the energy absorbed in the process of impact crack initiation and meta Low-temperature Austenitic Ductile iron has better resistance to impact crack initiation; the resistance to metastable propagation of impact crack in early stage is affected by temperature, while in later stage is affected by both temperature and nickel content in the material; graphite spheres in the matrix (especially adjacent graphite spheres) and carbonization at grain boundary Material is the most important factor affecting the metastable propagation path of impact crack, and the brittle fracture tendency is aggravated by the decrease of temperature and the increase of carbide content in the material. It is found that the ductile fracture toughness of the material increases continuously with the decrease of temperature under dynamic loading, and the trend slows down obviously when the temperature is below - 80%.
【學(xué)位授予單位】：沈陽(yáng)工業(yè)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：TG143.5

【相似文獻(xiàn)】

相關(guān)期刊論文 前10條

1 尹朝曦;;如何選用奧氏體鋼爐管[J];石油化工設(shè)備技術(shù);1991年02期

2 長(zhǎng)征;適合作人體植入物用的無(wú)鎳奧氏體鋼[J];金屬功能材料;2001年06期

3 長(zhǎng)征;適合作人體植入物用的無(wú)鎳奧氏體鋼[J];金屬功能材料;2002年01期

4 戴起勛,程曉農(nóng),趙玉濤,袁志鐘;工程應(yīng)用層次的奧氏體鋼計(jì)算設(shè)計(jì)系統(tǒng)[J];江蘇大學(xué)學(xué)報(bào)(自然科學(xué)版);2003年01期

5 王建泳;;奧氏體鋼應(yīng)變誘發(fā)馬氏體的試驗(yàn)研究[J];鍋爐技術(shù);2013年03期

6 薛侃時(shí);;高強(qiáng)度超低溫奧氏體鋼的發(fā)展[J];上海金屬(鋼鐵分冊(cè));1988年04期

7 G.G.Bondarenko;I.N.Borodulin;曹冬根;;改善奧氏體鋼耐熱性的化學(xué)處理方法[J];國(guó)外金屬熱處理;1988年02期

8 戴起勛,火樹(shù)鵬,陳原野;奧氏體鋼的形變誘發(fā)組織特征[J];江蘇工學(xué)院學(xué)報(bào);1993年04期

9 李曉剛;陳華;姚治銘;李勁;柯偉;;304奧氏體鋼的高溫高壓氫腐蝕[J];金屬學(xué)報(bào);1993年04期

10 В.Г.ΓОРБАЧ;謝揆燮;;制造儀表裝備和零件用馬氏體-奧氏體鋼[J];鑄鍛熱;1993年03期

相關(guān)會(huì)議論文 前5條

1 馬玉喜;榮凡;周榮;朗宇平;蔣業(yè)華;;高氮奧氏體鋼的韌脆轉(zhuǎn)變研究[A];2007中國(guó)鋼鐵年會(huì)論文集[C];2007年

2 范榮團(tuán);黃勝;郭桂英;;高錳奧氏體鋼中錳在晶界和晶內(nèi)的非平衡偏析[A];海峽兩岸電子顯微學(xué)研討會(huì)論文專(zhuān)集[C];1992年

3 劉國(guó)剛;;奧氏體爐管的壽命評(píng)價(jià)新技術(shù)及其應(yīng)用[A];全國(guó)火電大機(jī)組（300MW級(jí)）競(jìng)賽第34屆年會(huì)論文集[C];2005年

4 任大鵬;王小英;陳世勛;姜桂芬;;21-6-9奧氏體鋼與氘、氚氣體長(zhǎng)期作用后顯微組織[A];中國(guó)工程物理研究院科技年報(bào)（2000）[C];2000年

5 馬玉喜;;高氮奧氏體鋼的韌脆轉(zhuǎn)變與層錯(cuò)能之間的關(guān)系研究[A];2009年全國(guó)熱軋板帶生產(chǎn)技術(shù)交流會(huì)論文集[C];2009年

相關(guān)重要報(bào)紙文章 前1條

1 Motomichi KOYAMA Takahiro SAWAGUCHI 張濤 譯;日本研究奧氏體鋼的TWIP效應(yīng)[N];中國(guó)冶金報(bào);2013年

相關(guān)博士學(xué)位論文 前7條

1 張榮華;護(hù)環(huán)用改進(jìn)型超高氮奧氏體鋼的鑄態(tài)組織及熱變形行為[D];燕山大學(xué);2015年

2 王曼;新型奧氏體鋼顯微組織結(jié)構(gòu)穩(wěn)定性及力學(xué)性能的研究[D];北京科技大學(xué);2017年

3 姜珂;超低溫奧氏體球墨鑄鐵微觀(guān)組織與低溫沖擊斷裂行為的研究[D];沈陽(yáng)工業(yè)大學(xué);2017年

4 付瑞東;高錳奧氏體鋼低溫沿晶脆性的產(chǎn)生原因及抑制方法的研究[D];燕山大學(xué);2003年

5 姜雯;超級(jí)馬氏體不銹鋼組織性能及逆變奧氏體機(jī)制的研究[D];昆明理工大學(xué);2014年

6 婁建新;珠光體鋼與奧氏體鋼異質(zhì)接頭碳遷移機(jī)制及影響因素研究[D];沈陽(yáng)工業(yè)大學(xué);2014年

7 蔣志俊;過(guò)冷高氮奧氏體中溫回火分解機(jī)制的研究[D];上海交通大學(xué);2010年

相關(guān)碩士學(xué)位論文 前10條

1 王崗;高比強(qiáng)鐵錳基奧氏體鋼設(shè)計(jì)基礎(chǔ)研究[D];大連交通大學(xué);2015年

2 方曉陽(yáng);加工工藝對(duì)奧氏體先進(jìn)高強(qiáng)鋼組織與力學(xué)性能的影響[D];浙江大學(xué);2016年

3 徐天帥;軋制及熱處理工藝對(duì)Fe-7Mn鋼的顯微結(jié)構(gòu)與拉伸性能的影響[D];東北大學(xué);2014年

4 任善平;三種奧氏體鋼在模擬氣氛/煤灰環(huán)境中的腐蝕行為研究[D];南昌航空大學(xué);2016年

5 胡昌文;珠光體鋼和奧氏體鋼焊接工藝優(yōu)化及其接頭性能研究[D];河南科技大學(xué);2016年

6 匡步肖;奧氏體含量及其機(jī)械穩(wěn)定性對(duì)Fe-15Cr-1Mo-0.4N-0.3C不銹鋼拉伸性能的影響[D];武漢科技大學(xué);2016年

7 康杰;碳氮增強(qiáng)合金化奧氏體鋼及其力學(xué)行為的研究[D];燕山大學(xué);2012年

8 李曉英;奧氏體變形對(duì)低碳高硅鋼等溫貝氏體組織的影響[D];燕山大學(xué);2013年

9 賀延明;奧氏體鋼冷軋及退火后的組織與性能研究[D];燕山大學(xué);2014年

10 常帥;高錳奧氏體鋼中碳化釩沉淀機(jī)制與強(qiáng)化機(jī)理的研究[D];大連交通大學(xué);2013年

，

本文編號(hào)：2181280