發(fā)布時(shí)間：2018-04-02 21:19

  本文選題：不銹鋼凸焊　切入點(diǎn)：微觀組織　出處：《吉林大學(xué)》2017年碩士論文

【摘要】：隨著工業(yè)的發(fā)展和工藝的優(yōu)化,奧氏體不銹鋼因其外觀光澤度好,耐高溫、耐腐蝕性能優(yōu)良以及加工性能好等特點(diǎn)被廣泛應(yīng)用于各工業(yè)制造領(lǐng)域。不銹鋼凸焊工藝作為一種比較特殊的電阻點(diǎn)焊工藝方法,具有焊接熱量集中、工件變形小等優(yōu)點(diǎn),在管材、線材以及一些特殊結(jié)構(gòu)的焊接上被應(yīng)用。本文就醫(yī)療器械行業(yè)的一種較特殊的不銹鋼凸焊結(jié)構(gòu)焊接接頭組織及其質(zhì)量的無(wú)損檢測(cè)方法進(jìn)行研究,以解決相關(guān)焊接產(chǎn)品的質(zhì)量控制問(wèn)題。不銹鋼凸焊接頭的特殊結(jié)構(gòu)導(dǎo)致凸焊接頭質(zhì)量的檢測(cè)具有一定困難。目前,國(guó)內(nèi)外工業(yè)生產(chǎn)中的不銹鋼凸焊質(zhì)量評(píng)價(jià)方法主要有兩種,即焊接后的破壞性檢測(cè)和焊接過(guò)程中的在線監(jiān)測(cè),但這兩種方法均存在一定不足。超聲波檢測(cè)是一種靈敏度高、檢測(cè)范圍廣、原理簡(jiǎn)單、操作方便、易實(shí)現(xiàn)現(xiàn)場(chǎng)檢測(cè)的無(wú)損檢測(cè)技術(shù)。因此,不銹鋼凸焊的超聲波檢測(cè)研究對(duì)工業(yè)生產(chǎn)有重要的價(jià)值。本文對(duì)316L不銹鋼封閉式中空隔條進(jìn)行雙面凸焊,一面直接焊接,另一面利用銅柱對(duì)電流與壓力的傳導(dǎo)作用進(jìn)行焊接。通過(guò)對(duì)不銹鋼電阻凸焊接頭進(jìn)行金相組織觀察分析及力學(xué)性能檢測(cè),結(jié)合超聲波掃描檢測(cè)信號(hào)分析,研究不銹鋼電阻凸焊接頭連接特點(diǎn)及接頭質(zhì)量。不銹鋼凸焊接頭是一種塑性連接區(qū)域相對(duì)較大的特殊結(jié)構(gòu),其超聲波檢測(cè)分析主要有兩個(gè)難點(diǎn):一是通過(guò)超聲波信號(hào)分析反映接頭內(nèi)部結(jié)構(gòu),尤其是塑性連接區(qū)域與熔核區(qū)域的區(qū)分;二是將超聲波分析結(jié)果與實(shí)際微觀組織及機(jī)械性能結(jié)合進(jìn)行凸焊接頭質(zhì)量評(píng)估。本文從解決上述問(wèn)題出發(fā),對(duì)316L不銹鋼凸焊接頭進(jìn)行金相觀察、拉伸試驗(yàn)、顯微硬度測(cè)試,并結(jié)合掃描電鏡分析、能譜分析,研究凸焊接頭結(jié)構(gòu)連接狀態(tài)及力學(xué)性能。研究發(fā)現(xiàn),316L不銹鋼凸焊接頭金相組織中,熔核和母材分界清晰,有一定的熱影響區(qū),其熱影響區(qū)存在晶粒長(zhǎng)大現(xiàn)象,熔核區(qū)組織為不同狀態(tài)的鐵素體分布在奧氏體基體上,結(jié)晶方式為鐵素體-奧氏體方式。拉伸試驗(yàn)與顯微硬度測(cè)試表明兩種316L不銹鋼凸焊接頭強(qiáng)度均超過(guò)母材強(qiáng)度。通過(guò)分析掃描電鏡下斷口形貌判斷其斷裂機(jī)制為微孔聚集型韌性斷裂。通過(guò)能譜分析發(fā)現(xiàn)316L不銹鋼凸焊接頭具有良好的耐腐蝕性,其原因是Cr、Ni、Mn等合金元素的存在。對(duì)于未剝離的凸焊接頭其斷口顯示無(wú)元素偏聚現(xiàn)象,也無(wú)有害相析出,結(jié)合力學(xué)性能測(cè)試,推斷其仍滿足凸焊工藝質(zhì)量要求。本文以凸焊試樣超聲檢測(cè)數(shù)據(jù)為基礎(chǔ),分析凸焊接頭各個(gè)區(qū)域的A回波信號(hào),研究超聲A回波信號(hào)的時(shí)域特征及變化規(guī)律。時(shí)域分析結(jié)果能有效表達(dá)出凸焊各區(qū)域特征,但未能有效區(qū)分塑性連接區(qū)和熔核區(qū)。本文利用加窗濾波處理的FFT變換,研究發(fā)現(xiàn)經(jīng)過(guò)變換的超聲波回波幅值特征曲線能有效反映凸焊連接結(jié)構(gòu)特點(diǎn)。試驗(yàn)結(jié)果與金相分析結(jié)果吻合良好,實(shí)現(xiàn)了不銹鋼凸焊接頭塑性連接區(qū)域與熔核的識(shí)別,滿足不銹鋼凸焊接頭的檢測(cè)需要。本文以金相組織分析、力學(xué)性能分析為基礎(chǔ),結(jié)合超聲波C成像分析,通過(guò)連接狀態(tài)閥值標(biāo)定、等效能量計(jì)算,研究接頭性能與超聲波信號(hào)之間的聯(lián)系,研究發(fā)現(xiàn)等效能量計(jì)算結(jié)果與實(shí)際力學(xué)性能呈負(fù)相關(guān)關(guān)系。同時(shí)本文比較了凸焊兩面接頭的質(zhì)量差異,通過(guò)對(duì)比研究發(fā)現(xiàn)無(wú)銅柱凸焊接頭質(zhì)量要稍優(yōu)于有銅柱凸焊接頭的質(zhì)量。
[Abstract]:With the development and optimization of process industry, austenitic stainless steel because of the appearance of gloss, high temperature resistance, corrosion resistance and excellent and good processing performance and is widely used in various industrial manufacturing field. The convex welding process of stainless steel as a kind of special resistance spot welding technology, welding with heat concentrated, small deformation of the workpiece etc. the advantages, in pipe, welding wire and some special structure has been used in this study. In this paper, a nondestructive testing method of special stainless steel welding structure of the medical device industry and the microstructure of the welding joint quality, quality control to solve the problem of welding products. The special structure of stainless steel welding joint quality lead to the detection of convex welding joint is very difficult. At present, there are mainly two kinds of stainless steel welding quality evaluation of domestic and foreign industrial production methods, namely after welding destructive inspection Measurement and monitoring of the welding process, but these two methods have some shortcomings. The ultrasonic detection is a kind of high sensitivity, wide detection range, simple principle, convenient operation, easy realization of nondestructive testing technology of field detection. Therefore, ultrasonic testing of stainless steel welding research has important value in industrial production. In this paper, 316L stainless steel closed hollow spacing strip for double-sided welding, welding on the other side by side directly, conduction current and pressure on copper welding. Detect the observation of microstructure analysis and mechanical properties of stainless steel by resistance projection welding head, combined with the analysis of ultrasonic detection signal of stainless steel resistance projection welding head connection characteristics and the joint quality of stainless steel. Welding connection is a plastic connecting area relatively special structure, the ultrasonic detection and analysis there are two main difficulties: one is through Ultrasonic signal analysis reflect the internal structure of joints, especially between plastic connection area and nugget area; two is the ultrasonic analysis results and the actual microstructure and mechanical properties of welding joint quality assessment. This paper from convex to solve the above problems, through metallographic observation, 316L stainless steel welding joint tensile test, microhardness test and scanning electron microscope analysis, energy spectrum analysis, and mechanical properties of welded joint of connecting convex structure. The study found that the microstructure of 316L stainless steel welding joint, nugget and base metal have clear boundaries, the heat affected zone of the grains in the heat affected zone growth phenomenon, organization the nugget zone for different states of ferrite distributed in the austenitic matrix, the crystallization mode for ferrite austenite. The tensile test and microhardness test showed that two kinds of 316L stainless steel welding joint strength are convex More than the strength of the base material. Through the analysis of SEM fractography determine its fracture mechanism is ductile fracture. The porous aggregate through spectrum analysis found that 316L stainless steel welded convex head has good corrosion resistance, the reason is that Cr, Ni, Mn and other alloy elements. For welding joint of the fracture shows without stripping no element segregation, no harmful phases, combining the mechanical performance test, the inference can still meet the requirements. The quality of projection welding process based on welding ultrasonic testing sample data, analysis of A echo signal bump joint of each area, time domain characteristics and variation of ultrasonic echo signals of A time domain analysis results. Can effectively express the regional characteristics of welding, but failed to effectively distinguish between the plastic zone and the nugget zone. The connection with the FFT transform window filter in this paper, the study found that after the ultrasonic echo amplitude transform characteristic curve The line can effectively reflect the welding connection structure features. The experimental results are in good agreement with the results of metallographic analysis, the identification of the connection area and the plastic head of nuclear fusion welding of stainless steel stainless steel welding convex, meet the detection needs. Based on the joint microstructure analysis, mechanical performance analysis as the foundation, combined with the analysis of ultrasonic C imaging, through the connection state threshold calibration, the equivalent energy calculation between joint performance and ultrasonic signal, study found that the equivalent energy calculation results with the actual mechanical performance was negatively correlated. At the same time, this paper compares the differences in the quality of welding joint surface two, through the comparative study found that welding quality was better than that of a convex welding joint quality without pillars convex pillars.

【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TG441.7

【相似文獻(xiàn)】

相關(guān)期刊論文 前2條

1 才坤;李光輝;張執(zhí);;凸焊接頭性能的影響因素[J];河南科技;2011年04期

2 周世權(quán),丁振兵,陳士民;厚大螺母與鍍鋅薄鋼板環(huán)凸焊接頭組織與性能[J];電焊機(jī);1999年05期

相關(guān)碩士學(xué)位論文 前1條

1 蒲丹;不銹鋼凸焊接頭組織與超聲波檢測(cè)研究[D];吉林大學(xué);2017年

，

本文編號(hào)：1702143