一、氮氣孔的形成(cheng)機理

  在21.5Cr5Mn1.5Ni0.25N含(han)氮(dan)(dan)(dan)雙相(xiang)(xiang)(xiang)鋼凝(ning)(ning)(ning)(ning)固(gu)過程(cheng)中(zhong)(zhong)(zhong)，氮(dan)(dan)(dan)氣(qi)孔形(xing)(xing)成(cheng)和(he)(he)凝(ning)(ning)(ning)(ning)固(gu)前(qian)沿處(chu)［％N]1iq隨距離(li)變化的(de)(de)(de)(de)(de)(de)規律(lv)如(ru)圖(tu)2-55所示。由于糊狀區(qu)(qu)內大(da)量枝(zhi)(zhi)晶網狀結構的(de)(de)(de)(de)(de)(de)形(xing)(xing)成(cheng)，液(ye)(ye)(ye)相(xiang)(xiang)(xiang)的(de)(de)(de)(de)(de)(de)對(dui)(dui)流只存在于一次枝(zhi)(zhi)晶尖端(duan)位置附近。且(qie)枝(zhi)(zhi)晶間幾乎無液(ye)(ye)(ye)相(xiang)(xiang)(xiang)的(de)(de)(de)(de)(de)(de)流動(dong)。因此，枝(zhi)(zhi)晶間殘(can)(can)余液(ye)(ye)(ye)相(xiang)(xiang)(xiang)中(zhong)(zhong)(zhong)的(de)(de)(de)(de)(de)(de)氮(dan)(dan)(dan)傳質(zhi)主要(yao)依(yi)靠氮(dan)(dan)(dan)的(de)(de)(de)(de)(de)(de)擴散行(xing)為，且(qie)糊狀區(qu)(qu)內氮(dan)(dan)(dan)傳質(zhi)速(su)率非常小(xiao)。初始(shi)(shi)相(xiang)(xiang)(xiang)貧氮(dan)(dan)(dan)鐵素(su)體相(xiang)(xiang)(xiang)8的(de)(de)(de)(de)(de)(de)氮(dan)(dan)(dan)溶解度(du)(du)和(he)(he)糊狀區(qu)(qu)的(de)(de)(de)(de)(de)(de)氮(dan)(dan)(dan)傳質(zhi)速(su)率較低，導致在貧氮(dan)(dan)(dan)鐵素(su)體相(xiang)(xiang)(xiang)枝(zhi)(zhi)晶附近的(de)(de)(de)(de)(de)(de)液(ye)(ye)(ye)相(xiang)(xiang)(xiang)中(zhong)(zhong)(zhong)出(chu)現氮(dan)(dan)(dan)富(fu)集(ji)(ji)，且(qie)［％N]iq迅速(su)增大(da)，如(ru)圖(tu)2-55(a)所示。根據(ju)Yang和(he)(he) Leel70]、Svyazhin 等、Ridolfi 和(he)(he) Tassal的(de)(de)(de)(de)(de)(de)報道可(ke)知(zhi)(zhi)，當［％N]iq的(de)(de)(de)(de)(de)(de)最大(da)值超過氮(dan)(dan)(dan)氣(qi)泡(pao)(pao)形(xing)(xing)成(cheng)的(de)(de)(de)(de)(de)(de)臨界氮(dan)(dan)(dan)質(zhi)量分數（［％N]pore)時(shi)，該區(qu)(qu)域(yu)有氣(qi)泡(pao)(pao)形(xing)(xing)成(cheng)的(de)(de)(de)(de)(de)(de)可(ke)能(neng)性(xing)，如(ru)圖(tu)2-55(b)所示。在后(hou)續的(de)(de)(de)(de)(de)(de)凝(ning)(ning)(ning)(ning)固(gu)過程(cheng)中(zhong)(zhong)(zhong)，隨著(zhu)包(bao)晶反(fan)應的(de)(de)(de)(de)(de)(de)進(jin)行(xing)，富(fu)氮(dan)(dan)(dan)奧氏(shi)體相(xiang)(xiang)(xiang)γ以(yi)(yi)異質(zhi)形(xing)(xing)核的(de)(de)(de)(de)(de)(de)方式在鐵素(su)體相(xiang)(xiang)(xiang)8枝(zhi)(zhi)晶的(de)(de)(de)(de)(de)(de)表面(mian)(mian)開始(shi)(shi)形(xing)(xing)核長(chang)大(da)，逐漸包(bao)裹鐵素(su)體相(xiang)(xiang)(xiang)枝(zhi)(zhi)晶表面(mian)(mian)，并開始(shi)(shi)捕獲殘(can)(can)余液(ye)(ye)(ye)相(xiang)(xiang)(xiang)中(zhong)(zhong)(zhong)的(de)(de)(de)(de)(de)(de)氮(dan)(dan)(dan)氣(qi)泡(pao)(pao)，對(dui)(dui)比(bi)圖(tu)2-51和(he)(he)圖(tu)2-56可(ke)知(zhi)(zhi)，此時(shi)枝(zhi)(zhi)晶間殘(can)(can)余［％N]1ig的(de)(de)(de)(de)(de)(de)增長(chang)速(su)率減(jian)小(xiao)。對(dui)(dui)平衡(heng)凝(ning)(ning)(ning)(ning)固(gu)而言(yan)，殘(can)(can)余液(ye)(ye)(ye)相(xiang)(xiang)(xiang)中(zhong)(zhong)(zhong)氮(dan)(dan)(dan)氣(qi)泡(pao)(pao)形(xing)(xing)成(cheng)以(yi)(yi)后(hou)，氮(dan)(dan)(dan)的(de)(de)(de)(de)(de)(de)富(fu)集(ji)(ji)程(cheng)度(du)(du)減(jian)弱，［％N]1iq增長(chang)速(su)率的(de)(de)(de)(de)(de)(de)減(jian)小(xiao)程(cheng)度(du)(du)明顯(xian)；相(xiang)(xiang)(xiang)比(bi)之下，Scheil凝(ning)(ning)(ning)(ning)固(gu)過程(cheng)中(zhong)(zhong)(zhong)，氮(dan)(dan)(dan)氣(qi)泡(pao)(pao)形(xing)(xing)成(cheng)以(yi)(yi)后(hou)，殘(can)(can)余液(ye)(ye)(ye)相(xiang)(xiang)(xiang)中(zhong)(zhong)(zhong)氮(dan)(dan)(dan)富(fu)集(ji)(ji)狀態有所緩解，但幅度(du)(du)很小(xiao)。隨著(zhu)凝(ning)(ning)(ning)(ning)固(gu)界面(mian)(mian)的(de)(de)(de)(de)(de)(de)進(jin)一步推移，被(bei)捕獲的(de)(de)(de)(de)(de)(de)氮(dan)(dan)(dan)氣(qi)泡(pao)(pao)在奧氏(shi)體相(xiang)(xiang)(xiang)表面(mian)(mian)開始(shi)(shi)長(chang)大(da)，并沿凝(ning)(ning)(ning)(ning)固(gu)方向拉(la)長(chang)，如(ru)圖(tu)2-55(c)所示。

  氮(dan)氣(qi)孔(kong)(kong)(kong)沿徑向生(sheng)長，生(sheng)長方(fang)向與(yu)凝(ning)固方(fang)向一致，那么氮(dan)氣(qi)孔(kong)(kong)(kong)初始形成位置靠近鑄(zhu)錠邊部，且氮(dan)氣(qi)泡初始位置邊緣全由奧氏(shi)(shi)體(ti)相γ構成（圖2-57中I區），與(yu)圖2-55描述相符。隨著(zhu)氮(dan)氣(qi)孔(kong)(kong)(kong)被(bei)拉長，鐵素(su)體(ti)相和奧氏(shi)(shi)體(ti)相以體(ti)積分數比約(yue)為0.92的關系(xi)交替在(zai)氮(dan)氣(qi)泡周圍形成，直到氮(dan)氣(qi)孔(kong)(kong)(kong)閉合。凝(ning)固結束后，氮(dan)氣(qi)孔(kong)(kong)(kong)的宏(hong)觀形貌類似于橢圓形，與(yu)Wei等的研(yan)究結果一致

二、氮(dan)微觀偏析對氮(dan)氣(qi)孔的影響

  氮(dan)(dan)的(de)(de)(de)(de)(de)分(fen)(fen)配系(xi)數(shu)較(jiao)小，導致(zhi)液(ye)相(xiang)(xiang)向(xiang)固(gu)(gu)相(xiang)(xiang)轉變的(de)(de)(de)(de)(de)過(guo)程(cheng)中(zhong)(zhong)(zhong)，固(gu)(gu)相(xiang)(xiang)會將(jiang)多(duo)(duo)余的(de)(de)(de)(de)(de)氮(dan)(dan)轉移到殘(can)余液(ye)相(xiang)(xiang)中(zhong)(zhong)(zhong)，形(xing)(xing)成氮(dan)(dan)偏析(xi)。在(zai)氮(dan)(dan)偏析(xi)程(cheng)度逐(zhu)漸加重的(de)(de)(de)(de)(de)過(guo)程(cheng)中(zhong)(zhong)(zhong)，當殘(can)余液(ye)相(xiang)(xiang)中(zhong)(zhong)(zhong)氮(dan)(dan)質量分(fen)(fen)數(shu)超過(guo)其飽(bao)和(he)度時，極易形(xing)(xing)成氮(dan)(dan)氣(qi)(qi)(qi)泡(pao)。隨著(zhu)凝(ning)固(gu)(gu)的(de)(de)(de)(de)(de)進行(xing)，若氣(qi)(qi)(qi)泡(pao)無法上浮(fu)而(er)被(bei)捕獲，凝(ning)固(gu)(gu)結束后(hou)就會在(zai)鑄(zhu)錠(ding)內(nei)部(bu)形(xing)(xing)成氣(qi)(qi)(qi)孔(kong)。因此，凝(ning)固(gu)(gu)過(guo)程(cheng)中(zhong)(zhong)(zhong)氮(dan)(dan)偏析(xi)和(he)溶(rong)解度對鑄(zhu)錠(ding)中(zhong)(zhong)(zhong)最終氮(dan)(dan)氣(qi)(qi)(qi)孔(kong)的(de)(de)(de)(de)(de)形(xing)(xing)成有(you)至關重要(yao)的(de)(de)(de)(de)(de)作用。氮(dan)(dan)氣(qi)(qi)(qi)孔(kong)多(duo)(duo)數(shu)情(qing)況下與疏(shu)松(song)(song)縮孔(kong)共存，內(nei)壁凹(ao)凸不(bu)平呈現(xian)裂紋(wen)狀，且整個氣(qi)(qi)(qi)孔(kong)形(xing)(xing)狀不(bu)規則，如圖2-58所(suo)示(shi)。此類氣(qi)(qi)(qi)孔(kong)不(bu)僅與鋼液(ye)中(zhong)(zhong)(zhong)氣(qi)(qi)(qi)泡(pao)的(de)(de)(de)(de)(de)形(xing)(xing)成有(you)關，還受凝(ning)固(gu)(gu)收(shou)縮等(deng)因素的(de)(de)(de)(de)(de)影響，且多(duo)(duo)數(shu)分(fen)(fen)布于鑄(zhu)錠(ding)心(xin)(xin)部(bu)，尤其在(zai)中(zhong)(zhong)(zhong)心(xin)(xin)等(deng)軸(zhou)晶(jing)(jing)區(qu)(qu)。這主要(yao)由于中(zhong)(zhong)(zhong)心(xin)(xin)等(deng)軸(zhou)晶(jing)(jing)區(qu)(qu)內(nei)枝晶(jing)(jing)生長較(jiao)發達，容(rong)易形(xing)(xing)成復雜的(de)(de)(de)(de)(de)網狀結構，從而(er)將(jiang)液(ye)相(xiang)(xiang)分(fen)(fen)割成無數(shu)個獨立的(de)(de)(de)(de)(de)液(ye)相(xiang)(xiang)區(qu)(qu)域，當發生凝(ning)固(gu)(gu)收(shou)縮時，難以進行(xing)補縮，在(zai)形(xing)(xing)成疏(shu)松(song)(song)縮孔(kong)的(de)(de)(de)(de)(de)同時，局部(bu)鋼液(ye)靜壓力降低，促使氮(dan)(dan)從殘(can)余液(ye)相(xiang)(xiang)中(zhong)(zhong)(zhong)析(xi)出，從而(er)形(xing)(xing)成了氮(dan)(dan)氣(qi)(qi)(qi)孔(kong)和(he)疏(shu)松(song)(song)縮孔(kong)共存的(de)(de)(de)(de)(de)宏觀缺陷。

  平(ping)衡凝固(gu)時，19Cr14Mn0.9N含(han)氮(dan)奧(ao)氏(shi)體不(bu)(bu)銹(xiu)鋼殘余液相中氮(dan)偏(pian)析(xi)與(yu)體系氮(dan)溶解(jie)度(du)的(de)差(cha)(cha)值如(ru)圖2-59所示。凝固(gu)初期鐵素體阱（ferrite trap)的(de)形(xing)(xing)成(cheng)，導致氮(dan)溶解(jie)度(du)的(de)降低，進(jin)而使氮(dan)偏(pian)析(xi)與(yu)體系氮(dan)溶解(jie)度(du)差(cha)(cha)值呈現出略微增大的(de)趨勢。但(dan)在(zai)后續凝固(gu)過(guo)(guo)程中，隨(sui)著鐵素體阱的(de)消失以及富氮(dan)奧(ao)氏(shi)體相的(de)不(bu)(bu)斷形(xing)(xing)成(cheng)，差(cha)(cha)值減小(xiao)；在(zai)整個凝固(gu)過(guo)(guo)程中差(cha)(cha)值始終較(jiao)(jiao)小(xiao)，且變化幅度(du)較(jiao)(jiao)窄。對(dui)于19Cr14Mn0.9N 含(han)氮(dan)奧(ao)氏(shi)體不(bu)(bu)銹(xiu)鋼，液相中氮(dan)氣泡(pao)的(de)形(xing)(xing)成(cheng)趨勢較(jiao)(jiao)小(xiao)，難以在(zai)鑄錠內(nei)形(xing)(xing)成(cheng)獨(du)立(li)內(nei)壁光滑的(de)規則(ze)氮(dan)氣孔。

  此(ci)外，目(mu)前有人對奧(ao)(ao)氏(shi)體(ti)鋼(gang)凝(ning)(ning)固過程中(zhong)(zhong)氮(dan)氣(qi)(qi)孔(kong)(kong)的(de)(de)(de)形(xing)(xing)成(cheng)(cheng)(cheng)(cheng)進(jin)行了(le)大(da)(da)量研究(jiu)(jiu)，如Yang和Leel901研究(jiu)(jiu)了(le)奧(ao)(ao)氏(shi)體(ti)鋼(gang)16Cr3NixMn(x=9和11)凝(ning)(ning)固過程中(zhong)(zhong)壓力和初始(shi)氮(dan)質量分數等因素對氮(dan)氣(qi)(qi)孔(kong)(kong)形(xing)(xing)成(cheng)(cheng)(cheng)(cheng)的(de)(de)(de)影響(xiang)規律，并(bing)建(jian)立了(le)相(xiang)應(ying)的(de)(de)(de)預測模型。Ridolfi和Tassal[84]分析了(le)氮(dan)偏(pian)(pian)析、合金(jin)元素、冷卻(que)速(su)率(lv)(lv)以(yi)(yi)及枝晶間距(ju)對奧(ao)(ao)氏(shi)體(ti)鋼(gang)中(zhong)(zhong)氮(dan)氣(qi)(qi)孔(kong)(kong)的(de)(de)(de)影響(xiang)規律，并(bing)揭示(shi)了(le)奧(ao)(ao)氏(shi)體(ti)鋼(gang)中(zhong)(zhong)氮(dan)氣(qi)(qi)孔(kong)(kong)形(xing)(xing)成(cheng)(cheng)(cheng)(cheng)機(ji)理(li)。然而，目(mu)前對于(yu)雙相(xiang)鋼(gang)中(zhong)(zhong)氮(dan)氣(qi)(qi)孔(kong)(kong)形(xing)(xing)成(cheng)(cheng)(cheng)(cheng)的(de)(de)(de)研究(jiu)(jiu)較(jiao)少，且(qie)主要集中(zhong)(zhong)在合金(jin)元素、鑄造方式、冷卻(que)速(su)率(lv)(lv)等因素對氮(dan)氣(qi)(qi)孔(kong)(kong)影響(xiang)規律的(de)(de)(de)研究(jiu)(jiu)，鮮有對雙相(xiang)鋼(gang)中(zhong)(zhong)氮(dan)氣(qi)(qi)孔(kong)(kong)形(xing)(xing)成(cheng)(cheng)(cheng)(cheng)機(ji)理(li)的(de)(de)(de)報道(dao)。以(yi)(yi)21.5Cr5Mn1.5Ni0.25N含(han)氮(dan)雙相(xiang)鋼(gang)為例，氮(dan)偏(pian)(pian)析與溶(rong)解(jie)度的(de)(de)(de)差(cha)值(zhi)在整個凝(ning)(ning)固過程中(zhong)(zhong)的(de)(de)(de)變化趨勢，如圖(tu)2-59所示(shi)。隨著(zhu)凝(ning)(ning)固的(de)(de)(de)進(jin)行，氮(dan)偏(pian)(pian)析始(shi)終(zhong)大(da)(da)于(yu)氮(dan)溶(rong)解(jie)度，且(qie)差(cha)值(zhi)呈(cheng)現出快速(su)增大(da)(da)的(de)(de)(de)趨勢。因此(ci)，在21.5Cr5Mn1.5Ni0.25N 含(han)氮(dan)雙相(xiang)鋼(gang)凝(ning)(ning)固過程中(zhong)(zhong)，氮(dan)偏(pian)(pian)析嚴(yan)重，殘余(yu)液相(xiang)內(nei)氮(dan)氣(qi)(qi)泡(pao)形(xing)(xing)成(cheng)(cheng)(cheng)(cheng)趨勢較(jiao)大(da)(da)，明顯(xian)高于(yu)19Cr14Mn0.9N含(han)氮(dan)奧(ao)(ao)氏(shi)體(ti)不銹鋼(gang)。

  氮(dan)氣泡(pao)形成和(he)長大具(ju)有重(zhong)要(yao)的(de)作(zuo)用(yong)（圖2-60).其中，σ為(wei)氣液界面(mian)的(de)表(biao)面(mian)張(zhang)力(li)，r為(wei)氣泡(pao)半徑。結合(he)經典形核理(li)論，氮(dan)氣泡(pao)在(zai)鋼液中穩定存在(zai)的(de)必要(yao)條件為(wei)氣泡(pao)內壓力(li)大于(yu)作(zuo)用(yong)于(yu)氣泡(pao)的(de)所有壓力(li)之和(he)，即

  式中，Aso由凝固過程(cheng)中除氮以(yi)外其他合金元(yuan)素的微觀偏析(xi)(xi)(xi)進行計算，其值(zhi)隨著(zhu)枝(zhi)(zhi)晶(jing)(jing)間(jian)(jian)殘余(yu)液相中氮溶解(jie)度的增(zeng)(zeng)加而(er)減小，表征了(le)枝(zhi)(zhi)晶(jing)(jing)間(jian)(jian)殘余(yu)液相中氮溶解(jie)度對氮氣(qi)泡(pao)形成的影(ying)響程(cheng)度；Ase表征了(le)枝(zhi)(zhi)晶(jing)(jing)間(jian)(jian)氮偏析(xi)(xi)(xi)對氮氣(qi)泡(pao)形成的影(ying)響程(cheng)度，可由凝固過程(cheng)中枝(zhi)(zhi)晶(jing)(jing)間(jian)(jian)殘余(yu)液相中氮偏析(xi)(xi)(xi)計算獲得(de)，其值(zhi)隨著(zhu)氮偏析(xi)(xi)(xi)的增(zeng)(zeng)大(da)(da)而(er)增(zeng)(zeng)大(da)(da)。此(ci)外，用于計算Aso和Ase時所(suo)需的合金元(yuan)素偏析(xi)(xi)(xi)均由鋼凝固相變(bian)所(suo)致(zhi)。

  氮(dan)氣(qi)(qi)泡的形核和長大(da)過(guo)(guo)程(cheng)(cheng)復雜，且(qie)影(ying)響(xiang)因素眾多，包(bao)括凝(ning)(ning)(ning)固(gu)(gu)收(shou)縮、冶煉環境以及坩堝材質等。因此，很(hen)難采(cai)用(yong)Pg值精確預測(ce)凝(ning)(ning)(ning)固(gu)(gu)過(guo)(guo)程(cheng)(cheng)中(zhong)(zhong)氮(dan)氣(qi)(qi)泡的形成和長大(da)。然(ran)而基于Yang等的實驗研究(jiu)［70,77],在(zai)評估凝(ning)(ning)(ning)固(gu)(gu)壓力(li)、合金成分(fen)等因素對氮(dan)氣(qi)(qi)泡形成的影(ying)響(xiang)程(cheng)(cheng)度(du)時，Pg起關(guan)鍵(jian)作(zuo)用(yong)。實際凝(ning)(ning)(ning)固(gu)(gu)過(guo)(guo)程(cheng)(cheng)介于平衡凝(ning)(ning)(ning)固(gu)(gu)（固(gu)(gu)／液相中(zhong)(zhong)溶(rong)質完(wan)全擴(kuo)散）和Scheil凝(ning)(ning)(ning)固(gu)(gu)（固(gu)(gu)相無溶(rong)質擴(kuo)散，液相中(zhong)(zhong)完(wan)全擴(kuo)散）之間70].因此，可分(fen)別計算(suan)平衡凝(ning)(ning)(ning)固(gu)(gu)和Scheil凝(ning)(ning)(ning)固(gu)(gu)過(guo)(guo)程(cheng)(cheng)中(zhong)(zhong)的Aso、Ase和Pg,闡明實際凝(ning)(ning)(ning)固(gu)(gu)過(guo)(guo)程(cheng)(cheng)中(zhong)(zhong)壓力(li)等因素對氮(dan)氣(qi)(qi)泡形成的影(ying)響(xiang)規律(lv)。

  現以21.5Cr5Mn1.5Ni0.25N含(han)氮雙相鋼D1鑄錠為(wei)例，對凝固(gu)過程中Aso、Ase和P8的變(bian)化趨勢進行(xing)計算。圖2-61描述了(le)ΔAso(=Asa-Aso,0)和AAse(=Ase-Ase,o)隨固(gu)相質量分數的變(bian)化趨勢（Aso,0和Asc,0分別為(wei)D1鑄錠凝固(gu)時Aso和Ase的初始值）。

  在(zai)平衡凝(ning)(ning)(ning)固(gu)(gu)和(he)Scheil凝(ning)(ning)(ning)固(gu)(gu)過(guo)(guo)程中，ΔAso的(de)(de)最(zui)(zui)小值(zhi)分(fen)(fen)別(bie)為(wei)－0.145和(he)－0.397,與(yu)(yu)此(ci)相(xiang)對(dui)(dui)(dui)應的(de)(de)ΔAse值(zhi)最(zui)(zui)大，分(fen)(fen)別(bie)為(wei)0.68和(he)0.92.在(zai)整個(ge)凝(ning)(ning)(ning)固(gu)(gu)過(guo)(guo)程中，由(you)于ΔAse與(yu)(yu)ΔAso之和(he)始(shi)終大于零，因而枝晶間殘(can)余(yu)液(ye)相(xiang)中氮(dan)(dan)偏析(xi)對(dui)(dui)(dui)D1 鑄錠凝(ning)(ning)(ning)固(gu)(gu)過(guo)(guo)程中氮(dan)(dan)氣泡(pao)形成(cheng)的(de)(de)影(ying)響大于氮(dan)(dan)溶解(jie)度，起主導作用。此(ci)外，在(zai)整個(ge)凝(ning)(ning)(ning)固(gu)(gu)過(guo)(guo)程中，P8變化趨勢如圖2-62所示，其變化規律(lv)(lv)與(yu)(yu)Young等(deng)。的(de)(de)研究結果一致，Pg的(de)(de)最(zui)(zui)大值(zhi)Pg與(yu)(yu)Ase+Aso的(de)(de)最(zui)(zui)大值(zhi)相(xiang)對(dui)(dui)(dui)應，且在(zai)平衡凝(ning)(ning)(ning)固(gu)(gu)和(he) Scheil 凝(ning)(ning)(ning)固(gu)(gu)過(guo)(guo)程中分(fen)(fen)別(bie)為(wei)0.63MPa和(he)0.62MPa.此(ci)外，可通過(guo)(guo)對(dui)(dui)(dui)比不同鑄錠中的(de)(de)探討凝(ning)(ning)(ning)固(gu)(gu)壓力、初始(shi)氮(dan)(dan)質量分(fen)(fen)數以及合金(jin)元素（鉻和(he)錳）等(deng)對(dui)(dui)(dui)液(ye)相(xiang)中氮(dan)(dan)氣泡(pao)形成(cheng)的(de)(de)影(ying)響，進而明晰各因素對(dui)(dui)(dui)氮(dan)(dan)氣孔形成(cheng)的(de)(de)影(ying)響規律(lv)(lv)。