一、氮氣孔的形(xing)成機理

  在(zai)21.5Cr5Mn1.5Ni0.25N含氮(dan)(dan)(dan)(dan)雙相(xiang)(xiang)鋼凝(ning)固(gu)過(guo)程(cheng)(cheng)中(zhong)(zhong)，氮(dan)(dan)(dan)(dan)氣(qi)(qi)孔形(xing)成(cheng)(cheng)(cheng)和(he)(he)(he)(he)凝(ning)固(gu)前沿處［％N]1iq隨(sui)距離變(bian)化的(de)(de)(de)(de)(de)規(gui)律如(ru)圖(tu)2-55所(suo)(suo)(suo)示(shi)。由于糊(hu)狀(zhuang)區(qu)內大(da)量枝(zhi)晶(jing)網狀(zhuang)結構的(de)(de)(de)(de)(de)形(xing)成(cheng)(cheng)(cheng)，液(ye)相(xiang)(xiang)的(de)(de)(de)(de)(de)對(dui)流只存在(zai)于一(yi)次枝(zhi)晶(jing)尖(jian)端位(wei)置附近。且枝(zhi)晶(jing)間(jian)幾乎無液(ye)相(xiang)(xiang)的(de)(de)(de)(de)(de)流動。因此，枝(zhi)晶(jing)間(jian)殘(can)(can)余液(ye)相(xiang)(xiang)中(zhong)(zhong)的(de)(de)(de)(de)(de)氮(dan)(dan)(dan)(dan)傳質(zhi)主要(yao)依靠氮(dan)(dan)(dan)(dan)的(de)(de)(de)(de)(de)擴散行(xing)為，且糊(hu)狀(zhuang)區(qu)內氮(dan)(dan)(dan)(dan)傳質(zhi)速(su)率(lv)非常小(xiao)(xiao)。初始(shi)相(xiang)(xiang)貧氮(dan)(dan)(dan)(dan)鐵(tie)(tie)素(su)(su)體(ti)(ti)相(xiang)(xiang)8的(de)(de)(de)(de)(de)氮(dan)(dan)(dan)(dan)溶解度和(he)(he)(he)(he)糊(hu)狀(zhuang)區(qu)的(de)(de)(de)(de)(de)氮(dan)(dan)(dan)(dan)傳質(zhi)速(su)率(lv)較低，導(dao)致在(zai)貧氮(dan)(dan)(dan)(dan)鐵(tie)(tie)素(su)(su)體(ti)(ti)相(xiang)(xiang)枝(zhi)晶(jing)附近的(de)(de)(de)(de)(de)液(ye)相(xiang)(xiang)中(zhong)(zhong)出現氮(dan)(dan)(dan)(dan)富集，且［％N]iq迅速(su)增大(da)，如(ru)圖(tu)2-55(a)所(suo)(suo)(suo)示(shi)。根據Yang和(he)(he)(he)(he) Leel70]、Svyazhin 等(deng)、Ridolfi 和(he)(he)(he)(he) Tassal的(de)(de)(de)(de)(de)報道可(ke)知，當［％N]iq的(de)(de)(de)(de)(de)最大(da)值超過(guo)氮(dan)(dan)(dan)(dan)氣(qi)(qi)泡形(xing)成(cheng)(cheng)(cheng)的(de)(de)(de)(de)(de)臨界氮(dan)(dan)(dan)(dan)質(zhi)量分數（［％N]pore)時，該區(qu)域有氣(qi)(qi)泡形(xing)成(cheng)(cheng)(cheng)的(de)(de)(de)(de)(de)可(ke)能性(xing)，如(ru)圖(tu)2-55(b)所(suo)(suo)(suo)示(shi)。在(zai)后(hou)續的(de)(de)(de)(de)(de)凝(ning)固(gu)過(guo)程(cheng)(cheng)中(zhong)(zhong)，隨(sui)著包晶(jing)反應的(de)(de)(de)(de)(de)進行(xing)，富氮(dan)(dan)(dan)(dan)奧氏體(ti)(ti)相(xiang)(xiang)γ以異質(zhi)形(xing)核的(de)(de)(de)(de)(de)方式(shi)在(zai)鐵(tie)(tie)素(su)(su)體(ti)(ti)相(xiang)(xiang)8枝(zhi)晶(jing)的(de)(de)(de)(de)(de)表(biao)面開始(shi)形(xing)核長大(da)，逐漸(jian)包裹鐵(tie)(tie)素(su)(su)體(ti)(ti)相(xiang)(xiang)枝(zhi)晶(jing)表(biao)面，并開始(shi)捕獲(huo)(huo)殘(can)(can)余液(ye)相(xiang)(xiang)中(zhong)(zhong)的(de)(de)(de)(de)(de)氮(dan)(dan)(dan)(dan)氣(qi)(qi)泡，對(dui)比(bi)(bi)圖(tu)2-51和(he)(he)(he)(he)圖(tu)2-56可(ke)知，此時枝(zhi)晶(jing)間(jian)殘(can)(can)余［％N]1ig的(de)(de)(de)(de)(de)增長速(su)率(lv)減小(xiao)(xiao)。對(dui)平衡(heng)凝(ning)固(gu)而言(yan)，殘(can)(can)余液(ye)相(xiang)(xiang)中(zhong)(zhong)氮(dan)(dan)(dan)(dan)氣(qi)(qi)泡形(xing)成(cheng)(cheng)(cheng)以后(hou)，氮(dan)(dan)(dan)(dan)的(de)(de)(de)(de)(de)富集程(cheng)(cheng)度減弱(ruo)，［％N]1iq增長速(su)率(lv)的(de)(de)(de)(de)(de)減小(xiao)(xiao)程(cheng)(cheng)度明顯(xian)；相(xiang)(xiang)比(bi)(bi)之(zhi)下，Scheil凝(ning)固(gu)過(guo)程(cheng)(cheng)中(zhong)(zhong)，氮(dan)(dan)(dan)(dan)氣(qi)(qi)泡形(xing)成(cheng)(cheng)(cheng)以后(hou)，殘(can)(can)余液(ye)相(xiang)(xiang)中(zhong)(zhong)氮(dan)(dan)(dan)(dan)富集狀(zhuang)態(tai)有所(suo)(suo)(suo)緩解，但幅度很小(xiao)(xiao)。隨(sui)著凝(ning)固(gu)界面的(de)(de)(de)(de)(de)進一(yi)步(bu)推移(yi)，被捕獲(huo)(huo)的(de)(de)(de)(de)(de)氮(dan)(dan)(dan)(dan)氣(qi)(qi)泡在(zai)奧氏體(ti)(ti)相(xiang)(xiang)表(biao)面開始(shi)長大(da)，并沿凝(ning)固(gu)方向拉長，如(ru)圖(tu)2-55(c)所(suo)(suo)(suo)示(shi)。

  氮(dan)(dan)(dan)氣(qi)(qi)孔沿(yan)徑向生長，生長方(fang)向與凝(ning)固(gu)方(fang)向一(yi)致(zhi)，那(nei)么氮(dan)(dan)(dan)氣(qi)(qi)孔初始(shi)形(xing)成(cheng)位置靠近鑄錠(ding)邊部，且氮(dan)(dan)(dan)氣(qi)(qi)泡(pao)(pao)初始(shi)位置邊緣全(quan)由奧氏體相γ構成(cheng)（圖2-57中I區），與圖2-55描述相符。隨(sui)著氮(dan)(dan)(dan)氣(qi)(qi)孔被拉長，鐵素體相和奧氏體相以體積分數比約(yue)為0.92的(de)(de)關系交替(ti)在氮(dan)(dan)(dan)氣(qi)(qi)泡(pao)(pao)周圍形(xing)成(cheng)，直到(dao)氮(dan)(dan)(dan)氣(qi)(qi)孔閉合。凝(ning)固(gu)結束后，氮(dan)(dan)(dan)氣(qi)(qi)孔的(de)(de)宏觀形(xing)貌類似于(yu)橢(tuo)圓形(xing)，與Wei等(deng)的(de)(de)研究(jiu)結果一(yi)致(zhi)

二、氮微觀偏析(xi)對氮氣(qi)孔的(de)影響(xiang)

  氮(dan)(dan)(dan)(dan)(dan)的(de)(de)(de)(de)分(fen)配系數(shu)較(jiao)(jiao)小(xiao)，導(dao)致液(ye)相(xiang)向固(gu)(gu)相(xiang)轉(zhuan)變的(de)(de)(de)(de)過(guo)程中(zhong)(zhong)，固(gu)(gu)相(xiang)會將(jiang)(jiang)多余的(de)(de)(de)(de)氮(dan)(dan)(dan)(dan)(dan)轉(zhuan)移到殘(can)余液(ye)相(xiang)中(zhong)(zhong)，形(xing)成氮(dan)(dan)(dan)(dan)(dan)偏(pian)(pian)析(xi)。在(zai)氮(dan)(dan)(dan)(dan)(dan)偏(pian)(pian)析(xi)程度逐漸加重的(de)(de)(de)(de)過(guo)程中(zhong)(zhong)，當(dang)殘(can)余液(ye)相(xiang)中(zhong)(zhong)氮(dan)(dan)(dan)(dan)(dan)質(zhi)量分(fen)數(shu)超過(guo)其(qi)飽和度時(shi)，極(ji)易(yi)(yi)形(xing)成氮(dan)(dan)(dan)(dan)(dan)氣(qi)(qi)泡(pao)。隨著(zhu)凝固(gu)(gu)的(de)(de)(de)(de)進行，若氣(qi)(qi)泡(pao)無法上浮而被捕獲，凝固(gu)(gu)結(jie)束后就會在(zai)鑄(zhu)錠內部形(xing)成氣(qi)(qi)孔(kong)(kong)。因(yin)此，凝固(gu)(gu)過(guo)程中(zhong)(zhong)氮(dan)(dan)(dan)(dan)(dan)偏(pian)(pian)析(xi)和溶解度對(dui)鑄(zhu)錠中(zhong)(zhong)最(zui)終氮(dan)(dan)(dan)(dan)(dan)氣(qi)(qi)孔(kong)(kong)的(de)(de)(de)(de)形(xing)成有至關重要(yao)的(de)(de)(de)(de)作用。氮(dan)(dan)(dan)(dan)(dan)氣(qi)(qi)孔(kong)(kong)多數(shu)情(qing)況下與疏松縮(suo)孔(kong)(kong)共存(cun)，內壁凹凸不平呈(cheng)現裂紋狀，且整個氣(qi)(qi)孔(kong)(kong)形(xing)狀不規則，如圖2-58所示。此類氣(qi)(qi)孔(kong)(kong)不僅與鋼(gang)液(ye)中(zhong)(zhong)氣(qi)(qi)泡(pao)的(de)(de)(de)(de)形(xing)成有關，還受凝固(gu)(gu)收縮(suo)等(deng)(deng)因(yin)素的(de)(de)(de)(de)影響，且多數(shu)分(fen)布于鑄(zhu)錠心部，尤其(qi)在(zai)中(zhong)(zhong)心等(deng)(deng)軸晶區。這(zhe)主要(yao)由于中(zhong)(zhong)心等(deng)(deng)軸晶區內枝晶生長較(jiao)(jiao)發達，容易(yi)(yi)形(xing)成復雜(za)的(de)(de)(de)(de)網狀結(jie)構，從(cong)(cong)(cong)而將(jiang)(jiang)液(ye)相(xiang)分(fen)割成無數(shu)個獨立的(de)(de)(de)(de)液(ye)相(xiang)區域，當(dang)發生凝固(gu)(gu)收縮(suo)時(shi)，難以進行補縮(suo)，在(zai)形(xing)成疏松縮(suo)孔(kong)(kong)的(de)(de)(de)(de)同(tong)時(shi)，局部鋼(gang)液(ye)靜壓力降低，促(cu)使氮(dan)(dan)(dan)(dan)(dan)從(cong)(cong)(cong)殘(can)余液(ye)相(xiang)中(zhong)(zhong)析(xi)出，從(cong)(cong)(cong)而形(xing)成了氮(dan)(dan)(dan)(dan)(dan)氣(qi)(qi)孔(kong)(kong)和疏松縮(suo)孔(kong)(kong)共存(cun)的(de)(de)(de)(de)宏(hong)觀(guan)缺陷。

  平衡(heng)凝固時(shi)，19Cr14Mn0.9N含(han)氮(dan)(dan)(dan)奧氏(shi)(shi)體(ti)(ti)不銹鋼殘余液相(xiang)(xiang)中(zhong)氮(dan)(dan)(dan)偏(pian)析(xi)與(yu)體(ti)(ti)系(xi)氮(dan)(dan)(dan)溶解度的(de)差(cha)值(zhi)如圖2-59所示。凝固初期鐵素(su)體(ti)(ti)阱（ferrite trap)的(de)形成，導(dao)致(zhi)氮(dan)(dan)(dan)溶解度的(de)降低，進而(er)使氮(dan)(dan)(dan)偏(pian)析(xi)與(yu)體(ti)(ti)系(xi)氮(dan)(dan)(dan)溶解度差(cha)值(zhi)呈現出略微增(zeng)大的(de)趨勢。但在(zai)(zai)后續凝固過程中(zhong)，隨著鐵素(su)體(ti)(ti)阱的(de)消失以及富氮(dan)(dan)(dan)奧氏(shi)(shi)體(ti)(ti)相(xiang)(xiang)的(de)不斷形成，差(cha)值(zhi)減(jian)小(xiao)(xiao)；在(zai)(zai)整個凝固過程中(zhong)差(cha)值(zhi)始終較小(xiao)(xiao)，且變化幅度較窄。對于(yu)19Cr14Mn0.9N 含(han)氮(dan)(dan)(dan)奧氏(shi)(shi)體(ti)(ti)不銹鋼，液相(xiang)(xiang)中(zhong)氮(dan)(dan)(dan)氣泡的(de)形成趨勢較小(xiao)(xiao)，難以在(zai)(zai)鑄錠內形成獨立(li)內壁光滑的(de)規則(ze)氮(dan)(dan)(dan)氣孔。

  此外，目前有人對(dui)(dui)奧氏體鋼(gang)(gang)凝(ning)(ning)固(gu)(gu)過(guo)(guo)程(cheng)中(zhong)(zhong)(zhong)氮(dan)(dan)(dan)氣孔(kong)(kong)的(de)(de)形成進(jin)行了(le)(le)(le)大(da)量(liang)研究，如Yang和(he)Leel901研究了(le)(le)(le)奧氏體鋼(gang)(gang)16Cr3NixMn(x=9和(he)11)凝(ning)(ning)固(gu)(gu)過(guo)(guo)程(cheng)中(zhong)(zhong)(zhong)壓力和(he)初始氮(dan)(dan)(dan)質量(liang)分數等因素對(dui)(dui)氮(dan)(dan)(dan)氣孔(kong)(kong)形成的(de)(de)影響(xiang)規(gui)律(lv)，并(bing)建立了(le)(le)(le)相應的(de)(de)預測模型。Ridolfi和(he)Tassal[84]分析(xi)了(le)(le)(le)氮(dan)(dan)(dan)偏析(xi)、合金元(yuan)素、冷(leng)卻(que)速率以及枝(zhi)晶間距對(dui)(dui)奧氏體鋼(gang)(gang)中(zhong)(zhong)(zhong)氮(dan)(dan)(dan)氣孔(kong)(kong)的(de)(de)影響(xiang)規(gui)律(lv)，并(bing)揭示了(le)(le)(le)奧氏體鋼(gang)(gang)中(zhong)(zhong)(zhong)氮(dan)(dan)(dan)氣孔(kong)(kong)形成機(ji)理。然而，目前對(dui)(dui)于(yu)雙(shuang)(shuang)相鋼(gang)(gang)中(zhong)(zhong)(zhong)氮(dan)(dan)(dan)氣孔(kong)(kong)形成的(de)(de)研究較少(shao)，且主(zhu)要集中(zhong)(zhong)(zhong)在合金元(yuan)素、鑄造方(fang)式、冷(leng)卻(que)速率等因素對(dui)(dui)氮(dan)(dan)(dan)氣孔(kong)(kong)影響(xiang)規(gui)律(lv)的(de)(de)研究，鮮有對(dui)(dui)雙(shuang)(shuang)相鋼(gang)(gang)中(zhong)(zhong)(zhong)氮(dan)(dan)(dan)氣孔(kong)(kong)形成機(ji)理的(de)(de)報道。以21.5Cr5Mn1.5Ni0.25N含(han)(han)氮(dan)(dan)(dan)雙(shuang)(shuang)相鋼(gang)(gang)為(wei)例，氮(dan)(dan)(dan)偏析(xi)與溶(rong)(rong)解度的(de)(de)差(cha)(cha)值在整(zheng)個凝(ning)(ning)固(gu)(gu)過(guo)(guo)程(cheng)中(zhong)(zhong)(zhong)的(de)(de)變化趨勢，如圖2-59所示。隨著凝(ning)(ning)固(gu)(gu)的(de)(de)進(jin)行，氮(dan)(dan)(dan)偏析(xi)始終大(da)于(yu)氮(dan)(dan)(dan)溶(rong)(rong)解度，且差(cha)(cha)值呈現出(chu)快速增大(da)的(de)(de)趨勢。因此，在21.5Cr5Mn1.5Ni0.25N 含(han)(han)氮(dan)(dan)(dan)雙(shuang)(shuang)相鋼(gang)(gang)凝(ning)(ning)固(gu)(gu)過(guo)(guo)程(cheng)中(zhong)(zhong)(zhong)，氮(dan)(dan)(dan)偏析(xi)嚴重，殘余(yu)液相內氮(dan)(dan)(dan)氣泡形成趨勢較大(da)，明顯(xian)高(gao)于(yu)19Cr14Mn0.9N含(han)(han)氮(dan)(dan)(dan)奧氏體不銹鋼(gang)(gang)。

  氮(dan)氣泡(pao)形成和長(chang)大具(ju)有(you)重要的(de)作用（圖2-60).其(qi)中，σ為氣液界面的(de)表面張(zhang)力，r為氣泡(pao)半徑。結合(he)經典形核理(li)論，氮(dan)氣泡(pao)在鋼液中穩定存在的(de)必要條件為氣泡(pao)內壓(ya)力大于作用于氣泡(pao)的(de)所(suo)有(you)壓(ya)力之和，即

  式(shi)中(zhong)，Aso由凝固(gu)過(guo)程(cheng)中(zhong)除(chu)氮(dan)(dan)以外(wai)其(qi)他(ta)合金元(yuan)素的(de)微觀偏析(xi)(xi)進行計(ji)(ji)算(suan)，其(qi)值(zhi)隨著(zhu)枝(zhi)晶間(jian)殘(can)余液(ye)(ye)相(xiang)中(zhong)氮(dan)(dan)溶(rong)解度(du)的(de)增加而減(jian)小，表征了(le)枝(zhi)晶間(jian)殘(can)余液(ye)(ye)相(xiang)中(zhong)氮(dan)(dan)溶(rong)解度(du)對氮(dan)(dan)氣泡形成的(de)影響(xiang)程(cheng)度(du)；Ase表征了(le)枝(zhi)晶間(jian)氮(dan)(dan)偏析(xi)(xi)對氮(dan)(dan)氣泡形成的(de)影響(xiang)程(cheng)度(du)，可由凝固(gu)過(guo)程(cheng)中(zhong)枝(zhi)晶間(jian)殘(can)余液(ye)(ye)相(xiang)中(zhong)氮(dan)(dan)偏析(xi)(xi)計(ji)(ji)算(suan)獲得(de)，其(qi)值(zhi)隨著(zhu)氮(dan)(dan)偏析(xi)(xi)的(de)增大而增大。此(ci)外(wai)，用于計(ji)(ji)算(suan)Aso和(he)Ase時所(suo)需的(de)合金元(yuan)素偏析(xi)(xi)均由鋼(gang)凝固(gu)相(xiang)變(bian)所(suo)致(zhi)。

  氮氣(qi)泡(pao)的(de)(de)(de)(de)形(xing)核和(he)長(chang)大(da)過(guo)程(cheng)(cheng)(cheng)復雜，且影響因(yin)(yin)素(su)眾多，包(bao)括凝(ning)(ning)固(gu)(gu)(gu)收縮(suo)、冶煉環境(jing)以及坩堝材質(zhi)(zhi)(zhi)等(deng)(deng)。因(yin)(yin)此，很難(nan)采用Pg值(zhi)精確(que)預測凝(ning)(ning)固(gu)(gu)(gu)過(guo)程(cheng)(cheng)(cheng)中(zhong)氮氣(qi)泡(pao)的(de)(de)(de)(de)形(xing)成(cheng)和(he)長(chang)大(da)。然而(er)基于Yang等(deng)(deng)的(de)(de)(de)(de)實(shi)(shi)驗研究［70,77],在(zai)評估凝(ning)(ning)固(gu)(gu)(gu)壓力(li)、合金成(cheng)分等(deng)(deng)因(yin)(yin)素(su)對氮氣(qi)泡(pao)形(xing)成(cheng)的(de)(de)(de)(de)影響程(cheng)(cheng)(cheng)度時，Pg起關鍵作用。實(shi)(shi)際(ji)凝(ning)(ning)固(gu)(gu)(gu)過(guo)程(cheng)(cheng)(cheng)介于平(ping)(ping)衡凝(ning)(ning)固(gu)(gu)(gu)（固(gu)(gu)(gu)／液相(xiang)中(zhong)溶質(zhi)(zhi)(zhi)完全擴散）和(he)Scheil凝(ning)(ning)固(gu)(gu)(gu)（固(gu)(gu)(gu)相(xiang)無溶質(zhi)(zhi)(zhi)擴散，液相(xiang)中(zhong)完全擴散）之間70].因(yin)(yin)此，可(ke)分別計算(suan)平(ping)(ping)衡凝(ning)(ning)固(gu)(gu)(gu)和(he)Scheil凝(ning)(ning)固(gu)(gu)(gu)過(guo)程(cheng)(cheng)(cheng)中(zhong)的(de)(de)(de)(de)Aso、Ase和(he)Pg,闡(chan)明實(shi)(shi)際(ji)凝(ning)(ning)固(gu)(gu)(gu)過(guo)程(cheng)(cheng)(cheng)中(zhong)壓力(li)等(deng)(deng)因(yin)(yin)素(su)對氮氣(qi)泡(pao)形(xing)成(cheng)的(de)(de)(de)(de)影響規律。

  現以21.5Cr5Mn1.5Ni0.25N含氮雙相(xiang)鋼D1鑄錠為例，對(dui)凝固過程中Aso、Ase和(he)P8的(de)(de)變(bian)化(hua)趨勢進(jin)行計算。圖2-61描(miao)述了(le)ΔAso(=Asa-Aso,0)和(he)AAse(=Ase-Ase,o)隨固相(xiang)質量分數的(de)(de)變(bian)化(hua)趨勢（Aso,0和(he)Asc,0分別(bie)為D1鑄錠凝固時Aso和(he)Ase的(de)(de)初(chu)始值(zhi)）。

  在平(ping)衡凝(ning)(ning)固和Scheil凝(ning)(ning)固過程中(zhong)(zhong)(zhong)，ΔAso的(de)最小值(zhi)分別為－0.145和－0.397,與(yu)此(ci)相對(dui)(dui)應的(de)ΔAse值(zhi)最大，分別為0.68和0.92.在整(zheng)個凝(ning)(ning)固過程中(zhong)(zhong)(zhong)，由于(yu)ΔAse與(yu)ΔAso之和始終大于(yu)零，因而枝晶間(jian)殘余液相中(zhong)(zhong)(zhong)氮偏析對(dui)(dui)D1 鑄(zhu)(zhu)錠凝(ning)(ning)固過程中(zhong)(zhong)(zhong)氮氣泡形(xing)成(cheng)的(de)影(ying)(ying)響大于(yu)氮溶解(jie)度(du)，起主(zhu)導作(zuo)用。此(ci)外(wai)(wai)，在整(zheng)個凝(ning)(ning)固過程中(zhong)(zhong)(zhong)，P8變(bian)化趨勢如圖2-62所示，其(qi)變(bian)化規(gui)律與(yu)Young等(deng)。的(de)研究結果一致，Pg的(de)最大值(zhi)Pg與(yu)Ase+Aso的(de)最大值(zhi)相對(dui)(dui)應，且在平(ping)衡凝(ning)(ning)固和 Scheil 凝(ning)(ning)固過程中(zhong)(zhong)(zhong)分別為0.63MPa和0.62MPa.此(ci)外(wai)(wai)，可通過對(dui)(dui)比不(bu)同鑄(zhu)(zhu)錠中(zhong)(zhong)(zhong)的(de)探(tan)討凝(ning)(ning)固壓力、初始氮質量分數以及合金元(yuan)素(su)（鉻(ge)和錳）等(deng)對(dui)(dui)液相中(zhong)(zhong)(zhong)氮氣泡形(xing)成(cheng)的(de)影(ying)(ying)響，進(jin)而明晰各因素(su)對(dui)(dui)氮氣孔形(xing)成(cheng)的(de)影(ying)(ying)響規(gui)律。