一、氮氣(qi)孔的形成機理(li)

  在(zai)21.5Cr5Mn1.5Ni0.25N含(han)氮(dan)(dan)(dan)雙(shuang)相(xiang)(xiang)(xiang)鋼(gang)凝(ning)(ning)固(gu)過(guo)程中(zhong)，氮(dan)(dan)(dan)氣(qi)孔形(xing)成(cheng)(cheng)和(he)凝(ning)(ning)固(gu)前(qian)沿處［％N]1iq隨(sui)(sui)距離變(bian)化的(de)(de)(de)(de)規(gui)律如(ru)圖(tu)2-55所示(shi)。由于糊狀(zhuang)區內(nei)大(da)(da)量枝(zhi)(zhi)晶(jing)(jing)(jing)網狀(zhuang)結構的(de)(de)(de)(de)形(xing)成(cheng)(cheng)，液(ye)(ye)相(xiang)(xiang)(xiang)的(de)(de)(de)(de)對流只存在(zai)于一次枝(zhi)(zhi)晶(jing)(jing)(jing)尖端(duan)位置(zhi)附近。且枝(zhi)(zhi)晶(jing)(jing)(jing)間幾(ji)乎無液(ye)(ye)相(xiang)(xiang)(xiang)的(de)(de)(de)(de)流動。因此，枝(zhi)(zhi)晶(jing)(jing)(jing)間殘(can)余液(ye)(ye)相(xiang)(xiang)(xiang)中(zhong)的(de)(de)(de)(de)氮(dan)(dan)(dan)傳(chuan)(chuan)質(zhi)主要依(yi)靠(kao)氮(dan)(dan)(dan)的(de)(de)(de)(de)擴(kuo)散(san)行(xing)為，且糊狀(zhuang)區內(nei)氮(dan)(dan)(dan)傳(chuan)(chuan)質(zhi)速(su)率非常小(xiao)。初始相(xiang)(xiang)(xiang)貧氮(dan)(dan)(dan)鐵素體(ti)相(xiang)(xiang)(xiang)8的(de)(de)(de)(de)氮(dan)(dan)(dan)溶解(jie)度和(he)糊狀(zhuang)區的(de)(de)(de)(de)氮(dan)(dan)(dan)傳(chuan)(chuan)質(zhi)速(su)率較低，導致在(zai)貧氮(dan)(dan)(dan)鐵素體(ti)相(xiang)(xiang)(xiang)枝(zhi)(zhi)晶(jing)(jing)(jing)附近的(de)(de)(de)(de)液(ye)(ye)相(xiang)(xiang)(xiang)中(zhong)出現氮(dan)(dan)(dan)富(fu)(fu)(fu)集，且［％N]iq迅速(su)增(zeng)(zeng)大(da)(da)，如(ru)圖(tu)2-55(a)所示(shi)。根據Yang和(he) Leel70]、Svyazhin 等、Ridolfi 和(he) Tassal的(de)(de)(de)(de)報道可知，當(dang)［％N]iq的(de)(de)(de)(de)最大(da)(da)值超過(guo)氮(dan)(dan)(dan)氣(qi)泡(pao)形(xing)成(cheng)(cheng)的(de)(de)(de)(de)臨界氮(dan)(dan)(dan)質(zhi)量分數（［％N]pore)時，該區域有(you)氣(qi)泡(pao)形(xing)成(cheng)(cheng)的(de)(de)(de)(de)可能(neng)性，如(ru)圖(tu)2-55(b)所示(shi)。在(zai)后續(xu)的(de)(de)(de)(de)凝(ning)(ning)固(gu)過(guo)程中(zhong)，隨(sui)(sui)著包晶(jing)(jing)(jing)反應的(de)(de)(de)(de)進行(xing)，富(fu)(fu)(fu)氮(dan)(dan)(dan)奧(ao)氏體(ti)相(xiang)(xiang)(xiang)γ以異(yi)質(zhi)形(xing)核的(de)(de)(de)(de)方式(shi)在(zai)鐵素體(ti)相(xiang)(xiang)(xiang)8枝(zhi)(zhi)晶(jing)(jing)(jing)的(de)(de)(de)(de)表(biao)面(mian)開始形(xing)核長(chang)大(da)(da)，逐漸(jian)包裹鐵素體(ti)相(xiang)(xiang)(xiang)枝(zhi)(zhi)晶(jing)(jing)(jing)表(biao)面(mian)，并開始捕獲殘(can)余液(ye)(ye)相(xiang)(xiang)(xiang)中(zhong)的(de)(de)(de)(de)氮(dan)(dan)(dan)氣(qi)泡(pao)，對比(bi)圖(tu)2-51和(he)圖(tu)2-56可知，此時枝(zhi)(zhi)晶(jing)(jing)(jing)間殘(can)余［％N]1ig的(de)(de)(de)(de)增(zeng)(zeng)長(chang)速(su)率減小(xiao)。對平(ping)衡凝(ning)(ning)固(gu)而言，殘(can)余液(ye)(ye)相(xiang)(xiang)(xiang)中(zhong)氮(dan)(dan)(dan)氣(qi)泡(pao)形(xing)成(cheng)(cheng)以后，氮(dan)(dan)(dan)的(de)(de)(de)(de)富(fu)(fu)(fu)集程度減弱，［％N]1iq增(zeng)(zeng)長(chang)速(su)率的(de)(de)(de)(de)減小(xiao)程度明(ming)顯(xian)；相(xiang)(xiang)(xiang)比(bi)之下，Scheil凝(ning)(ning)固(gu)過(guo)程中(zhong)，氮(dan)(dan)(dan)氣(qi)泡(pao)形(xing)成(cheng)(cheng)以后，殘(can)余液(ye)(ye)相(xiang)(xiang)(xiang)中(zhong)氮(dan)(dan)(dan)富(fu)(fu)(fu)集狀(zhuang)態有(you)所緩解(jie)，但(dan)幅度很小(xiao)。隨(sui)(sui)著凝(ning)(ning)固(gu)界面(mian)的(de)(de)(de)(de)進一步(bu)推移，被捕獲的(de)(de)(de)(de)氮(dan)(dan)(dan)氣(qi)泡(pao)在(zai)奧(ao)氏體(ti)相(xiang)(xiang)(xiang)表(biao)面(mian)開始長(chang)大(da)(da)，并沿凝(ning)(ning)固(gu)方向拉長(chang)，如(ru)圖(tu)2-55(c)所示(shi)。

  氮(dan)氣孔(kong)沿徑向(xiang)生長，生長方向(xiang)與凝固方向(xiang)一致，那么氮(dan)氣孔(kong)初始形成位(wei)置靠近鑄錠(ding)邊(bian)部，且氮(dan)氣泡初始位(wei)置邊(bian)緣全由奧(ao)氏體(ti)相γ構成（圖(tu)2-57中I區），與圖(tu)2-55描述相符。隨著氮(dan)氣孔(kong)被拉長，鐵素體(ti)相和奧(ao)氏體(ti)相以體(ti)積分數(shu)比約為0.92的關(guan)系交替在(zai)氮(dan)氣泡周圍(wei)形成，直到氮(dan)氣孔(kong)閉合。凝固結(jie)束后，氮(dan)氣孔(kong)的宏(hong)觀形貌類似于橢圓形，與Wei等的研(yan)究結(jie)果(guo)一致

二、氮微觀偏析對氮氣孔(kong)的影(ying)響

  氮的(de)(de)(de)(de)(de)分(fen)(fen)(fen)配系數較(jiao)小(xiao)，導(dao)致液(ye)(ye)(ye)(ye)相(xiang)向固相(xiang)轉變的(de)(de)(de)(de)(de)過程(cheng)(cheng)(cheng)中(zhong)(zhong)，固相(xiang)會(hui)將多余(yu)的(de)(de)(de)(de)(de)氮轉移到殘余(yu)液(ye)(ye)(ye)(ye)相(xiang)中(zhong)(zhong)，形(xing)(xing)(xing)成(cheng)(cheng)氮偏(pian)析(xi)。在(zai)氮偏(pian)析(xi)程(cheng)(cheng)(cheng)度(du)逐漸加重(zhong)的(de)(de)(de)(de)(de)過程(cheng)(cheng)(cheng)中(zhong)(zhong)，當殘余(yu)液(ye)(ye)(ye)(ye)相(xiang)中(zhong)(zhong)氮質量分(fen)(fen)(fen)數超過其飽(bao)和(he)(he)度(du)時(shi)，極易形(xing)(xing)(xing)成(cheng)(cheng)氮氣(qi)(qi)泡(pao)。隨(sui)著凝(ning)(ning)固的(de)(de)(de)(de)(de)進(jin)(jin)行，若氣(qi)(qi)泡(pao)無(wu)法上(shang)浮而(er)(er)被捕(bu)獲，凝(ning)(ning)固結束后就會(hui)在(zai)鑄錠(ding)(ding)內部(bu)形(xing)(xing)(xing)成(cheng)(cheng)氣(qi)(qi)孔(kong)(kong)。因(yin)此，凝(ning)(ning)固過程(cheng)(cheng)(cheng)中(zhong)(zhong)氮偏(pian)析(xi)和(he)(he)溶解度(du)對鑄錠(ding)(ding)中(zhong)(zhong)最終氮氣(qi)(qi)孔(kong)(kong)的(de)(de)(de)(de)(de)形(xing)(xing)(xing)成(cheng)(cheng)有至關重(zhong)要的(de)(de)(de)(de)(de)作用。氮氣(qi)(qi)孔(kong)(kong)多數情(qing)況下與(yu)疏(shu)松縮(suo)孔(kong)(kong)共存，內壁凹(ao)凸不平(ping)呈現裂(lie)紋狀(zhuang)，且(qie)整個氣(qi)(qi)孔(kong)(kong)形(xing)(xing)(xing)狀(zhuang)不規則，如圖2-58所(suo)示。此類(lei)氣(qi)(qi)孔(kong)(kong)不僅與(yu)鋼(gang)液(ye)(ye)(ye)(ye)中(zhong)(zhong)氣(qi)(qi)泡(pao)的(de)(de)(de)(de)(de)形(xing)(xing)(xing)成(cheng)(cheng)有關，還受凝(ning)(ning)固收縮(suo)等(deng)(deng)(deng)因(yin)素的(de)(de)(de)(de)(de)影響(xiang)，且(qie)多數分(fen)(fen)(fen)布(bu)于鑄錠(ding)(ding)心(xin)部(bu)，尤其在(zai)中(zhong)(zhong)心(xin)等(deng)(deng)(deng)軸晶(jing)區(qu)(qu)。這(zhe)主要由(you)于中(zhong)(zhong)心(xin)等(deng)(deng)(deng)軸晶(jing)區(qu)(qu)內枝晶(jing)生(sheng)長較(jiao)發達，容易形(xing)(xing)(xing)成(cheng)(cheng)復雜(za)的(de)(de)(de)(de)(de)網狀(zhuang)結構，從(cong)而(er)(er)將液(ye)(ye)(ye)(ye)相(xiang)分(fen)(fen)(fen)割成(cheng)(cheng)無(wu)數個獨立的(de)(de)(de)(de)(de)液(ye)(ye)(ye)(ye)相(xiang)區(qu)(qu)域(yu)，當發生(sheng)凝(ning)(ning)固收縮(suo)時(shi)，難(nan)以進(jin)(jin)行補縮(suo)，在(zai)形(xing)(xing)(xing)成(cheng)(cheng)疏(shu)松縮(suo)孔(kong)(kong)的(de)(de)(de)(de)(de)同(tong)時(shi)，局部(bu)鋼(gang)液(ye)(ye)(ye)(ye)靜(jing)壓力降(jiang)低(di)，促使(shi)氮從(cong)殘余(yu)液(ye)(ye)(ye)(ye)相(xiang)中(zhong)(zhong)析(xi)出，從(cong)而(er)(er)形(xing)(xing)(xing)成(cheng)(cheng)了氮氣(qi)(qi)孔(kong)(kong)和(he)(he)疏(shu)松縮(suo)孔(kong)(kong)共存的(de)(de)(de)(de)(de)宏觀(guan)缺(que)陷。

  平(ping)衡(heng)凝固時，19Cr14Mn0.9N含(han)氮(dan)(dan)(dan)(dan)奧氏體(ti)(ti)不銹鋼(gang)殘余液(ye)相(xiang)中(zhong)(zhong)氮(dan)(dan)(dan)(dan)偏析與體(ti)(ti)系(xi)氮(dan)(dan)(dan)(dan)溶解度的差(cha)(cha)值如圖2-59所示。凝固初(chu)期鐵(tie)素體(ti)(ti)阱(jing)（ferrite trap)的形(xing)成(cheng)，導致氮(dan)(dan)(dan)(dan)溶解度的降低，進而使(shi)氮(dan)(dan)(dan)(dan)偏析與體(ti)(ti)系(xi)氮(dan)(dan)(dan)(dan)溶解度差(cha)(cha)值呈(cheng)現出(chu)略微(wei)增大的趨勢。但(dan)在(zai)后續凝固過程(cheng)中(zhong)(zhong)，隨著(zhu)鐵(tie)素體(ti)(ti)阱(jing)的消(xiao)失以及富氮(dan)(dan)(dan)(dan)奧氏體(ti)(ti)相(xiang)的不斷形(xing)成(cheng)，差(cha)(cha)值減小；在(zai)整個(ge)凝固過程(cheng)中(zhong)(zhong)差(cha)(cha)值始終較小，且變(bian)化(hua)幅度較窄(zhai)。對于19Cr14Mn0.9N 含(han)氮(dan)(dan)(dan)(dan)奧氏體(ti)(ti)不銹鋼(gang)，液(ye)相(xiang)中(zhong)(zhong)氮(dan)(dan)(dan)(dan)氣(qi)泡的形(xing)成(cheng)趨勢較小，難(nan)以在(zai)鑄錠(ding)內形(xing)成(cheng)獨立內壁光滑(hua)的規則(ze)氮(dan)(dan)(dan)(dan)氣(qi)孔。

  此(ci)外，目前有(you)人對(dui)(dui)(dui)奧(ao)(ao)氏(shi)體(ti)鋼(gang)(gang)(gang)(gang)凝(ning)固過(guo)(guo)程(cheng)中(zhong)(zhong)氮(dan)(dan)(dan)(dan)(dan)氣(qi)(qi)孔(kong)的(de)(de)形(xing)成進行了大量研究(jiu)，如Yang和(he)(he)Leel901研究(jiu)了奧(ao)(ao)氏(shi)體(ti)鋼(gang)(gang)(gang)(gang)16Cr3NixMn(x=9和(he)(he)11)凝(ning)固過(guo)(guo)程(cheng)中(zhong)(zhong)壓力和(he)(he)初始(shi)氮(dan)(dan)(dan)(dan)(dan)質量分數等(deng)因素(su)對(dui)(dui)(dui)氮(dan)(dan)(dan)(dan)(dan)氣(qi)(qi)孔(kong)形(xing)成的(de)(de)影響(xiang)(xiang)規律(lv)，并(bing)建立(li)了相應的(de)(de)預測模型。Ridolfi和(he)(he)Tassal[84]分析了氮(dan)(dan)(dan)(dan)(dan)偏(pian)析、合(he)金元素(su)、冷卻速(su)率(lv)以及枝晶間(jian)距對(dui)(dui)(dui)奧(ao)(ao)氏(shi)體(ti)鋼(gang)(gang)(gang)(gang)中(zhong)(zhong)氮(dan)(dan)(dan)(dan)(dan)氣(qi)(qi)孔(kong)的(de)(de)影響(xiang)(xiang)規律(lv)，并(bing)揭示(shi)了奧(ao)(ao)氏(shi)體(ti)鋼(gang)(gang)(gang)(gang)中(zhong)(zhong)氮(dan)(dan)(dan)(dan)(dan)氣(qi)(qi)孔(kong)形(xing)成機(ji)理(li)。然而，目前對(dui)(dui)(dui)于雙相鋼(gang)(gang)(gang)(gang)中(zhong)(zhong)氮(dan)(dan)(dan)(dan)(dan)氣(qi)(qi)孔(kong)形(xing)成的(de)(de)研究(jiu)較少，且主要集(ji)中(zhong)(zhong)在(zai)(zai)合(he)金元素(su)、鑄造(zao)方式(shi)、冷卻速(su)率(lv)等(deng)因素(su)對(dui)(dui)(dui)氮(dan)(dan)(dan)(dan)(dan)氣(qi)(qi)孔(kong)影響(xiang)(xiang)規律(lv)的(de)(de)研究(jiu)，鮮(xian)有(you)對(dui)(dui)(dui)雙相鋼(gang)(gang)(gang)(gang)中(zhong)(zhong)氮(dan)(dan)(dan)(dan)(dan)氣(qi)(qi)孔(kong)形(xing)成機(ji)理(li)的(de)(de)報道。以21.5Cr5Mn1.5Ni0.25N含(han)氮(dan)(dan)(dan)(dan)(dan)雙相鋼(gang)(gang)(gang)(gang)為(wei)例，氮(dan)(dan)(dan)(dan)(dan)偏(pian)析與溶(rong)解(jie)(jie)度的(de)(de)差(cha)值(zhi)在(zai)(zai)整個(ge)凝(ning)固過(guo)(guo)程(cheng)中(zhong)(zhong)的(de)(de)變化(hua)趨(qu)勢，如圖2-59所示(shi)。隨著凝(ning)固的(de)(de)進行，氮(dan)(dan)(dan)(dan)(dan)偏(pian)析始(shi)終大于氮(dan)(dan)(dan)(dan)(dan)溶(rong)解(jie)(jie)度，且差(cha)值(zhi)呈現出快速(su)增大的(de)(de)趨(qu)勢。因此(ci)，在(zai)(zai)21.5Cr5Mn1.5Ni0.25N 含(han)氮(dan)(dan)(dan)(dan)(dan)雙相鋼(gang)(gang)(gang)(gang)凝(ning)固過(guo)(guo)程(cheng)中(zhong)(zhong)，氮(dan)(dan)(dan)(dan)(dan)偏(pian)析嚴重(zhong)，殘余液相內氮(dan)(dan)(dan)(dan)(dan)氣(qi)(qi)泡形(xing)成趨(qu)勢較大，明顯高于19Cr14Mn0.9N含(han)氮(dan)(dan)(dan)(dan)(dan)奧(ao)(ao)氏(shi)體(ti)不銹鋼(gang)(gang)(gang)(gang)。

  氮(dan)氣(qi)泡(pao)(pao)(pao)形成(cheng)和長大具(ju)有重(zhong)要的(de)作(zuo)用（圖2-60).其(qi)中，σ為(wei)(wei)氣(qi)液(ye)界面的(de)表面張力(li)，r為(wei)(wei)氣(qi)泡(pao)(pao)(pao)半(ban)徑。結合經(jing)典(dian)形核理論，氮(dan)氣(qi)泡(pao)(pao)(pao)在(zai)(zai)鋼液(ye)中穩定存在(zai)(zai)的(de)必要條件為(wei)(wei)氣(qi)泡(pao)(pao)(pao)內壓力(li)大于作(zuo)用于氣(qi)泡(pao)(pao)(pao)的(de)所有壓力(li)之和，即

  式中，Aso由(you)凝固過程(cheng)(cheng)中除氮以外其(qi)他(ta)合金元(yuan)素的微(wei)觀偏(pian)析進行計(ji)算(suan)，其(qi)值(zhi)隨(sui)著枝晶(jing)間殘(can)余(yu)液相(xiang)中氮溶解度(du)的增加而減小，表征了枝晶(jing)間殘(can)余(yu)液相(xiang)中氮溶解度(du)對氮氣(qi)泡(pao)形成的影(ying)(ying)響程(cheng)(cheng)度(du)；Ase表征了枝晶(jing)間氮偏(pian)析對氮氣(qi)泡(pao)形成的影(ying)(ying)響程(cheng)(cheng)度(du)，可由(you)凝固過程(cheng)(cheng)中枝晶(jing)間殘(can)余(yu)液相(xiang)中氮偏(pian)析計(ji)算(suan)獲(huo)得，其(qi)值(zhi)隨(sui)著氮偏(pian)析的增大(da)而增大(da)。此外，用于計(ji)算(suan)Aso和(he)Ase時所(suo)需的合金元(yuan)素偏(pian)析均由(you)鋼凝固相(xiang)變(bian)所(suo)致。

  氮(dan)氣泡的(de)(de)形(xing)(xing)(xing)核和(he)長大(da)過程(cheng)(cheng)(cheng)復雜，且(qie)影(ying)響因(yin)(yin)素眾(zhong)多，包括凝(ning)固(gu)收縮、冶煉環境以及坩堝材質(zhi)等(deng)。因(yin)(yin)此(ci)，很難采用(yong)Pg值精確預測凝(ning)固(gu)過程(cheng)(cheng)(cheng)中(zhong)氮(dan)氣泡的(de)(de)形(xing)(xing)(xing)成(cheng)(cheng)(cheng)和(he)長大(da)。然而基于Yang等(deng)的(de)(de)實(shi)(shi)(shi)驗研究［70,77],在評估凝(ning)固(gu)壓力(li)、合金成(cheng)(cheng)(cheng)分等(deng)因(yin)(yin)素對氮(dan)氣泡形(xing)(xing)(xing)成(cheng)(cheng)(cheng)的(de)(de)影(ying)響程(cheng)(cheng)(cheng)度時，Pg起(qi)關(guan)鍵作(zuo)用(yong)。實(shi)(shi)(shi)際凝(ning)固(gu)過程(cheng)(cheng)(cheng)介(jie)于平(ping)衡(heng)凝(ning)固(gu)（固(gu)／液(ye)相中(zhong)溶質(zhi)完全(quan)(quan)擴(kuo)散）和(he)Scheil凝(ning)固(gu)（固(gu)相無溶質(zhi)擴(kuo)散，液(ye)相中(zhong)完全(quan)(quan)擴(kuo)散）之間70].因(yin)(yin)此(ci)，可(ke)分別計算平(ping)衡(heng)凝(ning)固(gu)和(he)Scheil凝(ning)固(gu)過程(cheng)(cheng)(cheng)中(zhong)的(de)(de)Aso、Ase和(he)Pg,闡明實(shi)(shi)(shi)際凝(ning)固(gu)過程(cheng)(cheng)(cheng)中(zhong)壓力(li)等(deng)因(yin)(yin)素對氮(dan)氣泡形(xing)(xing)(xing)成(cheng)(cheng)(cheng)的(de)(de)影(ying)響規律(lv)。

  現(xian)以21.5Cr5Mn1.5Ni0.25N含氮雙相(xiang)鋼D1鑄錠為例，對凝固(gu)過程中Aso、Ase和(he)P8的變化趨(qu)(qu)勢(shi)進(jin)行計算。圖2-61描述了(le)ΔAso(=Asa-Aso,0)和(he)AAse(=Ase-Ase,o)隨固(gu)相(xiang)質(zhi)量分(fen)數的變化趨(qu)(qu)勢(shi)（Aso,0和(he)Asc,0分(fen)別為D1鑄錠凝固(gu)時Aso和(he)Ase的初(chu)始值）。

  在(zai)平衡(heng)凝(ning)(ning)(ning)固(gu)和(he)(he)Scheil凝(ning)(ning)(ning)固(gu)過(guo)程(cheng)中(zhong)(zhong)，ΔAso的(de)(de)(de)最小(xiao)值(zhi)分(fen)別為－0.145和(he)(he)－0.397,與(yu)此相對(dui)應(ying)的(de)(de)(de)ΔAse值(zhi)最大(da)(da)，分(fen)別為0.68和(he)(he)0.92.在(zai)整個凝(ning)(ning)(ning)固(gu)過(guo)程(cheng)中(zhong)(zhong)，由(you)于(yu)ΔAse與(yu)ΔAso之(zhi)和(he)(he)始終大(da)(da)于(yu)零，因而枝(zhi)晶(jing)間殘余液(ye)相中(zhong)(zhong)氮(dan)(dan)偏析對(dui)D1 鑄(zhu)錠凝(ning)(ning)(ning)固(gu)過(guo)程(cheng)中(zhong)(zhong)氮(dan)(dan)氣(qi)泡(pao)形(xing)成(cheng)的(de)(de)(de)影(ying)響(xiang)大(da)(da)于(yu)氮(dan)(dan)溶解(jie)度(du)，起主導(dao)作(zuo)用(yong)。此外(wai)，在(zai)整個凝(ning)(ning)(ning)固(gu)過(guo)程(cheng)中(zhong)(zhong)，P8變(bian)化趨勢如圖(tu)2-62所示，其變(bian)化規律(lv)與(yu)Young等(deng)。的(de)(de)(de)研(yan)究結果一致，Pg的(de)(de)(de)最大(da)(da)值(zhi)Pg與(yu)Ase+Aso的(de)(de)(de)最大(da)(da)值(zhi)相對(dui)應(ying)，且在(zai)平衡(heng)凝(ning)(ning)(ning)固(gu)和(he)(he) Scheil 凝(ning)(ning)(ning)固(gu)過(guo)程(cheng)中(zhong)(zhong)分(fen)別為0.63MPa和(he)(he)0.62MPa.此外(wai)，可(ke)通過(guo)對(dui)比不同鑄(zhu)錠中(zhong)(zhong)的(de)(de)(de)探討凝(ning)(ning)(ning)固(gu)壓(ya)力、初始氮(dan)(dan)質量分(fen)數以及合金元素（鉻和(he)(he)錳）等(deng)對(dui)液(ye)相中(zhong)(zhong)氮(dan)(dan)氣(qi)泡(pao)形(xing)成(cheng)的(de)(de)(de)影(ying)響(xiang)，進而明(ming)晰各(ge)因素對(dui)氮(dan)(dan)氣(qi)孔形(xing)成(cheng)的(de)(de)(de)影(ying)響(xiang)規律(lv)。