固(gu)(gu)(gu)(gu)溶(rong)(rong)(rong)(rong)(rong)(rong)處(chu)理是(shi)將(jiang)合(he)(he)(he)金(jin)加(jia)熱(re)到(dao)高(gao)(gao)溫(wen)(wen)單-相(xiang)區恒(heng)溫(wen)(wen)保(bao)持,使過(guo)(guo)剩(sheng)相(xiang)溶(rong)(rong)(rong)(rong)(rong)(rong)解(jie)到(dao)溶(rong)(rong)(rong)(rong)(rong)(rong)體(ti)(ti)后快速冷(leng)(leng)卻、以(yi)(yi)得(de)到(dao)過(guo)(guo)飽(bao)和(he)固(gu)(gu)(gu)(gu)溶(rong)(rong)(rong)(rong)(rong)(rong)體(ti)(ti)的(de)(de)(de)(de)熱(re)處(chu)理工藝。首先,固(gu)(gu)(gu)(gu)溶(rong)(rong)(rong)(rong)(rong)(rong)處(chu)理是(shi)為(wei)(wei)(wei)了溶(rong)(rong)(rong)(rong)(rong)(rong)解(jie)基(ji)體(ti)(ti)內碳(tan)化(hua)物(wu)、γ'相(xiang)等以(yi)(yi)得(de)到(dao)均(jun)(jun)勻的(de)(de)(de)(de)過(guo)(guo)飽(bao)和(he)固(gu)(gu)(gu)(gu)溶(rong)(rong)(rong)(rong)(rong)(rong)體(ti)(ti),便(bian)于(yu)時(shi)效(xiao)時(shi)重新析(xi)(xi)(xi)出(chu)(chu)顆粒(li)細小、分(fen)布均(jun)(jun)勻的(de)(de)(de)(de)碳(tan)化(hua)物(wu)和(he)γ'等強化(hua)相(xiang),同時(shi)消除由(you)于(yu)冷(leng)(leng)熱(re)加(jia)工產生(sheng)的(de)(de)(de)(de)應力。使合(he)(he)(he)金(jin)發生(sheng)再結晶(jing)。其(qi)次(ci),固(gu)(gu)(gu)(gu)溶(rong)(rong)(rong)(rong)(rong)(rong)處(chu)理是(shi)為(wei)(wei)(wei)了獲得(de)適宜的(de)(de)(de)(de)晶(jing)粒(li)度(du),以(yi)(yi)保(bao)證(zheng)合(he)(he)(he)金(jin)高(gao)(gao)溫(wen)(wen)抗蠕(ru)變(bian)性(xing)能。固(gu)(gu)(gu)(gu)溶(rong)(rong)(rong)(rong)(rong)(rong)處(chu)理的(de)(de)(de)(de)溫(wen)(wen)度(du)范圍為(wei)(wei)(wei)980~1250℃,主要(yao)根據(ju)各個合(he)(he)(he)金(jin)中相(xiang)析(xi)(xi)(xi)出(chu)(chu)和(he)溶(rong)(rong)(rong)(rong)(rong)(rong)解(jie)規律及(ji)使用要(yao)求(qiu)來(lai)選擇,以(yi)(yi)保(bao)證(zheng)主要(yao)強化(hua)相(xiang)必要(yao)的(de)(de)(de)(de)析(xi)(xi)(xi)出(chu)(chu)條件(jian)和(he)一定的(de)(de)(de)(de)晶(jing)粒(li)度(du)。對(dui)于(yu)長(chang)期高(gao)(gao)溫(wen)(wen)使用的(de)(de)(de)(de)合(he)(he)(he)金(jin),要(yao)求(qiu)有較(jiao)(jiao)好(hao)的(de)(de)(de)(de)高(gao)(gao)溫(wen)(wen)持久和(he)蠕(ru)變(bian)性(xing)能,應選擇較(jiao)(jiao)高(gao)(gao)的(de)(de)(de)(de)固(gu)(gu)(gu)(gu)溶(rong)(rong)(rong)(rong)(rong)(rong)溫(wen)(wen)度(du)以(yi)(yi)獲得(de)較(jiao)(jiao)大的(de)(de)(de)(de)晶(jing)粒(li)度(du);對(dui)于(yu)中溫(wen)(wen)使用并要(yao)求(qiu)較(jiao)(jiao)好(hao)的(de)(de)(de)(de)室溫(wen)(wen)硬度(du)、屈服強度(du)、拉伸強度(du)、沖擊韌性(xing)和(he)疲勞強度(du)的(de)(de)(de)(de)合(he)(he)(he)金(jin),可采(cai)用較(jiao)(jiao)低(di)的(de)(de)(de)(de)固(gu)(gu)(gu)(gu)溶(rong)(rong)(rong)(rong)(rong)(rong)溫(wen)(wen)度(du),保(bao)證(zheng)較(jiao)(jiao)小的(de)(de)(de)(de)晶(jing)粒(li)度(du)。高(gao)(gao)溫(wen)(wen)固(gu)(gu)(gu)(gu)溶(rong)(rong)(rong)(rong)(rong)(rong)處(chu)理時(shi),各種(zhong)析(xi)(xi)(xi)出(chu)(chu)相(xiang)都(dou)逐步溶(rong)(rong)(rong)(rong)(rong)(rong)解(jie),同時(shi)晶(jing)粒(li)長(chang)大;低(di)溫(wen)(wen)固(gu)(gu)(gu)(gu)溶(rong)(rong)(rong)(rong)(rong)(rong)處(chu)理時(shi),不僅有主要(yao)強化(hua)相(xiang)的(de)(de)(de)(de)溶(rong)(rong)(rong)(rong)(rong)(rong)解(jie),而且可能有某些(xie)相(xiang)的(de)(de)(de)(de)析(xi)(xi)(xi)出(chu)(chu)。對(dui)于(yu)過(guo)(guo)飽(bao)和(he)度(du)低(di)的(de)(de)(de)(de)合(he)(he)(he)金(jin),通常選擇較(jiao)(jiao)快的(de)(de)(de)(de)冷(leng)(leng)卻速度(du);對(dui)于(yu)過(guo)(guo)飽(bao)和(he)度(du)高(gao)(gao)的(de)(de)(de)(de)合(he)(he)(he)金(jin),通常為(wei)(wei)(wei)空氣中冷(leng)(leng)卻。
對2205雙相(xiang)不銹鋼進行不同溫度的固溶處理會導致2205雙相不銹(xiu)鋼兩相組織的改變,進而導致其性能的差異,圖3.1是在不同溫度下2205雙相不銹鋼固溶處理后的微觀組織。
選取1000℃作為最(zui)低(di)固溶溫度(du),當熱處理(li)溫度(du)低(di)于950℃時(shi),雙相(xiang)不(bu)(bu)銹鋼基體(ti)(ti)(ti)會(hui)析出雜質相(xiang)σ相(xiang),σ相(xiang)作為富(fu)含Cr、Mo的硬脆相(xiang),其(qi)存(cun)在降(jiang)低(di)雙相(xiang)不(bu)(bu)銹鋼的耐(nai)蝕(shi)性能(neng)。圖(tu)3.1(a)為950℃的微觀組織(zhi),。相(xiang)廣泛分布于鐵素體(ti)(ti)(ti)/奧(ao)(ao)(ao)氏(shi)體(ti)(ti)(ti)晶(jing)(jing)界。當溫度(du)達到(dao)1000℃時(shi),σ相(xiang)會(hui)消(xiao)失,雙相(xiang)不(bu)(bu)銹鋼中只存(cun)在鐵素體(ti)(ti)(ti)相(xiang)和奧(ao)(ao)(ao)氏(shi)體(ti)(ti)(ti)相(xiang)。圖(tu)3.1(b)~(f)中深色區為鐵素體(ti)(ti)(ti),淺色區為奧(ao)(ao)(ao)氏(shi)體(ti)(ti)(ti)。奧(ao)(ao)(ao)氏(shi)體(ti)(ti)(ti)以(yi)鐵素體(ti)(ti)(ti)為基體(ti)(ti)(ti),呈帶(dai)狀(zhuang)或(huo)島狀(zhuang)分布于鐵素體(ti)(ti)(ti)上(shang)。隨著(zhu)溫度(du)的升高,奧(ao)(ao)(ao)氏(shi)體(ti)(ti)(ti)晶(jing)(jing)粒(li)尺寸變大(da)。
利用IAS圖像分析軟件(jian)測(ce)量(liang)并計(ji)算相(xiang)(xiang)比例(li),每個熱處(chu)理溫度(du)(du)(du)下的(de)金(jin)相(xiang)(xiang)圖取(qu)8張(zhang)計(ji)算,求取(qu)平均值。表3.2給出了利用IAS圖像分析軟件(jian)計(ji)算得(de)到不同固(gu)溶溫度(du)(du)(du)溫度(du)(du)(du)下2205雙相(xiang)(xiang)不銹鋼的(de)相(xiang)(xiang)比例(li)。1000℃時,鐵(tie)(tie)素(su)體含(han)(han)量(liang)為48.3%,隨(sui)著(zhu)固(gu)溶溫度(du)(du)(du)的(de)升(sheng)高,鐵(tie)(tie)素(su)體相(xiang)(xiang)含(han)(han)量(liang)增加,奧氏體相(xiang)(xiang)含(han)(han)量(liang)下降,直到1200℃時,鐵(tie)(tie)素(su)體含(han)(han)量(liang)達到62.3%,奧氏體含(han)(han)量(liang)僅占37.7%.這種鐵(tie)(tie)素(su)體與(yu)奧氏體隨(sui)固(gu)溶溫度(du)(du)(du)的(de)變(bian)(bian)化(hua)規律(lv)前人的(de)研究結(jie)果(guo)相(xiang)(xiang)一致。兩相(xiang)(xiang)比例(li)的(de)變(bian)(bian)化(hua)曲線如圖3.2所示,兩相(xiang)(xiang)與(yu)溫度(du)(du)(du)的(de)關系呈(cheng)線性變(bian)(bian)化(hua)。當固(gu)溶溫度(du)(du)(du)約為1040℃時,其相(xiang)(xiang)比例(li)為1:1。
因此在(zai)本(ben)實驗的6個固(gu)溶(rong)溫度中,當固(gu)溶(rong)溫度為1050℃時(shi),雙相(xiang)不(bu)銹(xiu)鋼相(xiang)比例最接近1:1。
采用顯微(wei)硬度(du)儀(yi)壓頭(tou)為菱形壓頭(tou),荷(he)載F為4.8N,分(fen)別測出(chu)菱形的兩個(ge)直(zhi)徑d1和d2,根據(ju)下(xia)式計算(suan)顯微(wei)硬度(du):
所(suo)(suo)有固溶(rong)溫(wen)度(du)試樣(yang)均測5個點(dian),最后求(qiu)取(qu)平均值為個固溶(rong)溫(wen)度(du)下2205雙相不(bu)銹鋼的(de)(de)顯微硬度(du)值。顯微硬度(du)值如(ru)表3.3所(suo)(suo)列,顯微硬度(du)隨固溶(rong)溫(wen)度(du)的(de)(de)變化曲(qu)線如(ru)圖3.3所(suo)(suo)示(shi)。
從圖3.3可知,2205雙相不銹鋼的顯微硬度先下降,后上升。這主要是由于當溫度為1000℃時,鐵素體相中間夾雜著小塊狀的二次奧氏體,當溫度達到1050℃后,二次奧氏體含量減少,組織均勻化程度提高,硬度減小。在此之后,隨著固溶溫度的增加,奧氏體含量減少,具有體心立方結構的奧氏體相屬于軟軔相,具有面心立方結構的鐵素體是強硬相,因此材料顯微硬度值又升高。同樣對2507雙相不(bu)銹鋼進行不同溫度的固溶處理會導致2507雙相不銹鋼兩相組織的改變,進而導致其性能的差異,以下是2507雙相不銹鋼在不同溫度下固溶處理后的微觀組織。
2507雙(shuang)相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)不銹鋼(gang)分(fen)別在1000℃、1050℃、1100℃、1150℃、1200℃下固(gu)(gu)(gu)溶(rong)(rong)0.5h后水冷的(de)(de)金相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)組織如圖(tu)(tu)(tu)3.4所(suo)(suo)示。從圖(tu)(tu)(tu)3.4可以清晰(xi)地得知當(dang)固(gu)(gu)(gu)溶(rong)(rong)溫(wen)度(du)(du)(du)為1000℃時鐵(tie)素(su)體相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)與(yu)奧氏體相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)兩相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)界(jie)處(chu)(chu)有σ相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)析(xi)出,隨固(gu)(gu)(gu)溶(rong)(rong)處(chu)(chu)理溫(wen)度(du)(du)(du)升高(gao)到(dao)1050℃時σ相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)已經(jing)溶(rong)(rong)解。利用Image-Pro-Plus 圖(tu)(tu)(tu)像分(fen)析(xi)儀軟件6.0版測定的(de)(de)相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)比例如圖(tu)(tu)(tu)3.5所(suo)(suo)示。從圖(tu)(tu)(tu)3.5能(neng)夠獲得固(gu)(gu)(gu)溶(rong)(rong)熱(re)(re)(re)處(chu)(chu)理溫(wen)度(du)(du)(du)的(de)(de)增高(gao)會導致σ析(xi)出相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)含量(liang)降(jiang)低(di),當(dang)固(gu)(gu)(gu)溶(rong)(rong)熱(re)(re)(re)處(chu)(chu)理溫(wen)度(du)(du)(du)大于1050℃時σ相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)已經(jing)完(wan)全溶(rong)(rong)解。這(zhe)是由于固(gu)(gu)(gu)溶(rong)(rong)熱(re)(re)(re)處(chu)(chu)理溫(wen)度(du)(du)(du)的(de)(de)升高(gao)使(shi)鋼(gang)中(zhong)鐵(tie)素(su)體α相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)量(liang)增多,導致σ相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)形成元素(su)Cr和Mo在鐵(tie)素(su)體相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)中(zhong)的(de)(de)濃度(du)(du)(du)降(jiang)低(di),進而導致當(dang)固(gu)(gu)(gu)溶(rong)(rong)熱(re)(re)(re)處(chu)(chu)理溫(wen)度(du)(du)(du)大于1050℃時σ相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)的(de)(de)形成受到(dao)抑制。考慮到(dao)σ相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)硬且脆,能(neng)夠大幅度(du)(du)(du)減(jian)弱材料(liao)的(de)(de)塑性(xing)與(yu)韌(ren)性(xing),并(bing)且σ相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)富Cr,很容易(yi)在其(qi)周圍產生(sheng)貧Cr區降(jiang)低(di)DSS2507的(de)(de)抗腐蝕(shi)性(xing)能(neng),所(suo)(suo)以σ相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)為DSS2507析(xi)出相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)中(zhong)危害最大的(de)(de)相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang),因(yin)此,在實際應用過程中(zhong)要想將2507雙(shuang)相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)不銹鋼(gang)中(zhong)的(de)(de)熱(re)(re)(re)軋態σ相(xiang)(xiang)(xiang)(xiang)(xiang)(xiang)完(wan)全消除所(suo)(suo)選用的(de)(de)固(gu)(gu)(gu)溶(rong)(rong)溫(wen)度(du)(du)(du)要不低(di)于1050℃。
圖3.4中(zhong)深(shen)色組(zu)(zu)織是(shi)(shi)鐵素(su)(su)(su)體(ti)(ti)(ti)(ti)α相(xiang)(xiang)(xiang)(xiang)、淺色組(zu)(zu)織是(shi)(shi)奧(ao)(ao)氏(shi)體(ti)(ti)(ti)(ti)γ相(xiang)(xiang)(xiang)(xiang)。從圖3.4可知奧(ao)(ao)氏(shi)體(ti)(ti)(ti)(ti)γ相(xiang)(xiang)(xiang)(xiang)首先(xian)表現為(wei)長條狀,隨(sui)著固(gu)溶(rong)(rong)處理(li)(li)溫(wen)(wen)度(du)(du)(du)的(de)(de)(de)升(sheng)高(gao)(gao)(gao)(gao)而逐(zhu)漸(jian)變(bian)(bian)短,變(bian)(bian)成島(dao)狀分布(bu)在(zai)基體(ti)(ti)(ti)(ti)鐵素(su)(su)(su)體(ti)(ti)(ti)(ti)上(shang)面(mian)。從圖3.5及表3.4中(zhong)給出(chu)的(de)(de)(de)相(xiang)(xiang)(xiang)(xiang)比(bi)例(li)測量(liang)結果能(neng)夠獲得鋼中(zhong)鐵素(su)(su)(su)體(ti)(ti)(ti)(ti)α相(xiang)(xiang)(xiang)(xiang)量(liang)隨(sui)固(gu)溶(rong)(rong)熱(re)處理(li)(li)溫(wen)(wen)度(du)(du)(du)的(de)(de)(de)升(sheng)高(gao)(gao)(gao)(gao)而上(shang)升(sheng),奧(ao)(ao)氏(shi)體(ti)(ti)(ti)(ti)γ相(xiang)(xiang)(xiang)(xiang)體(ti)(ti)(ti)(ti)積(ji)分數(shu)隨(sui)著固(gu)溶(rong)(rong)溫(wen)(wen)度(du)(du)(du)的(de)(de)(de)上(shang)升(sheng)而下(xia)降(jiang),這是(shi)(shi)由于在(zai)較(jiao)高(gao)(gao)(gao)(gao)的(de)(de)(de)固(gu)溶(rong)(rong)溫(wen)(wen)度(du)(du)(du)下(xia)2507雙相(xiang)(xiang)(xiang)(xiang)不銹(xiu)鋼呈現出(chu)的(de)(de)(de)組(zu)(zu)織為(wei)單(dan)一的(de)(de)(de)鐵素(su)(su)(su)體(ti)(ti)(ti)(ti),隨(sui)固(gu)溶(rong)(rong)熱(re)處理(li)(li)溫(wen)(wen)度(du)(du)(du)的(de)(de)(de)降(jiang)低(di)鐵素(su)(su)(su)體(ti)(ti)(ti)(ti)逐(zhu)步轉化為(wei)奧(ao)(ao)氏(shi)體(ti)(ti)(ti)(ti)組(zu)(zu)織,即固(gu)溶(rong)(rong)熱(re)處理(li)(li)溫(wen)(wen)度(du)(du)(du)的(de)(de)(de)升(sheng)高(gao)(gao)(gao)(gao)導致奧(ao)(ao)氏(shi)體(ti)(ti)(ti)(ti)逐(zhu)漸(jian)轉變(bian)(bian)為(wei)鐵素(su)(su)(su)體(ti)(ti)(ti)(ti)組(zu)(zu)織。從圖3.5可以看出(chu)當固(gu)溶(rong)(rong)熱(re)處理(li)(li)溫(wen)(wen)度(du)(du)(du)在(zai)1000~1050℃之間時奧(ao)(ao)氏(shi)體(ti)(ti)(ti)(ti)y相(xiang)(xiang)(xiang)(xiang)比(bi)例(li)減小的(de)(de)(de)比(bi)較(jiao)緩慢,隨(sui)固(gu)溶(rong)(rong)熱(re)處理(li)(li)溫(wen)(wen)度(du)(du)(du)的(de)(de)(de)升(sheng)高(gao)(gao)(gao)(gao)奧(ao)(ao)氏(shi)體(ti)(ti)(ti)(ti)γ相(xiang)(xiang)(xiang)(xiang)含量(liang)減少(shao)的(de)(de)(de)趨勢加快,這是(shi)(shi)因為(wei)2507雙相(xiang)(xiang)(xiang)(xiang)不銹(xiu)鋼中(zhong)的(de)(de)(de)氮元素(su)(su)(su)是(shi)(shi)奧(ao)(ao)氏(shi)體(ti)(ti)(ti)(ti)形成元素(su)(su)(su),在(zai)較(jiao)低(di)固(gu)溶(rong)(rong)溫(wen)(wen)度(du)(du)(du)下(xia)抑制了奧(ao)(ao)氏(shi)體(ti)(ti)(ti)(ti)相(xiang)(xiang)(xiang)(xiang)向鐵素(su)(su)(su)體(ti)(ti)(ti)(ti)相(xiang)(xiang)(xiang)(xiang)的(de)(de)(de)轉變(bian)(bian),而固(gu)溶(rong)(rong)熱(re)處理(li)(li)溫(wen)(wen)度(du)(du)(du)的(de)(de)(de)升(sheng)高(gao)(gao)(gao)(gao)會(hui)使N元素(su)(su)(su)穩(wen)定奧(ao)(ao)氏(shi)體(ti)(ti)(ti)(ti)相(xiang)(xiang)(xiang)(xiang)的(de)(de)(de)作用逐(zhu)漸(jian)減弱,進而導致奧(ao)(ao)氏(shi)體(ti)(ti)(ti)(ti)γ相(xiang)(xiang)(xiang)(xiang)向鐵素(su)(su)(su)體(ti)(ti)(ti)(ti)α相(xiang)(xiang)(xiang)(xiang)轉變(bian)(bian)速度(du)(du)(du)加快。
2507雙(shuang)(shuang)相(xiang)(xiang)(xiang)(xiang)(xiang)不銹鋼(gang)中的(de)(de)(de)奧(ao)(ao)氏(shi)(shi)體(ti)相(xiang)(xiang)(xiang)(xiang)(xiang)和鐵素(su)體(ti)相(xiang)(xiang)(xiang)(xiang)(xiang)這兩(liang)種(zhong)相(xiang)(xiang)(xiang)(xiang)(xiang)的(de)(de)(de)相(xiang)(xiang)(xiang)(xiang)(xiang)比(bi)例(li)主要受固(gu)溶(rong)(rong)(rong)處理(li)(li)(li)工藝以(yi)及自身化學成(cheng)分的(de)(de)(de)影響,當鋼(gang)的(de)(de)(de)主要化學成(cheng)分確定時(shi),則兩(liang)相(xiang)(xiang)(xiang)(xiang)(xiang)比(bi)例(li)與固(gu)溶(rong)(rong)(rong)處理(li)(li)(li)制度有(you)著密切(qie)聯系(xi)。DSS2507的(de)(de)(de)相(xiang)(xiang)(xiang)(xiang)(xiang)比(bi)例(li)又(you)影響著其自身的(de)(de)(de)性(xing)能(neng)(neng),其塑性(xing)隨著鐵素(su)體(ti)含(han)量的(de)(de)(de)增多而(er)(er)減弱(ruo)、耐應(ying)力(li)(li)腐(fu)蝕破裂能(neng)(neng)力(li)(li)隨著奧(ao)(ao)氏(shi)(shi)體(ti)含(han)量升高(gao)而(er)(er)減弱(ruo),進而(er)(er)認為(wei)當鐵素(su)體(ti)α相(xiang)(xiang)(xiang)(xiang)(xiang)跟(gen)奧(ao)(ao)氏(shi)(shi)體(ti)γ相(xiang)(xiang)(xiang)(xiang)(xiang)這兩(liang)相(xiang)(xiang)(xiang)(xiang)(xiang)相(xiang)(xiang)(xiang)(xiang)(xiang)比(bi)例(li)接近1:1時(shi)雙(shuang)(shuang)相(xiang)(xiang)(xiang)(xiang)(xiang)不銹鋼(gang)的(de)(de)(de)綜(zong)合性(xing)能(neng)(neng)最佳(jia),有(you)較好(hao)的(de)(de)(de)抗腐(fu)蝕能(neng)(neng)力(li)(li)以(yi)及較優的(de)(de)(de)力(li)(li)學性(xing)能(neng)(neng)。從(cong)圖3.5可(ke)(ke)知固(gu)溶(rong)(rong)(rong)熱處理(li)(li)(li)溫度在1050~1100℃之間(jian)時(shi)可(ke)(ke)以(yi)使鋼(gang)中的(de)(de)(de)兩(liang)相(xiang)(xiang)(xiang)(xiang)(xiang)組織比(bi)例(li)達到(dao)(dao)1:1,本實驗中所選(xuan)(xuan)用的(de)(de)(de)5種(zhong)固(gu)溶(rong)(rong)(rong)溫度中1050℃時(shi)鐵素(su)體(ti)α相(xiang)(xiang)(xiang)(xiang)(xiang)跟(gen)奧(ao)(ao)氏(shi)(shi)體(ti)γ相(xiang)(xiang)(xiang)(xiang)(xiang)比(bi)例(li)最接近1:1,進而(er)(er)可(ke)(ke)以(yi)認為(wei)選(xuan)(xuan)擇較優的(de)(de)(de)固(gu)溶(rong)(rong)(rong)熱處理(li)(li)(li)溫度使DSS2507中的(de)(de)(de)兩(liang)相(xiang)(xiang)(xiang)(xiang)(xiang)含(han)量比(bi)例(li)達到(dao)(dao)1:1是有(you)可(ke)(ke)能(neng)(neng)的(de)(de)(de),在實際應(ying)用過(guo)程中為(wei)了使2507雙(shuang)(shuang)相(xiang)(xiang)(xiang)(xiang)(xiang)不銹鋼(gang)獲得較好(hao)的(de)(de)(de)綜(zong)合性(xing)能(neng)(neng),進行固(gu)溶(rong)(rong)(rong)處理(li)(li)(li)時(shi)選(xuan)(xuan)取的(de)(de)(de)固(gu)溶(rong)(rong)(rong)溫度應(ying)該(gai)在1050~1100℃之間(jian)。
2507雙(shuang)(shuang)相不銹鋼(gang)分別在(zai)1000℃、1050℃、1100℃、1150℃、1200℃固(gu)溶(rong)(rong)0.5h后水冷的(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)(ying)(ying)(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)值(zhi)如圖3.6所示。從(cong)圖3.6可知DSS2507的(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)(ying)(ying)(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)隨(sui)(sui)(sui)固(gu)溶(rong)(rong)處(chu)(chu)(chu)(chu)理(li)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)(de)升(sheng)(sheng)高先(xian)減小后變(bian)(bian)大呈曲(qu)線(xian)變(bian)(bian)化。在(zai)1000~1050℃溫(wen)(wen)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)范圍內鋼(gang)的(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)(ying)(ying)(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)隨(sui)(sui)(sui)固(gu)溶(rong)(rong)熱處(chu)(chu)(chu)(chu)理(li)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)(de)增高而逐漸(jian)(jian)減小,1050~1200℃范圍內隨(sui)(sui)(sui)固(gu)溶(rong)(rong)熱處(chu)(chu)(chu)(chu)理(li)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)(de)上升(sheng)(sheng)硬(ying)(ying)(ying)(ying)(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)又(you)漸(jian)(jian)漸(jian)(jian)變(bian)(bian)大,且(qie)1050℃時(shi)DSS2507的(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)(ying)(ying)(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)表現為最小。從(cong)3.2.1節分析可知當固(gu)溶(rong)(rong)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)為1000℃時(shi)在(zai)鐵(tie)素(su)體(ti)和奧氏(shi)體(ti)相界處(chu)(chu)(chu)(chu)有σ相析出,σ相是一種硬(ying)(ying)(ying)(ying)(ying)(ying)而脆的(de)(de)(de)(de)(de)(de)(de)相,能夠提高雙(shuang)(shuang)相不銹鋼(gang)的(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)(ying)(ying)(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)值(zhi),所以1000℃下(xia)鋼(gang)有較高的(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)(ying)(ying)(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du),而σ相會(hui)隨(sui)(sui)(sui)固(gu)溶(rong)(rong)熱處(chu)(chu)(chu)(chu)理(li)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)(de)升(sheng)(sheng)高而漸(jian)(jian)漸(jian)(jian)溶(rong)(rong)解到基體(ti)中,DSS2507的(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)(ying)(ying)(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)有下(xia)降(jiang)的(de)(de)(de)(de)(de)(de)(de)趨勢(shi)(shi);同時(shi)又(you)由于固(gu)溶(rong)(rong)熱處(chu)(chu)(chu)(chu)理(li)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)(de)增高導(dao)致鋼(gang)中的(de)(de)(de)(de)(de)(de)(de)鐵(tie)素(su)體(ti)相量增加(jia)而奧氏(shi)體(ti)相量降(jiang)低(di),在(zai)室溫(wen)(wen)下(xia)鐵(tie)素(su)體(ti)是體(ti)心(xin)立方結構(bcc)奧氏(shi)體(ti)是面(mian)心(xin)立方結構(fcc),前(qian)者(zhe)硬(ying)(ying)(ying)(ying)(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)要(yao)高于后者(zhe),因(yin)此在(zai)鐵(tie)素(su)體(ti)含量逐漸(jian)(jian)升(sheng)(sheng)高的(de)(de)(de)(de)(de)(de)(de)情況下(xia)鋼(gang)的(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)(ying)(ying)(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)也(ye)逐漸(jian)(jian)升(sheng)(sheng)高,即(ji)隨(sui)(sui)(sui)著固(gu)溶(rong)(rong)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)(de)升(sheng)(sheng)高2507 雙(shuang)(shuang)相不銹鋼(gang)的(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)(ying)(ying)(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)呈升(sheng)(sheng)高的(de)(de)(de)(de)(de)(de)(de)趨勢(shi)(shi)。綜上所述,隨(sui)(sui)(sui)固(gu)溶(rong)(rong)溫(wen)(wen)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)從(cong)1000℃上升(sheng)(sheng)到1200℃,2507雙(shuang)(shuang)相不銹鋼(gang)硬(ying)(ying)(ying)(ying)(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)(du)(du)(du)呈先(xian)降(jiang)低(di)后升(sheng)(sheng)高的(de)(de)(de)(de)(de)(de)(de)變(bian)(bian)化趨勢(shi)(shi)。