固(gu)溶(rong)(rong)(rong)處(chu)(chu)(chu)(chu)理是(shi)(shi)(shi)將合(he)金加熱到(dao)高(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)單－相(xiang)(xiang)(xiang)(xiang)區恒溫(wen)(wen)(wen)(wen)(wen)(wen)保持，使(shi)過剩相(xiang)(xiang)(xiang)(xiang)溶(rong)(rong)(rong)解(jie)到(dao)溶(rong)(rong)(rong)體后(hou)快(kuai)速冷(leng)(leng)卻、以(yi)得(de)(de)到(dao)過飽和(he)固(gu)溶(rong)(rong)(rong)體的(de)熱處(chu)(chu)(chu)(chu)理工(gong)藝。首先，固(gu)溶(rong)(rong)(rong)處(chu)(chu)(chu)(chu)理是(shi)(shi)(shi)為(wei)了溶(rong)(rong)(rong)解(jie)基體內碳化(hua)物、γ'相(xiang)(xiang)(xiang)(xiang)等(deng)(deng)以(yi)得(de)(de)到(dao)均勻的(de)過飽和(he)固(gu)溶(rong)(rong)(rong)體，便于(yu)時效時重新析(xi)出(chu)顆(ke)粒(li)細小(xiao)、分布均勻的(de)碳化(hua)物和(he)γ'等(deng)(deng)強(qiang)化(hua)相(xiang)(xiang)(xiang)(xiang)，同時消(xiao)除由于(yu)冷(leng)(leng)熱加工(gong)產生(sheng)的(de)應(ying)力。使(shi)合(he)金發生(sheng)再結晶。其次(ci)，固(gu)溶(rong)(rong)(rong)處(chu)(chu)(chu)(chu)理是(shi)(shi)(shi)為(wei)了獲得(de)(de)適宜的(de)晶粒(li)度(du)(du)(du)(du)，以(yi)保證(zheng)合(he)金高(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)抗蠕(ru)(ru)變性能。固(gu)溶(rong)(rong)(rong)處(chu)(chu)(chu)(chu)理的(de)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)范圍為(wei)980~1250℃,主(zhu)要(yao)根據各個合(he)金中相(xiang)(xiang)(xiang)(xiang)析(xi)出(chu)和(he)溶(rong)(rong)(rong)解(jie)規律及使(shi)用(yong)(yong)要(yao)求來選(xuan)(xuan)擇，以(yi)保證(zheng)主(zhu)要(yao)強(qiang)化(hua)相(xiang)(xiang)(xiang)(xiang)必要(yao)的(de)析(xi)出(chu)條件(jian)和(he)一定的(de)晶粒(li)度(du)(du)(du)(du)。對(dui)于(yu)長(chang)期高(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)使(shi)用(yong)(yong)的(de)合(he)金，要(yao)求有較(jiao)好的(de)高(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)持久和(he)蠕(ru)(ru)變性能，應(ying)選(xuan)(xuan)擇較(jiao)高(gao)的(de)固(gu)溶(rong)(rong)(rong)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)以(yi)獲得(de)(de)較(jiao)大的(de)晶粒(li)度(du)(du)(du)(du)；對(dui)于(yu)中溫(wen)(wen)(wen)(wen)(wen)(wen)使(shi)用(yong)(yong)并要(yao)求較(jiao)好的(de)室溫(wen)(wen)(wen)(wen)(wen)(wen)硬度(du)(du)(du)(du)、屈(qu)服強(qiang)度(du)(du)(du)(du)、拉伸(shen)強(qiang)度(du)(du)(du)(du)、沖(chong)擊韌性和(he)疲(pi)勞(lao)強(qiang)度(du)(du)(du)(du)的(de)合(he)金，可采用(yong)(yong)較(jiao)低的(de)固(gu)溶(rong)(rong)(rong)溫(wen)(wen)(wen)(wen)(wen)(wen)度(du)(du)(du)(du)，保證(zheng)較(jiao)小(xiao)的(de)晶粒(li)度(du)(du)(du)(du)。高(gao)溫(wen)(wen)(wen)(wen)(wen)(wen)固(gu)溶(rong)(rong)(rong)處(chu)(chu)(chu)(chu)理時，各種析(xi)出(chu)相(xiang)(xiang)(xiang)(xiang)都逐步溶(rong)(rong)(rong)解(jie)，同時晶粒(li)長(chang)大；低溫(wen)(wen)(wen)(wen)(wen)(wen)固(gu)溶(rong)(rong)(rong)處(chu)(chu)(chu)(chu)理時，不僅有主(zhu)要(yao)強(qiang)化(hua)相(xiang)(xiang)(xiang)(xiang)的(de)溶(rong)(rong)(rong)解(jie)，而且可能有某些(xie)相(xiang)(xiang)(xiang)(xiang)的(de)析(xi)出(chu)。對(dui)于(yu)過飽和(he)度(du)(du)(du)(du)低的(de)合(he)金，通常(chang)(chang)選(xuan)(xuan)擇較(jiao)快(kuai)的(de)冷(leng)(leng)卻速度(du)(du)(du)(du)；對(dui)于(yu)過飽和(he)度(du)(du)(du)(du)高(gao)的(de)合(he)金，通常(chang)(chang)為(wei)空氣中冷(leng)(leng)卻。
對2205雙相不銹(xiu)鋼進行不同溫度的固溶處理會導致2205雙相(xiang)不銹鋼兩相組織的改變，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(zuo)為(wei)最低(di)固溶溫度(du)，當(dang)熱處理溫度(du)低(di)于950℃時(shi)，雙相(xiang)(xiang)(xiang)不銹(xiu)鋼基體(ti)(ti)(ti)(ti)會析(xi)出雜質相(xiang)(xiang)(xiang)σ相(xiang)(xiang)(xiang)，σ相(xiang)(xiang)(xiang)作(zuo)為(wei)富含Cr、Mo的(de)硬脆相(xiang)(xiang)(xiang)，其(qi)存在降(jiang)低(di)雙相(xiang)(xiang)(xiang)不銹(xiu)鋼的(de)耐蝕(shi)性能。圖3.1(a)為(wei)950℃的(de)微(wei)觀組織，。相(xiang)(xiang)(xiang)廣(guang)泛(fan)分布于鐵素(su)(su)體(ti)(ti)(ti)(ti)／奧氏(shi)體(ti)(ti)(ti)(ti)晶界。當(dang)溫度(du)達到1000℃時(shi)，σ相(xiang)(xiang)(xiang)會消(xiao)失，雙相(xiang)(xiang)(xiang)不銹(xiu)鋼中只存在鐵素(su)(su)體(ti)(ti)(ti)(ti)相(xiang)(xiang)(xiang)和奧氏(shi)體(ti)(ti)(ti)(ti)相(xiang)(xiang)(xiang)。圖3.1(b)~(f)中深色區(qu)為(wei)鐵素(su)(su)體(ti)(ti)(ti)(ti)，淺色區(qu)為(wei)奧氏(shi)體(ti)(ti)(ti)(ti)。奧氏(shi)體(ti)(ti)(ti)(ti)以(yi)鐵素(su)(su)體(ti)(ti)(ti)(ti)為(wei)基體(ti)(ti)(ti)(ti)，呈帶狀或島狀分布于鐵素(su)(su)體(ti)(ti)(ti)(ti)上(shang)。隨著溫度(du)的(de)升高，奧氏(shi)體(ti)(ti)(ti)(ti)晶粒尺(chi)寸變(bian)大。
利用(yong)IAS圖像(xiang)分析軟(ruan)件(jian)測量(liang)(liang)并計算相(xiang)比例(li)(li)，每個(ge)熱處理溫(wen)(wen)(wen)度(du)(du)下的(de)(de)金相(xiang)圖取8張計算，求取平均值。表3.2給出了利用(yong)IAS圖像(xiang)分析軟(ruan)件(jian)計算得(de)到(dao)不同固(gu)溶(rong)溫(wen)(wen)(wen)度(du)(du)溫(wen)(wen)(wen)度(du)(du)下2205雙相(xiang)不銹鋼的(de)(de)相(xiang)比例(li)(li)。1000℃時，鐵素體(ti)(ti)含(han)(han)(han)量(liang)(liang)為48.3%,隨著固(gu)溶(rong)溫(wen)(wen)(wen)度(du)(du)的(de)(de)升高(gao)，鐵素體(ti)(ti)相(xiang)含(han)(han)(han)量(liang)(liang)增(zeng)加，奧(ao)氏體(ti)(ti)相(xiang)含(han)(han)(han)量(liang)(liang)下降(jiang)，直到(dao)1200℃時，鐵素體(ti)(ti)含(han)(han)(han)量(liang)(liang)達到(dao)62.3%,奧(ao)氏體(ti)(ti)含(han)(han)(han)量(liang)(liang)僅占37.7%.這種鐵素體(ti)(ti)與奧(ao)氏體(ti)(ti)隨固(gu)溶(rong)溫(wen)(wen)(wen)度(du)(du)的(de)(de)變(bian)(bian)化規(gui)律前人(ren)的(de)(de)研究結(jie)果相(xiang)一(yi)致。兩相(xiang)比例(li)(li)的(de)(de)變(bian)(bian)化曲線如圖3.2所(suo)示，兩相(xiang)與溫(wen)(wen)(wen)度(du)(du)的(de)(de)關系呈線性變(bian)(bian)化。當(dang)固(gu)溶(rong)溫(wen)(wen)(wen)度(du)(du)約為1040℃時，其相(xiang)比例(li)(li)為1:1。
因此(ci)在(zai)本實驗的6個固溶(rong)溫度中，當固溶(rong)溫度為1050℃時(shi)，雙相(xiang)不銹鋼相(xiang)比例最接近1:1。
采用顯微硬度儀壓頭為(wei)菱(ling)形(xing)壓頭，荷載F為(wei)4.8N,分(fen)別測出菱(ling)形(xing)的(de)兩個直徑d1和d2,根據下式計算顯微硬度：
所有(you)固(gu)(gu)溶溫度(du)(du)試樣均測(ce)5個點，最后求取(qu)平均值為(wei)個固(gu)(gu)溶溫度(du)(du)下2205雙相(xiang)不銹(xiu)鋼(gang)的顯(xian)微硬(ying)(ying)度(du)(du)值。顯(xian)微硬(ying)(ying)度(du)(du)值如表3.3所列，顯(xian)微硬(ying)(ying)度(du)(du)隨(sui)固(gu)(gu)溶溫度(du)(du)的變化曲線如圖3.3所示。
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(xiang)不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雙相(xiang)(xiang)(xiang)(xiang)(xiang)不銹鋼(gang)分別在(zai)1000℃、1050℃、1100℃、1150℃、1200℃下固(gu)溶(rong)(rong)(rong)(rong)(rong)0.5h后水冷的金(jin)相(xiang)(xiang)(xiang)(xiang)(xiang)組織如圖(tu)3.4所(suo)示。從(cong)圖(tu)3.4可以清(qing)晰地得知當(dang)固(gu)溶(rong)(rong)(rong)(rong)(rong)溫(wen)度(du)為(wei)(wei)1000℃時(shi)鐵素體相(xiang)(xiang)(xiang)(xiang)(xiang)與(yu)奧氏體相(xiang)(xiang)(xiang)(xiang)(xiang)兩相(xiang)(xiang)(xiang)(xiang)(xiang)相(xiang)(xiang)(xiang)(xiang)(xiang)界處(chu)(chu)有σ相(xiang)(xiang)(xiang)(xiang)(xiang)析(xi)(xi)出，隨固(gu)溶(rong)(rong)(rong)(rong)(rong)處(chu)(chu)理溫(wen)度(du)升高(gao)(gao)到(dao)(dao)(dao)1050℃時(shi)σ相(xiang)(xiang)(xiang)(xiang)(xiang)已(yi)(yi)經溶(rong)(rong)(rong)(rong)(rong)解。利(li)用Image-Pro-Plus 圖(tu)像分析(xi)(xi)儀軟(ruan)件6.0版測(ce)定(ding)的相(xiang)(xiang)(xiang)(xiang)(xiang)比例如圖(tu)3.5所(suo)示。從(cong)圖(tu)3.5能(neng)夠(gou)獲得固(gu)溶(rong)(rong)(rong)(rong)(rong)熱(re)處(chu)(chu)理溫(wen)度(du)的增高(gao)(gao)會(hui)導(dao)致σ析(xi)(xi)出相(xiang)(xiang)(xiang)(xiang)(xiang)含量降低(di)(di)，當(dang)固(gu)溶(rong)(rong)(rong)(rong)(rong)熱(re)處(chu)(chu)理溫(wen)度(du)大于(yu)1050℃時(shi)σ相(xiang)(xiang)(xiang)(xiang)(xiang)已(yi)(yi)經完(wan)全溶(rong)(rong)(rong)(rong)(rong)解。這是由于(yu)固(gu)溶(rong)(rong)(rong)(rong)(rong)熱(re)處(chu)(chu)理溫(wen)度(du)的升高(gao)(gao)使鋼(gang)中(zhong)鐵素體α相(xiang)(xiang)(xiang)(xiang)(xiang)量增多，導(dao)致σ相(xiang)(xiang)(xiang)(xiang)(xiang)形成元素Cr和(he)Mo在(zai)鐵素體相(xiang)(xiang)(xiang)(xiang)(xiang)中(zhong)的濃度(du)降低(di)(di)，進而(er)導(dao)致當(dang)固(gu)溶(rong)(rong)(rong)(rong)(rong)熱(re)處(chu)(chu)理溫(wen)度(du)大于(yu)1050℃時(shi)σ相(xiang)(xiang)(xiang)(xiang)(xiang)的形成受到(dao)(dao)(dao)抑制。考慮(lv)到(dao)(dao)(dao)σ相(xiang)(xiang)(xiang)(xiang)(xiang)硬且脆，能(neng)夠(gou)大幅度(du)減弱材料的塑性(xing)與(yu)韌性(xing)，并且σ相(xiang)(xiang)(xiang)(xiang)(xiang)富Cr,很容易在(zai)其周圍產生(sheng)貧Cr區降低(di)(di)DSS2507的抗腐蝕性(xing)能(neng)，所(suo)以σ相(xiang)(xiang)(xiang)(xiang)(xiang)為(wei)(wei)DSS2507析(xi)(xi)出相(xiang)(xiang)(xiang)(xiang)(xiang)中(zhong)危害最大的相(xiang)(xiang)(xiang)(xiang)(xiang)，因此，在(zai)實際應用過程中(zhong)要想將2507雙相(xiang)(xiang)(xiang)(xiang)(xiang)不銹鋼(gang)中(zhong)的熱(re)軋(ya)態σ相(xiang)(xiang)(xiang)(xiang)(xiang)完(wan)全消除所(suo)選(xuan)用的固(gu)溶(rong)(rong)(rong)(rong)(rong)溫(wen)度(du)要不低(di)(di)于(yu)1050℃。
圖(tu)3.4中深(shen)色(se)組織是(shi)鐵(tie)素(su)體(ti)(ti)α相(xiang)(xiang)(xiang)(xiang)(xiang)、淺色(se)組織是(shi)奧(ao)(ao)(ao)(ao)氏(shi)體(ti)(ti)γ相(xiang)(xiang)(xiang)(xiang)(xiang)。從圖(tu)3.4可知奧(ao)(ao)(ao)(ao)氏(shi)體(ti)(ti)γ相(xiang)(xiang)(xiang)(xiang)(xiang)首先表現為(wei)(wei)長(chang)條狀，隨(sui)(sui)著固(gu)溶(rong)(rong)處理(li)溫(wen)(wen)度(du)的(de)(de)(de)升(sheng)(sheng)高(gao)而(er)逐漸(jian)變(bian)(bian)短，變(bian)(bian)成島狀分(fen)布在(zai)基體(ti)(ti)鐵(tie)素(su)體(ti)(ti)上(shang)面。從圖(tu)3.5及(ji)表3.4中給出(chu)的(de)(de)(de)相(xiang)(xiang)(xiang)(xiang)(xiang)比例測量結(jie)果能夠獲得鋼中鐵(tie)素(su)體(ti)(ti)α相(xiang)(xiang)(xiang)(xiang)(xiang)量隨(sui)(sui)固(gu)溶(rong)(rong)熱處理(li)溫(wen)(wen)度(du)的(de)(de)(de)升(sheng)(sheng)高(gao)而(er)上(shang)升(sheng)(sheng)，奧(ao)(ao)(ao)(ao)氏(shi)體(ti)(ti)γ相(xiang)(xiang)(xiang)(xiang)(xiang)體(ti)(ti)積分(fen)數(shu)隨(sui)(sui)著固(gu)溶(rong)(rong)溫(wen)(wen)度(du)的(de)(de)(de)上(shang)升(sheng)(sheng)而(er)下降，這(zhe)是(shi)由于在(zai)較高(gao)的(de)(de)(de)固(gu)溶(rong)(rong)溫(wen)(wen)度(du)下2507雙相(xiang)(xiang)(xiang)(xiang)(xiang)不(bu)銹(xiu)(xiu)鋼呈現出(chu)的(de)(de)(de)組織為(wei)(wei)單(dan)一的(de)(de)(de)鐵(tie)素(su)體(ti)(ti)，隨(sui)(sui)固(gu)溶(rong)(rong)熱處理(li)溫(wen)(wen)度(du)的(de)(de)(de)降低鐵(tie)素(su)體(ti)(ti)逐步轉化為(wei)(wei)奧(ao)(ao)(ao)(ao)氏(shi)體(ti)(ti)組織，即固(gu)溶(rong)(rong)熱處理(li)溫(wen)(wen)度(du)的(de)(de)(de)升(sheng)(sheng)高(gao)導致奧(ao)(ao)(ao)(ao)氏(shi)體(ti)(ti)逐漸(jian)轉變(bian)(bian)為(wei)(wei)鐵(tie)素(su)體(ti)(ti)組織。從圖(tu)3.5可以看出(chu)當固(gu)溶(rong)(rong)熱處理(li)溫(wen)(wen)度(du)在(zai)1000~1050℃之間(jian)時奧(ao)(ao)(ao)(ao)氏(shi)體(ti)(ti)y相(xiang)(xiang)(xiang)(xiang)(xiang)比例減小的(de)(de)(de)比較緩慢，隨(sui)(sui)固(gu)溶(rong)(rong)熱處理(li)溫(wen)(wen)度(du)的(de)(de)(de)升(sheng)(sheng)高(gao)奧(ao)(ao)(ao)(ao)氏(shi)體(ti)(ti)γ相(xiang)(xiang)(xiang)(xiang)(xiang)含(han)量減少的(de)(de)(de)趨勢加快(kuai)(kuai)，這(zhe)是(shi)因(yin)為(wei)(wei)2507雙相(xiang)(xiang)(xiang)(xiang)(xiang)不(bu)銹(xiu)(xiu)鋼中的(de)(de)(de)氮(dan)元(yuan)(yuan)素(su)是(shi)奧(ao)(ao)(ao)(ao)氏(shi)體(ti)(ti)形成元(yuan)(yuan)素(su)，在(zai)較低固(gu)溶(rong)(rong)溫(wen)(wen)度(du)下抑制了奧(ao)(ao)(ao)(ao)氏(shi)體(ti)(ti)相(xiang)(xiang)(xiang)(xiang)(xiang)向鐵(tie)素(su)體(ti)(ti)相(xiang)(xiang)(xiang)(xiang)(xiang)的(de)(de)(de)轉變(bian)(bian)，而(er)固(gu)溶(rong)(rong)熱處理(li)溫(wen)(wen)度(du)的(de)(de)(de)升(sheng)(sheng)高(gao)會(hui)使N元(yuan)(yuan)素(su)穩(wen)定奧(ao)(ao)(ao)(ao)氏(shi)體(ti)(ti)相(xiang)(xiang)(xiang)(xiang)(xiang)的(de)(de)(de)作用逐漸(jian)減弱，進而(er)導致奧(ao)(ao)(ao)(ao)氏(shi)體(ti)(ti)γ相(xiang)(xiang)(xiang)(xiang)(xiang)向鐵(tie)素(su)體(ti)(ti)α相(xiang)(xiang)(xiang)(xiang)(xiang)轉變(bian)(bian)速度(du)加快(kuai)(kuai)。
2507雙相(xiang)不(bu)銹鋼中(zhong)的(de)(de)奧(ao)氏體相(xiang)和鐵(tie)素(su)體相(xiang)這兩種相(xiang)的(de)(de)相(xiang)比(bi)例(li)(li)主(zhu)要(yao)受固(gu)(gu)溶(rong)(rong)(rong)處(chu)理工藝(yi)以及自身化學成分的(de)(de)影響，當鋼的(de)(de)主(zhu)要(yao)化學成分確定時(shi)，則兩相(xiang)比(bi)例(li)(li)與固(gu)(gu)溶(rong)(rong)(rong)處(chu)理制度有(you)著密切聯系。DSS2507的(de)(de)相(xiang)比(bi)例(li)(li)又(you)影響著其(qi)自身的(de)(de)性能(neng)，其(qi)塑性隨著鐵(tie)素(su)體含(han)量的(de)(de)增多而(er)減(jian)弱、耐應(ying)(ying)力腐蝕(shi)破裂能(neng)力隨著奧(ao)氏體含(han)量升(sheng)高而(er)減(jian)弱，進而(er)認(ren)為當鐵(tie)素(su)體α相(xiang)跟(gen)(gen)奧(ao)氏體γ相(xiang)這兩相(xiang)相(xiang)比(bi)例(li)(li)接近(jin)1:1時(shi)雙相(xiang)不(bu)銹鋼的(de)(de)綜合(he)性能(neng)最佳，有(you)較好的(de)(de)抗腐蝕(shi)能(neng)力以及較優的(de)(de)力學性能(neng)。從圖3.5可知(zhi)固(gu)(gu)溶(rong)(rong)(rong)熱(re)處(chu)理溫度在1050~1100℃之間(jian)時(shi)可以使(shi)(shi)鋼中(zhong)的(de)(de)兩相(xiang)組織比(bi)例(li)(li)達(da)到(dao)1:1,本(ben)實(shi)驗中(zhong)所選用的(de)(de)5種固(gu)(gu)溶(rong)(rong)(rong)溫度中(zhong)1050℃時(shi)鐵(tie)素(su)體α相(xiang)跟(gen)(gen)奧(ao)氏體γ相(xiang)比(bi)例(li)(li)最接近(jin)1:1,進而(er)可以認(ren)為選擇較優的(de)(de)固(gu)(gu)溶(rong)(rong)(rong)熱(re)處(chu)理溫度使(shi)(shi)DSS2507中(zhong)的(de)(de)兩相(xiang)含(han)量比(bi)例(li)(li)達(da)到(dao)1:1是(shi)有(you)可能(neng)的(de)(de)，在實(shi)際(ji)應(ying)(ying)用過(guo)程中(zhong)為了使(shi)(shi)2507雙相(xiang)不(bu)銹鋼獲(huo)得較好的(de)(de)綜合(he)性能(neng)，進行(xing)固(gu)(gu)溶(rong)(rong)(rong)處(chu)理時(shi)選取的(de)(de)固(gu)(gu)溶(rong)(rong)(rong)溫度應(ying)(ying)該在1050~1100℃之間(jian)。
2507雙(shuang)(shuang)(shuang)相(xiang)(xiang)(xiang)不(bu)銹(xiu)(xiu)(xiu)鋼(gang)分(fen)別(bie)在(zai)1000℃、1050℃、1100℃、1150℃、1200℃固(gu)(gu)溶(rong)(rong)(rong)(rong)0.5h后(hou)(hou)水冷的(de)(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)值(zhi)如圖3.6所示。從(cong)圖3.6可知(zhi)DSS2507的(de)(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)隨(sui)(sui)固(gu)(gu)溶(rong)(rong)(rong)(rong)處理(li)溫(wen)度(du)(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)(de)(de)升(sheng)(sheng)(sheng)高(gao)(gao)(gao)先減小(xiao)后(hou)(hou)變大(da)呈(cheng)曲線變化。在(zai)1000~1050℃溫(wen)度(du)(du)(du)(du)(du)(du)(du)范圍(wei)內鋼(gang)的(de)(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)隨(sui)(sui)固(gu)(gu)溶(rong)(rong)(rong)(rong)熱(re)(re)處理(li)溫(wen)度(du)(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)(de)(de)增(zeng)高(gao)(gao)(gao)而逐漸減小(xiao)，1050~1200℃范圍(wei)內隨(sui)(sui)固(gu)(gu)溶(rong)(rong)(rong)(rong)熱(re)(re)處理(li)溫(wen)度(du)(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)(de)(de)上(shang)升(sheng)(sheng)(sheng)硬(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)又漸漸變大(da)，且1050℃時(shi)DSS2507的(de)(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)表現為(wei)最小(xiao)。從(cong)3.2.1節分(fen)析可知(zhi)當固(gu)(gu)溶(rong)(rong)(rong)(rong)溫(wen)度(du)(du)(du)(du)(du)(du)(du)為(wei)1000℃時(shi)在(zai)鐵(tie)素(su)(su)體(ti)(ti)和奧氏(shi)體(ti)(ti)相(xiang)(xiang)(xiang)界(jie)處有(you)σ相(xiang)(xiang)(xiang)析出，σ相(xiang)(xiang)(xiang)是(shi)一種硬(ying)(ying)而脆(cui)的(de)(de)(de)(de)(de)(de)(de)(de)相(xiang)(xiang)(xiang)，能夠(gou)提高(gao)(gao)(gao)雙(shuang)(shuang)(shuang)相(xiang)(xiang)(xiang)不(bu)銹(xiu)(xiu)(xiu)鋼(gang)的(de)(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)值(zhi)，所以1000℃下鋼(gang)有(you)較高(gao)(gao)(gao)的(de)(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)，而σ相(xiang)(xiang)(xiang)會(hui)隨(sui)(sui)固(gu)(gu)溶(rong)(rong)(rong)(rong)熱(re)(re)處理(li)溫(wen)度(du)(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)(de)(de)升(sheng)(sheng)(sheng)高(gao)(gao)(gao)而漸漸溶(rong)(rong)(rong)(rong)解到基體(ti)(ti)中(zhong)，DSS2507的(de)(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)有(you)下降(jiang)的(de)(de)(de)(de)(de)(de)(de)(de)趨(qu)勢(shi)；同時(shi)又由于(yu)(yu)固(gu)(gu)溶(rong)(rong)(rong)(rong)熱(re)(re)處理(li)溫(wen)度(du)(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)(de)(de)增(zeng)高(gao)(gao)(gao)導致(zhi)鋼(gang)中(zhong)的(de)(de)(de)(de)(de)(de)(de)(de)鐵(tie)素(su)(su)體(ti)(ti)相(xiang)(xiang)(xiang)量增(zeng)加而奧氏(shi)體(ti)(ti)相(xiang)(xiang)(xiang)量降(jiang)低(di)，在(zai)室溫(wen)下鐵(tie)素(su)(su)體(ti)(ti)是(shi)體(ti)(ti)心立方(fang)(fang)結構（bcc)奧氏(shi)體(ti)(ti)是(shi)面心立方(fang)(fang)結構（fcc),前者硬(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)要高(gao)(gao)(gao)于(yu)(yu)后(hou)(hou)者，因(yin)此在(zai)鐵(tie)素(su)(su)體(ti)(ti)含(han)量逐漸升(sheng)(sheng)(sheng)高(gao)(gao)(gao)的(de)(de)(de)(de)(de)(de)(de)(de)情況下鋼(gang)的(de)(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)也(ye)逐漸升(sheng)(sheng)(sheng)高(gao)(gao)(gao)，即隨(sui)(sui)著固(gu)(gu)溶(rong)(rong)(rong)(rong)溫(wen)度(du)(du)(du)(du)(du)(du)(du)的(de)(de)(de)(de)(de)(de)(de)(de)升(sheng)(sheng)(sheng)高(gao)(gao)(gao)2507 雙(shuang)(shuang)(shuang)相(xiang)(xiang)(xiang)不(bu)銹(xiu)(xiu)(xiu)鋼(gang)的(de)(de)(de)(de)(de)(de)(de)(de)硬(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)呈(cheng)升(sheng)(sheng)(sheng)高(gao)(gao)(gao)的(de)(de)(de)(de)(de)(de)(de)(de)趨(qu)勢(shi)。綜(zong)上(shang)所述，隨(sui)(sui)固(gu)(gu)溶(rong)(rong)(rong)(rong)溫(wen)度(du)(du)(du)(du)(du)(du)(du)從(cong)1000℃上(shang)升(sheng)(sheng)(sheng)到1200℃,2507雙(shuang)(shuang)(shuang)相(xiang)(xiang)(xiang)不(bu)銹(xiu)(xiu)(xiu)鋼(gang)硬(ying)(ying)度(du)(du)(du)(du)(du)(du)(du)呈(cheng)先降(jiang)低(di)后(hou)(hou)升(sheng)(sheng)(sheng)高(gao)(gao)(gao)的(de)(de)(de)(de)(de)(de)(de)(de)變化趨(qu)勢(shi)。
