20#精密鋼管批發零售

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　　20#精密鋼管熱處理工(gong)藝

　　精密鋼管前奏

　　真空(kong)(kong)退(tui)(tui)火優質彈簧鋼(gang)(gang)、工具鋼(gang)(gang)、精(jing)密鋼(gang)(gang)管的(de)絲材，不(bu)銹鋼(gang)(gang)制(zhi)品及(ji)鈦合金材，作光(guang)亮(liang)退(tui)(tui)火均可采用真空(kong)(kong)處理。退(tui)(tui)火溫度愈(yu)低，則要求真空(kong)(kong)度愈(yu)高。為防(fang)止鉻(ge)的(de)蒸發及(ji)加速熱傳導，一般采用載氣加熱(保(bao)溫)法，并(bing)注意對不(bu)銹鋼(gang)(gang)和鈦合金不(bu)宜用氮(dan)而應采用氬氣。

　　精密鋼管過程

　　真(zhen)(zhen)(zhen)空淬(cui)火(huo)(huo)(huo)真(zhen)(zhen)(zhen)空淬(cui)火(huo)(huo)(huo)爐(lu)(lu)按冷(leng)(leng)卻(que)(que)方(fang)法分為油(you)(you)(you)(you)(you)淬(cui)和(he)(he)氣(qi)(qi)(qi)(qi)淬(cui)兩類(lei)，按工(gong)位(wei)(wei)數(shu)分為單(dan)室(shi)(shi)式(shi)和(he)(he)雙室(shi)(shi)式(shi)，904山\畏嘲均屬(shu)周期式(shi)作業(ye)爐(lu)(lu)。真(zhen)(zhen)(zhen)空油(you)(you)(you)(you)(you)淬(cui)爐(lu)(lu)都是雙室(shi)(shi)的(de)(de)(de)(de)(de)，后(hou)室(shi)(shi)置電加(jia)熱(re)(re)元(yuan)件，前(qian)室(shi)(shi)的(de)(de)(de)(de)(de)下(xia)方(fang)置油(you)(you)(you)(you)(you)槽。工(gong)件完成(cheng)加(jia)熱(re)(re)、保溫(wen)后(hou)移入前(qian)室(shi)(shi)，關閉中門(men)后(hou)向(xiang)前(qian)室(shi)(shi)充入惰性氣(qi)(qi)(qi)(qi)至大(da)約2.66%26times;lO ～1.01%26times;10 Pa(200～760mm汞柱)，入油(you)(you)(you)(you)(you)。油(you)(you)(you)(you)(you)淬(cui)易引起工(gong)件表(biao)面變質。由于(yu)(yu)(yu)(yu)表(biao)面活性大(da)，在(zai)短(duan)暫的(de)(de)(de)(de)(de)高溫(wen)油(you)(you)(you)(you)(you)膜(mo)作用(yong)(yong)下(xia)即可發(fa)生(sheng)(sheng)顯(xian)著(zhu)薄層(ceng)滲碳，此外(wai)，碳黑和(he)(he)油(you)(you)(you)(you)(you)在(zai)表(biao)面的(de)(de)(de)(de)(de)粘附對簡化熱(re)(re)處理(li)流(liu)程很不利。真(zhen)(zhen)(zhen)空淬(cui)火(huo)(huo)(huo)技術(shu)的(de)(de)(de)(de)(de)發(fa)展主要在(zai)于(yu)(yu)(yu)(yu)研制性能(neng)(neng)優良、工(gong)位(wei)(wei)單(dan)一的(de)(de)(de)(de)(de)氣(qi)(qi)(qi)(qi)冷(leng)(leng)淬(cui)火(huo)(huo)(huo)爐(lu)(lu)。前(qian)述(shu)雙室(shi)(shi)式(shi)爐(lu)(lu)亦可用(yong)(yong)于(yu)(yu)(yu)(yu)氣(qi)(qi)(qi)(qi)淬(cui)(在(zai)前(qian)室(shi)(shi)噴(pen)(pen)(pen)氣(qi)(qi)(qi)(qi)冷(leng)(leng)卻(que)(que))，但(dan)雙工(gong)位(wei)(wei)式(shi)的(de)(de)(de)(de)(de)操作使大(da)批(pi)量裝爐(lu)(lu)的(de)(de)(de)(de)(de)生(sheng)(sheng)產(chan)發(fa)生(sheng)(sheng)困難，也易在(zai)高溫(wen)移動中引起工(gong)件變形(xing)或改變工(gong)件方(fang)位(wei)(wei)增加(jia)淬(cui)火(huo)(huo)(huo)變形(xing)。單(dan)一工(gong)位(wei)(wei)的(de)(de)(de)(de)(de)氣(qi)(qi)(qi)(qi)冷(leng)(leng)淬(cui)火(huo)(huo)(huo)爐(lu)(lu)是在(zai)加(jia)熱(re)(re)保溫(wen)完成(cheng)后(hou)在(zai)加(jia)熱(re)(re)室(shi)(shi)內噴(pen)(pen)(pen)氣(qi)(qi)(qi)(qi)冷(leng)(leng)卻(que)(que)。氣(qi)(qi)(qi)(qi)冷(leng)(leng)的(de)(de)(de)(de)(de)冷(leng)(leng)速不如油(you)(you)(you)(you)(you)冷(leng)(leng)快，也低于(yu)(yu)(yu)(yu)傳統淬(cui)火(huo)(huo)(huo)法中的(de)(de)(de)(de)(de)熔鹽等溫(wen)、分級淬(cui)火(huo)(huo)(huo)。因而，不斷(duan)提高噴(pen)(pen)(pen)冷(leng)(leng)室(shi)(shi)壓(ya)力，增大(da)流(liu)量，以及采(cai)用(yong)(yong)摩爾質量比氮和(he)(he)氬小的(de)(de)(de)(de)(de)惰性氣(qi)(qi)(qi)(qi)體(ti)氦(hai)和(he)(he)氫(qing)，是當(dang)今(jin)真(zhen)(zhen)(zhen)空淬(cui)火(huo)(huo)(huo)技術(shu)發(fa)展的(de)(de)(de)(de)(de)主流(liu)。70年代(dai)后(hou)期將氮氣(qi)(qi)(qi)(qi)噴(pen)(pen)(pen)冷(leng)(leng)的(de)(de)(de)(de)(de)壓(ya)力從(1～2)%26times;10Pa提高到(5～6)%26times;10Pa，使冷(leng)(leng)卻(que)(que)能(neng)(neng)力接近(jin)于(yu)(yu)(yu)(yu)常壓(ya)下(xia)的(de)(de)(de)(de)(de)油(you)(you)(you)(you)(you)冷(leng)(leng)。80年代(dai)中期出現超高壓(ya)氣(qi)(qi)(qi)(qi)淬(cui)，用(yong)(yong)(10～20)%26times;10Pa的(de)(de)(de)(de)(de)氦(hai)，冷(leng)(leng)卻(que)(que)能(neng)(neng)力等于(yu)(yu)(yu)(yu)或略高于(yu)(yu)(yu)(yu)油(you)(you)(you)(you)(you)淬(cui)，已進入工(gong)業(ye)實用(yong)(yong)。90年代(dai)初(chu)采(cai)用(yong)(yong)40%26times;10Pa的(de)(de)(de)(de)(de)氫(qing)氣(qi)(qi)(qi)(qi)，接近(jin)水淬(cui)的(de)(de)(de)(de)(de)冷(leng)(leng)卻(que)(que)能(neng)(neng)力，尚(shang)處于(yu)(yu)(yu)(yu)起步(bu)階(jie)段。工(gong)業(ye)發(fa)達國(guo)家已進展到以高壓(ya)(5～6)%26times;10。Pa氣(qi)(qi)(qi)(qi)淬(cui)為主體(ti)，而中國(guo)產(chan)氣(qi)(qi)(qi)(qi)淬(cui)一些金屬(shu)的(de)(de)(de)(de)(de)蒸(zheng)氣(qi)(qi)(qi)(qi)壓(ya)(理(li)論值)與(yu)溫(wen)度的(de)(de)(de)(de)(de)關系則尚(shang)處于(yu)(yu)(yu)(yu)一般加(jia)壓(ya)氣(qi)(qi)(qi)(qi)淬(cui)(2%26times;10Pa)型階(jie)段。

　　結果(guo)真(zhen)(zhen)空(kong)(kong)滲(shen)(shen)(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)為(wei)真(zhen)(zhen)空(kong)(kong)滲(shen)(shen)(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)一(yi)淬(cui)火(huo)工(gong)藝曲線(xian)。在真(zhen)(zhen)空(kong)(kong)中加(jia)熱到滲(shen)(shen)(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)溫(wen)度(du)并保溫(wen)使表(biao)面(mian)凈化(hua)、活(huo)(huo)化(hua)之(zhi)后(hou)(hou)，通(tong)(tong)入(ru)(ru)稀薄滲(shen)(shen)(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)富化(hua)氣(qi)(qi)(qi)(qi)(見(jian)控制氣(qi)(qi)(qi)(qi)氛熱處(chu)理)，在大約1330Pa(10T0rr)負壓下進行(xing)滲(shen)(shen)(shen)(shen)(shen)(shen)入(ru)(ru)，然(ran)后(hou)(hou)停氣(qi)(qi)(qi)(qi)(降壓)進行(xing)擴散。滲(shen)(shen)(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)后(hou)(hou)的精(jing)密鋼管淬(cui)火(huo)采用(yong)一(yi)次淬(cui)火(huo)法(fa)，即先停電，通(tong)(tong)氮冷(leng)卻(que)工(gong)件至(zhi)臨界(jie)點A，、以下，使內(nei)部(bu)發生相變，再(zai)停氣(qi)(qi)(qi)(qi)、開泵，升溫(wen)到Ac1，～Accm之(zhi)間。淬(cui)冷(leng)方法(fa)可(ke)(ke)采用(yong)氣(qi)(qi)(qi)(qi)冷(leng)或油冷(leng)。后(hou)(hou)者為(wei)奧(ao)氏體(ti)化(hua)后(hou)(hou)移入(ru)(ru)前室，充氮至(zhi)常(chang)壓，入(ru)(ru)油。真(zhen)(zhen)空(kong)(kong)滲(shen)(shen)(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)的溫(wen)度(du)一(yi)般高(gao)于普通(tong)(tong)氣(qi)(qi)(qi)(qi)體(ti)滲(shen)(shen)(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)，常(chang)采用(yong)920～1040℃滲(shen)(shen)(shen)(shen)(shen)(shen)入(ru)(ru)和(he)擴散可(ke)(ke)按(an)所示分兩階段(duan)，也可(ke)(ke)用(yong)脈沖式通(tong)(tong)氣(qi)(qi)(qi)(qi)、停氣(qi)(qi)(qi)(qi)，多段(duan)式的滲(shen)(shen)(shen)(shen)(shen)(shen)一(yi)擴相間，效果(guo)更(geng)好(hao)。由于溫(wen)度(du)高(gao)，尤其(qi)表(biao)面(mian)潔凈、有活(huo)(huo)性，真(zhen)(zhen)空(kong)(kong)滲(shen)(shen)(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)層(ceng)形成速(su)度(du)比普通(tong)(tong)氣(qi)(qi)(qi)(qi)體(ti)、液體(ti)和(he)固體(ti)滲(shen)(shen)(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)快，如(ru)要求滲(shen)(shen)(shen)(shen)(shen)(shen)層(ceng)為(wei)1mm時(shi)，在927℃只需(xu)5h，而(er)1033℃僅(jin)需(xu)1h。

　　精密鋼管(guan)硬度與變形

　　取兩塊(kuai)式(shi)樣(yang)，一塊(kuai)用于(yu)研究不同(tong)形變程度(du)(du)對(dui)硬(ying)度(du)(du)的影響(xiang)(xiang)，另一塊(kuai)研究不同(tong)溫度(du)(du)對(dui)性能的影響(xiang)(xiang)。

　　冷(leng)(leng)變(bian)(bian)(bian)形(xing)強(qiang)(qiang)化(hua)(hua)在(zai)實際生產中具有(you)重要(yao)的(de)(de)意(yi)義。首先這是一種重要(yao)的(de)(de)強(qiang)(qiang)化(hua)(hua)材料的(de)(de)手段(duan)，尤其對(dui)用熱處(chu)理不(bu)能(neng)強(qiang)(qiang)化(hua)(hua)的(de)(de)材料來說，顯得更(geng)為重要(yao)。其次，冷(leng)(leng)變(bian)(bian)(bian)形(xing)強(qiang)(qiang)化(hua)(hua)有(you)利于金屬的(de)(de)變(bian)(bian)(bian)形(xing)均勻。因為精密(mi)鋼(gang)(gang)(gang)管的(de)(de)變(bian)(bian)(bian)形(xing)部(bu)分產生硬化(hua)(hua)，將使變(bian)(bian)(bian)形(xing)向(xiang)未變(bian)(bian)(bian)形(xing)或變(bian)(bian)(bian)形(xing)較少(shao)的(de)(de)部(bu)分繼續發展(zhan)。第(di)三，冷(leng)(leng)變(bian)(bian)(bian)形(xing)強(qiang)(qiang)化(hua)(hua)可(ke)以提高構件(jian)在(zai)使用過程中的(de)(de)安全性，構件(jian)一旦超(chao)載，產生塑性變(bian)(bian)(bian)形(xing)，由(you)于強(qiang)(qiang)化(hua)(hua)作用，可(ke)防止(zhi)構件(jian)突(tu)然斷裂(lie)。但是，冷(leng)(leng)變(bian)(bian)(bian)形(xing)強(qiang)(qiang)化(hua)(hua)也給精密(mi)鋼(gang)(gang)(gang)管的(de)(de)繼續變(bian)(bian)(bian)形(xing)帶來困(kun)難，甚至出現(xian)裂(lie)紋。因此，在(zai)精密(mi)鋼(gang)(gang)(gang)管變(bian)(bian)(bian)形(xing)和加工過程中常進行"中間退火"，以消除它的(de)(de)不(bu)利影響。