20#精密鋼管批發零售

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　　20#精(jing)密鋼管熱處理工藝(yi)

　　精密鋼管前奏

　　真(zhen)空退(tui)火優質彈簧鋼(gang)、工具(ju)鋼(gang)、精密鋼(gang)管的(de)絲材，不銹鋼(gang)制品及鈦合(he)金材，作光亮退(tui)火均(jun)可采(cai)用(yong)(yong)真(zhen)空處理。退(tui)火溫(wen)度(du)(du)愈低，則(ze)要求真(zhen)空度(du)(du)愈高(gao)。為(wei)防止鉻的(de)蒸(zheng)發及加速(su)熱(re)傳(chuan)導，一般采(cai)用(yong)(yong)載氣加熱(re)(保溫(wen))法(fa)，并注意對(dui)不銹鋼(gang)和鈦合(he)金不宜(yi)用(yong)(yong)氮(dan)而應采(cai)用(yong)(yong)氬氣。

　　精密鋼管過程

　　真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)爐按(an)冷(leng)(leng)(leng)(leng)(leng)卻方法分為(wei)(wei)油淬(cui)(cui)(cui)(cui)(cui)和氣(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)兩類，按(an)工(gong)位(wei)數分為(wei)(wei)單室式(shi)和雙室式(shi)，904山(shan)\畏嘲均屬周期(qi)式(shi)作(zuo)業(ye)爐。真(zhen)(zhen)空(kong)油淬(cui)(cui)(cui)(cui)(cui)爐都(dou)是雙室的(de)(de)(de)(de)(de)(de)，后(hou)室置電加(jia)(jia)熱(re)元(yuan)件(jian)，前室的(de)(de)(de)(de)(de)(de)下(xia)(xia)方置油槽(cao)。工(gong)件(jian)完成加(jia)(jia)熱(re)、保溫(wen)后(hou)移入(ru)前室，關(guan)閉中門后(hou)向前室充(chong)入(ru)惰(duo)性氣(qi)(qi)(qi)至大(da)約2.66%26times;lO ～1.01%26times;10 Pa(200～760mm汞柱)，入(ru)油。油淬(cui)(cui)(cui)(cui)(cui)易引起(qi)(qi)工(gong)件(jian)表面(mian)變(bian)質。由于(yu)表面(mian)活(huo)性大(da)，在短暫的(de)(de)(de)(de)(de)(de)高溫(wen)油膜作(zuo)用(yong)下(xia)(xia)即可發(fa)生(sheng)顯(xian)著薄層(ceng)滲(shen)碳(tan)，此(ci)外，碳(tan)黑(hei)和油在表面(mian)的(de)(de)(de)(de)(de)(de)粘附對簡化熱(re)處(chu)理流程很(hen)不(bu)利。真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)技術的(de)(de)(de)(de)(de)(de)發(fa)展(zhan)主要(yao)在于(yu)研制性能優良、工(gong)位(wei)單一(yi)(yi)(yi)的(de)(de)(de)(de)(de)(de)氣(qi)(qi)(qi)冷(leng)(leng)(leng)(leng)(leng)淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)爐。前述雙室式(shi)爐亦可用(yong)于(yu)氣(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(在前室噴氣(qi)(qi)(qi)冷(leng)(leng)(leng)(leng)(leng)卻)，但雙工(gong)位(wei)式(shi)的(de)(de)(de)(de)(de)(de)操作(zuo)使(shi)大(da)批量裝爐的(de)(de)(de)(de)(de)(de)生(sheng)產(chan)發(fa)生(sheng)困難，也易在高溫(wen)移動中引起(qi)(qi)工(gong)件(jian)變(bian)形或改(gai)變(bian)工(gong)件(jian)方位(wei)增加(jia)(jia)淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)變(bian)形。單一(yi)(yi)(yi)工(gong)位(wei)的(de)(de)(de)(de)(de)(de)氣(qi)(qi)(qi)冷(leng)(leng)(leng)(leng)(leng)淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)爐是在加(jia)(jia)熱(re)保溫(wen)完成后(hou)在加(jia)(jia)熱(re)室內噴氣(qi)(qi)(qi)冷(leng)(leng)(leng)(leng)(leng)卻。氣(qi)(qi)(qi)冷(leng)(leng)(leng)(leng)(leng)的(de)(de)(de)(de)(de)(de)冷(leng)(leng)(leng)(leng)(leng)速不(bu)如油冷(leng)(leng)(leng)(leng)(leng)快，也低(di)于(yu)傳統淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)法中的(de)(de)(de)(de)(de)(de)熔鹽等溫(wen)、分級淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)。因而(er)，不(bu)斷提高噴冷(leng)(leng)(leng)(leng)(leng)室壓(ya)(ya)力(li)，增大(da)流量，以(yi)及采用(yong)摩爾質量比氮(dan)和氬小的(de)(de)(de)(de)(de)(de)惰(duo)性氣(qi)(qi)(qi)體氦和氫(qing)，是當(dang)今真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)技術發(fa)展(zhan)的(de)(de)(de)(de)(de)(de)主流。70年(nian)代(dai)后(hou)期(qi)將氮(dan)氣(qi)(qi)(qi)噴冷(leng)(leng)(leng)(leng)(leng)的(de)(de)(de)(de)(de)(de)壓(ya)(ya)力(li)從(cong)(1～2)%26times;10Pa提高到(dao)(5～6)%26times;10Pa，使(shi)冷(leng)(leng)(leng)(leng)(leng)卻能力(li)接(jie)近于(yu)常壓(ya)(ya)下(xia)(xia)的(de)(de)(de)(de)(de)(de)油冷(leng)(leng)(leng)(leng)(leng)。80年(nian)代(dai)中期(qi)出現超高壓(ya)(ya)氣(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)，用(yong)(10～20)%26times;10Pa的(de)(de)(de)(de)(de)(de)氦，冷(leng)(leng)(leng)(leng)(leng)卻能力(li)等于(yu)或略高于(yu)油淬(cui)(cui)(cui)(cui)(cui)，已(yi)進入(ru)工(gong)業(ye)實(shi)用(yong)。90年(nian)代(dai)初采用(yong)40%26times;10Pa的(de)(de)(de)(de)(de)(de)氫(qing)氣(qi)(qi)(qi)，接(jie)近水(shui)淬(cui)(cui)(cui)(cui)(cui)的(de)(de)(de)(de)(de)(de)冷(leng)(leng)(leng)(leng)(leng)卻能力(li)，尚處(chu)于(yu)起(qi)(qi)步階段。工(gong)業(ye)發(fa)達(da)國(guo)家(jia)已(yi)進展(zhan)到(dao)以(yi)高壓(ya)(ya)(5～6)%26times;10。Pa氣(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)為(wei)(wei)主體，而(er)中國(guo)產(chan)氣(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)一(yi)(yi)(yi)些金屬的(de)(de)(de)(de)(de)(de)蒸氣(qi)(qi)(qi)壓(ya)(ya)(理論(lun)值(zhi))與溫(wen)度(du)的(de)(de)(de)(de)(de)(de)關(guan)系則(ze)尚處(chu)于(yu)一(yi)(yi)(yi)般加(jia)(jia)壓(ya)(ya)氣(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(2%26times;10Pa)型階段。

　　結果真空滲(shen)(shen)(shen)碳(tan)為真空滲(shen)(shen)(shen)碳(tan)一淬(cui)(cui)火工(gong)藝(yi)曲線。在真空中(zhong)加熱到(dao)滲(shen)(shen)(shen)碳(tan)溫(wen)(wen)度(du)并保溫(wen)(wen)使表(biao)面凈化(hua)、活化(hua)之后，通(tong)入(ru)(ru)稀薄滲(shen)(shen)(shen)碳(tan)富化(hua)氣(qi)(qi)(見控制(zhi)氣(qi)(qi)氛熱處(chu)理)，在大(da)約1330Pa(10T0rr)負(fu)壓下進行(xing)滲(shen)(shen)(shen)入(ru)(ru)，然(ran)后停(ting)氣(qi)(qi)(降壓)進行(xing)擴(kuo)散。滲(shen)(shen)(shen)碳(tan)后的(de)精密鋼管淬(cui)(cui)火采(cai)用(yong)一次(ci)淬(cui)(cui)火法，即先停(ting)電，通(tong)氮冷(leng)卻工(gong)件至(zhi)臨界點A，、以下，使內部(bu)發生相變(bian)，再(zai)停(ting)氣(qi)(qi)、開泵，升溫(wen)(wen)到(dao)Ac1，～Accm之間。淬(cui)(cui)冷(leng)方法可(ke)(ke)(ke)采(cai)用(yong)氣(qi)(qi)冷(leng)或油(you)冷(leng)。后者為奧氏體(ti)(ti)化(hua)后移入(ru)(ru)前室(shi)，充氮至(zhi)常壓，入(ru)(ru)油(you)。真空滲(shen)(shen)(shen)碳(tan)的(de)溫(wen)(wen)度(du)一般高(gao)于(yu)普(pu)通(tong)氣(qi)(qi)體(ti)(ti)滲(shen)(shen)(shen)碳(tan)，常采(cai)用(yong)920～1040℃滲(shen)(shen)(shen)入(ru)(ru)和擴(kuo)散可(ke)(ke)(ke)按所(suo)示分兩階段(duan)，也可(ke)(ke)(ke)用(yong)脈沖式通(tong)氣(qi)(qi)、停(ting)氣(qi)(qi)，多段(duan)式的(de)滲(shen)(shen)(shen)一擴(kuo)相間，效果更好。由(you)于(yu)溫(wen)(wen)度(du)高(gao)，尤其表(biao)面潔凈、有活性，真空滲(shen)(shen)(shen)碳(tan)層(ceng)形成速(su)度(du)比普(pu)通(tong)氣(qi)(qi)體(ti)(ti)、液體(ti)(ti)和固體(ti)(ti)滲(shen)(shen)(shen)碳(tan)快，如(ru)要求滲(shen)(shen)(shen)層(ceng)為1mm時(shi)，在927℃只需5h，而1033℃僅需1h。

　　精(jing)密鋼(gang)管硬度與變形

　　取兩(liang)塊(kuai)式(shi)樣，一塊(kuai)用于研(yan)究不(bu)同形(xing)變程度(du)對(dui)硬(ying)度(du)的影響(xiang)，另一塊(kuai)研(yan)究不(bu)同溫(wen)度(du)對(dui)性能(neng)的影響(xiang)。

　　冷(leng)(leng)變(bian)(bian)形(xing)強(qiang)化(hua)在(zai)(zai)實際生產(chan)中(zhong)具有(you)重(zhong)要的(de)意義。首先這是一(yi)種重(zhong)要的(de)強(qiang)化(hua)材料(liao)的(de)手段(duan)，尤其對用熱處理不(bu)(bu)能強(qiang)化(hua)的(de)材料(liao)來(lai)說(shuo)，顯得更為(wei)(wei)重(zhong)要。其次，冷(leng)(leng)變(bian)(bian)形(xing)強(qiang)化(hua)有(you)利于金屬的(de)變(bian)(bian)形(xing)均勻。因為(wei)(wei)精(jing)密(mi)鋼(gang)管的(de)變(bian)(bian)形(xing)部(bu)分產(chan)生硬化(hua)，將使(shi)變(bian)(bian)形(xing)向未(wei)變(bian)(bian)形(xing)或變(bian)(bian)形(xing)較少的(de)部(bu)分繼續(xu)發(fa)展。第(di)三，冷(leng)(leng)變(bian)(bian)形(xing)強(qiang)化(hua)可以(yi)提高(gao)構件在(zai)(zai)使(shi)用過(guo)程中(zhong)的(de)安全性(xing)，構件一(yi)旦超載，產(chan)生塑性(xing)變(bian)(bian)形(xing)，由(you)于強(qiang)化(hua)作用，可防止(zhi)構件突然斷裂(lie)。但是，冷(leng)(leng)變(bian)(bian)形(xing)強(qiang)化(hua)也給精(jing)密(mi)鋼(gang)管的(de)繼續(xu)變(bian)(bian)形(xing)帶來(lai)困難，甚至出(chu)現裂(lie)紋。因此，在(zai)(zai)精(jing)密(mi)鋼(gang)管變(bian)(bian)形(xing)和加工過(guo)程中(zhong)常進行"中(zhong)間退火"，以(yi)消除(chu)它的(de)不(bu)(bu)利影(ying)響。