20#精密鋼管批發零售

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　　20#精密鋼管熱(re)處(chu)理工藝

　　精密鋼管前奏

　　真(zhen)空退火優質彈簧(huang)鋼(gang)(gang)、工具鋼(gang)(gang)、精密鋼(gang)(gang)管的絲材(cai)，不(bu)(bu)銹鋼(gang)(gang)制品(pin)及鈦(tai)合(he)金(jin)材(cai)，作光亮退火均可采用(yong)真(zhen)空處理。退火溫度(du)愈低，則要求(qiu)真(zhen)空度(du)愈高。為防止鉻的蒸發及加速(su)熱(re)傳導，一般采用(yong)載氣(qi)加熱(re)(保溫)法(fa)，并注意對不(bu)(bu)銹鋼(gang)(gang)和鈦(tai)合(he)金(jin)不(bu)(bu)宜用(yong)氮而應采用(yong)氬氣(qi)。

　　精密鋼管過程

　　真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)爐(lu)(lu)按(an)冷(leng)(leng)(leng)卻(que)方法(fa)(fa)分(fen)為(wei)(wei)油(you)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)和(he)(he)氣(qi)(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)兩類，按(an)工(gong)(gong)位數分(fen)為(wei)(wei)單(dan)室(shi)(shi)式和(he)(he)雙室(shi)(shi)式，904山\畏嘲均屬(shu)周期(qi)(qi)式作(zuo)業(ye)爐(lu)(lu)。真(zhen)(zhen)空(kong)油(you)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)爐(lu)(lu)都(dou)是雙室(shi)(shi)的(de)，后(hou)室(shi)(shi)置電(dian)加(jia)熱(re)元(yuan)件(jian)，前(qian)(qian)(qian)室(shi)(shi)的(de)下方置油(you)槽。工(gong)(gong)件(jian)完成加(jia)熱(re)、保溫(wen)(wen)后(hou)移入(ru)前(qian)(qian)(qian)室(shi)(shi)，關閉中(zhong)門(men)后(hou)向(xiang)前(qian)(qian)(qian)室(shi)(shi)充入(ru)惰性氣(qi)(qi)(qi)(qi)(qi)(qi)至大約2.66%26times;lO ～1.01%26times;10 Pa(200～760mm汞柱)，入(ru)油(you)。油(you)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)易引起(qi)工(gong)(gong)件(jian)表(biao)(biao)面變質。由于(yu)(yu)表(biao)(biao)面活性大，在(zai)(zai)短暫(zan)的(de)高溫(wen)(wen)油(you)膜作(zuo)用(yong)下即可發(fa)生(sheng)顯著薄層滲碳，此外，碳黑(hei)和(he)(he)油(you)在(zai)(zai)表(biao)(biao)面的(de)粘附(fu)對(dui)簡化熱(re)處理流(liu)(liu)程很不利。真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)技(ji)術(shu)的(de)發(fa)展主(zhu)要在(zai)(zai)于(yu)(yu)研制性能(neng)(neng)(neng)優良、工(gong)(gong)位單(dan)一的(de)氣(qi)(qi)(qi)(qi)(qi)(qi)冷(leng)(leng)(leng)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)爐(lu)(lu)。前(qian)(qian)(qian)述(shu)雙室(shi)(shi)式爐(lu)(lu)亦(yi)可用(yong)于(yu)(yu)氣(qi)(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)(在(zai)(zai)前(qian)(qian)(qian)室(shi)(shi)噴(pen)氣(qi)(qi)(qi)(qi)(qi)(qi)冷(leng)(leng)(leng)卻(que))，但雙工(gong)(gong)位式的(de)操作(zuo)使(shi)大批量(liang)(liang)(liang)裝爐(lu)(lu)的(de)生(sheng)產(chan)發(fa)生(sheng)困難(nan)，也易在(zai)(zai)高溫(wen)(wen)移動中(zhong)引起(qi)工(gong)(gong)件(jian)變形或(huo)改變工(gong)(gong)件(jian)方位增加(jia)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)變形。單(dan)一工(gong)(gong)位的(de)氣(qi)(qi)(qi)(qi)(qi)(qi)冷(leng)(leng)(leng)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)爐(lu)(lu)是在(zai)(zai)加(jia)熱(re)保溫(wen)(wen)完成后(hou)在(zai)(zai)加(jia)熱(re)室(shi)(shi)內(nei)噴(pen)氣(qi)(qi)(qi)(qi)(qi)(qi)冷(leng)(leng)(leng)卻(que)。氣(qi)(qi)(qi)(qi)(qi)(qi)冷(leng)(leng)(leng)的(de)冷(leng)(leng)(leng)速不如(ru)油(you)冷(leng)(leng)(leng)快，也低(di)于(yu)(yu)傳統淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)法(fa)(fa)中(zhong)的(de)熔鹽等溫(wen)(wen)、分(fen)級淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)。因(yin)而(er)，不斷提(ti)(ti)高噴(pen)冷(leng)(leng)(leng)室(shi)(shi)壓(ya)力，增大流(liu)(liu)量(liang)(liang)(liang)，以及采用(yong)摩(mo)爾(er)質量(liang)(liang)(liang)比氮和(he)(he)氬小的(de)惰性氣(qi)(qi)(qi)(qi)(qi)(qi)體(ti)氦(hai)(hai)和(he)(he)氫(qing)，是當今(jin)真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)技(ji)術(shu)發(fa)展的(de)主(zhu)流(liu)(liu)。70年代(dai)后(hou)期(qi)(qi)將氮氣(qi)(qi)(qi)(qi)(qi)(qi)噴(pen)冷(leng)(leng)(leng)的(de)壓(ya)力從(1～2)%26times;10Pa提(ti)(ti)高到(5～6)%26times;10Pa，使(shi)冷(leng)(leng)(leng)卻(que)能(neng)(neng)(neng)力接近于(yu)(yu)常壓(ya)下的(de)油(you)冷(leng)(leng)(leng)。80年代(dai)中(zhong)期(qi)(qi)出現超高壓(ya)氣(qi)(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)，用(yong)(10～20)%26times;10Pa的(de)氦(hai)(hai)，冷(leng)(leng)(leng)卻(que)能(neng)(neng)(neng)力等于(yu)(yu)或(huo)略高于(yu)(yu)油(you)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)，已進入(ru)工(gong)(gong)業(ye)實用(yong)。90年代(dai)初采用(yong)40%26times;10Pa的(de)氫(qing)氣(qi)(qi)(qi)(qi)(qi)(qi)，接近水(shui)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)的(de)冷(leng)(leng)(leng)卻(que)能(neng)(neng)(neng)力，尚處于(yu)(yu)起(qi)步階(jie)段(duan)。工(gong)(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)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)為(wei)(wei)主(zhu)體(ti)，而(er)中(zhong)國(guo)產(chan)氣(qi)(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)一些金屬(shu)的(de)蒸氣(qi)(qi)(qi)(qi)(qi)(qi)壓(ya)(理論值(zhi))與溫(wen)(wen)度的(de)關系(xi)則尚處于(yu)(yu)一般加(jia)壓(ya)氣(qi)(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(cui)(cui)(2%26times;10Pa)型階(jie)段(duan)。

　　結果(guo)真(zhen)空(kong)滲碳(tan)(tan)為真(zhen)空(kong)滲碳(tan)(tan)一淬火(huo)工(gong)藝曲線。在(zai)(zai)真(zhen)空(kong)中加熱到滲碳(tan)(tan)溫(wen)(wen)度(du)并(bing)保(bao)溫(wen)(wen)使表面凈化、活化之后，通入稀(xi)薄滲碳(tan)(tan)富化氣(qi)(qi)(qi)(見控制氣(qi)(qi)(qi)氛(fen)熱處(chu)理)，在(zai)(zai)大(da)約1330Pa(10T0rr)負壓下(xia)進行(xing)滲入，然后停(ting)氣(qi)(qi)(qi)(降壓)進行(xing)擴(kuo)(kuo)(kuo)散。滲碳(tan)(tan)后的精密(mi)鋼管淬火(huo)采用(yong)(yong)一次淬火(huo)法(fa)，即先停(ting)電，通氮冷(leng)卻工(gong)件至臨界點A，、以下(xia)，使內(nei)部(bu)發生相變，再停(ting)氣(qi)(qi)(qi)、開泵(beng)，升溫(wen)(wen)到Ac1，～Accm之間(jian)。淬冷(leng)方法(fa)可(ke)采用(yong)(yong)氣(qi)(qi)(qi)冷(leng)或油冷(leng)。后者(zhe)為奧氏體(ti)(ti)化后移入前(qian)室(shi)，充氮至常(chang)壓，入油。真(zhen)空(kong)滲碳(tan)(tan)的溫(wen)(wen)度(du)一般高于普(pu)通氣(qi)(qi)(qi)體(ti)(ti)滲碳(tan)(tan)，常(chang)采用(yong)(yong)920～1040℃滲入和擴(kuo)(kuo)(kuo)散可(ke)按所示分兩(liang)階段，也可(ke)用(yong)(yong)脈沖式通氣(qi)(qi)(qi)、停(ting)氣(qi)(qi)(qi)，多段式的滲一擴(kuo)(kuo)(kuo)相間(jian)，效果(guo)更好。由于溫(wen)(wen)度(du)高，尤其表面潔凈、有活性，真(zhen)空(kong)滲碳(tan)(tan)層形成速度(du)比普(pu)通氣(qi)(qi)(qi)體(ti)(ti)、液體(ti)(ti)和固體(ti)(ti)滲碳(tan)(tan)快，如要求滲層為1mm時，在(zai)(zai)927℃只(zhi)需(xu)(xu)5h，而1033℃僅需(xu)(xu)1h。

　　精密鋼管硬度與變形

　　取兩塊(kuai)(kuai)式樣，一(yi)塊(kuai)(kuai)用于研(yan)究(jiu)不(bu)同(tong)形變程度對硬度的(de)影響，另一(yi)塊(kuai)(kuai)研(yan)究(jiu)不(bu)同(tong)溫度對性能的(de)影響。

　　冷(leng)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)強(qiang)(qiang)化(hua)在實際生產(chan)中(zhong)具(ju)有重(zhong)要(yao)的(de)(de)(de)意義。首先(xian)這是一(yi)種重(zhong)要(yao)的(de)(de)(de)強(qiang)(qiang)化(hua)材料的(de)(de)(de)手段，尤其對用熱處理(li)不能強(qiang)(qiang)化(hua)的(de)(de)(de)材料來(lai)說，顯得更為重(zhong)要(yao)。其次，冷(leng)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)強(qiang)(qiang)化(hua)有利于金屬的(de)(de)(de)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)均(jun)勻。因為精(jing)(jing)密鋼管的(de)(de)(de)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)部分產(chan)生硬化(hua)，將(jiang)使(shi)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)向未變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)或變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)較少的(de)(de)(de)部分繼續發展。第三(san)，冷(leng)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)強(qiang)(qiang)化(hua)可以(yi)提高構件在使(shi)用過(guo)程中(zhong)的(de)(de)(de)安全(quan)性，構件一(yi)旦超載，產(chan)生塑性變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)，由(you)于強(qiang)(qiang)化(hua)作(zuo)用，可防止構件突然(ran)斷(duan)裂。但是，冷(leng)變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)強(qiang)(qiang)化(hua)也給精(jing)(jing)密鋼管的(de)(de)(de)繼續變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)帶來(lai)困(kun)難(nan)，甚至出現裂紋。因此(ci)，在精(jing)(jing)密鋼管變(bian)(bian)(bian)(bian)形(xing)(xing)(xing)和加(jia)工(gong)過(guo)程中(zhong)常進(jin)行"中(zhong)間(jian)退火"，以(yi)消除它的(de)(de)(de)不利影響。