20#精密鋼管批發零售

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　　20#精(jing)密(mi)鋼管(guan)熱(re)處理(li)工藝

　　精密鋼管前奏

　　真空(kong)退火(huo)優質彈簧鋼(gang)(gang)、工具(ju)鋼(gang)(gang)、精密鋼(gang)(gang)管的絲材，不銹鋼(gang)(gang)制品及鈦合金(jin)材，作光亮退火(huo)均可采用(yong)真空(kong)處(chu)理。退火(huo)溫(wen)度(du)愈(yu)低，則要求真空(kong)度(du)愈(yu)高。為防止鉻的蒸發(fa)及加速(su)熱傳(chuan)導，一般采用(yong)載氣加熱(保溫(wen))法，并注意對(dui)不銹鋼(gang)(gang)和鈦合金(jin)不宜(yi)用(yong)氮而應采用(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)爐按冷(leng)(leng)(leng)(leng)卻方法分為油(you)(you)淬(cui)(cui)(cui)(cui)(cui)和(he)氣(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)兩類(lei)，按工位數分為單室(shi)(shi)(shi)(shi)式和(he)雙(shuang)(shuang)室(shi)(shi)(shi)(shi)式，904山\畏(wei)嘲均屬周期(qi)(qi)式作業(ye)(ye)爐。真(zhen)(zhen)空(kong)油(you)(you)淬(cui)(cui)(cui)(cui)(cui)爐都(dou)是雙(shuang)(shuang)室(shi)(shi)(shi)(shi)的(de)(de)(de)(de)(de)，后室(shi)(shi)(shi)(shi)置(zhi)電加熱(re)元(yuan)件，前室(shi)(shi)(shi)(shi)的(de)(de)(de)(de)(de)下(xia)方置(zhi)油(you)(you)槽。工件完成加熱(re)、保(bao)溫(wen)后移(yi)入前室(shi)(shi)(shi)(shi)，關閉中(zhong)門后向前室(shi)(shi)(shi)(shi)充入惰性(xing)氣(qi)(qi)(qi)(qi)(qi)至大約(yue)2.66%26times;lO ～1.01%26times;10 Pa(200～760mm汞柱)，入油(you)(you)。油(you)(you)淬(cui)(cui)(cui)(cui)(cui)易(yi)引(yin)起工件表面變(bian)質。由于(yu)表面活性(xing)大，在(zai)短暫的(de)(de)(de)(de)(de)高溫(wen)油(you)(you)膜作用下(xia)即可發(fa)(fa)(fa)生顯著薄層滲(shen)碳，此(ci)外，碳黑和(he)油(you)(you)在(zai)表面的(de)(de)(de)(de)(de)粘附對簡化熱(re)處理流(liu)程很不(bu)(bu)利。真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)技術的(de)(de)(de)(de)(de)發(fa)(fa)(fa)展(zhan)(zhan)主(zhu)要(yao)在(zai)于(yu)研制性(xing)能(neng)優良、工位單一(yi)的(de)(de)(de)(de)(de)氣(qi)(qi)(qi)(qi)(qi)冷(leng)(leng)(leng)(leng)淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)爐。前述雙(shuang)(shuang)室(shi)(shi)(shi)(shi)式爐亦可用于(yu)氣(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(在(zai)前室(shi)(shi)(shi)(shi)噴(pen)氣(qi)(qi)(qi)(qi)(qi)冷(leng)(leng)(leng)(leng)卻)，但雙(shuang)(shuang)工位式的(de)(de)(de)(de)(de)操作使大批量裝爐的(de)(de)(de)(de)(de)生產(chan)發(fa)(fa)(fa)生困難，也(ye)易(yi)在(zai)高溫(wen)移(yi)動中(zhong)引(yin)起工件變(bian)形或改(gai)變(bian)工件方位增加淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)變(bian)形。單一(yi)工位的(de)(de)(de)(de)(de)氣(qi)(qi)(qi)(qi)(qi)冷(leng)(leng)(leng)(leng)淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)爐是在(zai)加熱(re)保(bao)溫(wen)完成后在(zai)加熱(re)室(shi)(shi)(shi)(shi)內噴(pen)氣(qi)(qi)(qi)(qi)(qi)冷(leng)(leng)(leng)(leng)卻。氣(qi)(qi)(qi)(qi)(qi)冷(leng)(leng)(leng)(leng)的(de)(de)(de)(de)(de)冷(leng)(leng)(leng)(leng)速不(bu)(bu)如油(you)(you)冷(leng)(leng)(leng)(leng)快(kuai)，也(ye)低于(yu)傳(chuan)統淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)法中(zhong)的(de)(de)(de)(de)(de)熔鹽(yan)等溫(wen)、分級(ji)淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)。因而(er)，不(bu)(bu)斷(duan)提高噴(pen)冷(leng)(leng)(leng)(leng)室(shi)(shi)(shi)(shi)壓(ya)力(li)(li)，增大流(liu)量，以(yi)及采用摩(mo)爾質量比氮和(he)氬小(xiao)的(de)(de)(de)(de)(de)惰性(xing)氣(qi)(qi)(qi)(qi)(qi)體氦和(he)氫(qing)，是當(dang)今(jin)真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)(cui)火(huo)(huo)技術發(fa)(fa)(fa)展(zhan)(zhan)的(de)(de)(de)(de)(de)主(zhu)流(liu)。70年代(dai)(dai)后期(qi)(qi)將氮氣(qi)(qi)(qi)(qi)(qi)噴(pen)冷(leng)(leng)(leng)(leng)的(de)(de)(de)(de)(de)壓(ya)力(li)(li)從(1～2)%26times;10Pa提高到(5～6)%26times;10Pa，使冷(leng)(leng)(leng)(leng)卻能(neng)力(li)(li)接近于(yu)常(chang)壓(ya)下(xia)的(de)(de)(de)(de)(de)油(you)(you)冷(leng)(leng)(leng)(leng)。80年代(dai)(dai)中(zhong)期(qi)(qi)出現超高壓(ya)氣(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)，用(10～20)%26times;10Pa的(de)(de)(de)(de)(de)氦，冷(leng)(leng)(leng)(leng)卻能(neng)力(li)(li)等于(yu)或略高于(yu)油(you)(you)淬(cui)(cui)(cui)(cui)(cui)，已進入工業(ye)(ye)實用。90年代(dai)(dai)初采用40%26times;10Pa的(de)(de)(de)(de)(de)氫(qing)氣(qi)(qi)(qi)(qi)(qi)，接近水(shui)淬(cui)(cui)(cui)(cui)(cui)的(de)(de)(de)(de)(de)冷(leng)(leng)(leng)(leng)卻能(neng)力(li)(li)，尚(shang)處于(yu)起步階段。工業(ye)(ye)發(fa)(fa)(fa)達(da)國家已進展(zhan)(zhan)到以(yi)高壓(ya)(5～6)%26times;10。Pa氣(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)為主(zhu)體，而(er)中(zhong)國產(chan)氣(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)一(yi)些金屬的(de)(de)(de)(de)(de)蒸氣(qi)(qi)(qi)(qi)(qi)壓(ya)(理論(lun)值(zhi))與溫(wen)度(du)的(de)(de)(de)(de)(de)關系則尚(shang)處于(yu)一(yi)般加壓(ya)氣(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(2%26times;10Pa)型階段。

　　結果(guo)(guo)真(zhen)空(kong)(kong)(kong)(kong)滲(shen)(shen)(shen)碳為(wei)真(zhen)空(kong)(kong)(kong)(kong)滲(shen)(shen)(shen)碳一(yi)(yi)淬火工藝曲線(xian)。在(zai)(zai)真(zhen)空(kong)(kong)(kong)(kong)中加(jia)熱到(dao)滲(shen)(shen)(shen)碳溫(wen)度并保溫(wen)使表面凈化、活(huo)化之(zhi)后，通入稀薄(bo)滲(shen)(shen)(shen)碳富化氣(qi)(qi)(qi)(見(jian)控制氣(qi)(qi)(qi)氛熱處理)，在(zai)(zai)大約1330Pa(10T0rr)負壓(ya)下(xia)進行滲(shen)(shen)(shen)入，然后停氣(qi)(qi)(qi)(降壓(ya))進行擴散(san)。滲(shen)(shen)(shen)碳后的精密鋼管(guan)淬火采(cai)用一(yi)(yi)次淬火法，即先停電(dian)，通氮冷(leng)卻工件至臨(lin)界點A，、以下(xia)，使內(nei)部發生相變，再(zai)停氣(qi)(qi)(qi)、開泵，升溫(wen)到(dao)Ac1，～Accm之(zhi)間(jian)。淬冷(leng)方法可采(cai)用氣(qi)(qi)(qi)冷(leng)或油冷(leng)。后者為(wei)奧氏體化后移入前室，充氮至常壓(ya)，入油。真(zhen)空(kong)(kong)(kong)(kong)滲(shen)(shen)(shen)碳的溫(wen)度一(yi)(yi)般高于普通氣(qi)(qi)(qi)體滲(shen)(shen)(shen)碳，常采(cai)用920～1040℃滲(shen)(shen)(shen)入和擴散(san)可按(an)所(suo)示(shi)分兩階段，也(ye)可用脈沖式通氣(qi)(qi)(qi)、停氣(qi)(qi)(qi)，多段式的滲(shen)(shen)(shen)一(yi)(yi)擴相間(jian)，效果(guo)(guo)更好。由(you)于溫(wen)度高，尤其(qi)表面潔凈、有活(huo)性，真(zhen)空(kong)(kong)(kong)(kong)滲(shen)(shen)(shen)碳層(ceng)形成(cheng)速度比普通氣(qi)(qi)(qi)體、液體和固體滲(shen)(shen)(shen)碳快，如(ru)要求滲(shen)(shen)(shen)層(ceng)為(wei)1mm時，在(zai)(zai)927℃只需(xu)5h，而1033℃僅需(xu)1h。

　　精密鋼管硬(ying)度(du)與變形

　　取兩塊(kuai)式樣，一塊(kuai)用于研究(jiu)不同(tong)形變(bian)程度對(dui)(dui)硬度的(de)影響，另一塊(kuai)研究(jiu)不同(tong)溫(wen)度對(dui)(dui)性(xing)能的(de)影響。

　　冷(leng)變(bian)(bian)形(xing)(xing)強(qiang)化在(zai)實際生產(chan)(chan)中具有重(zhong)(zhong)要的意義。首先這是(shi)一種重(zhong)(zhong)要的強(qiang)化材料(liao)的手段，尤其對用(yong)熱處理不能強(qiang)化的材料(liao)來(lai)說，顯得更為(wei)(wei)重(zhong)(zhong)要。其次，冷(leng)變(bian)(bian)形(xing)(xing)強(qiang)化有利于金屬(shu)的變(bian)(bian)形(xing)(xing)均(jun)勻(yun)。因為(wei)(wei)精密(mi)鋼管的變(bian)(bian)形(xing)(xing)部分(fen)(fen)產(chan)(chan)生硬化，將使(shi)變(bian)(bian)形(xing)(xing)向未變(bian)(bian)形(xing)(xing)或變(bian)(bian)形(xing)(xing)較少的部分(fen)(fen)繼(ji)續(xu)發(fa)展(zhan)。第(di)三，冷(leng)變(bian)(bian)形(xing)(xing)強(qiang)化可以提(ti)高構(gou)件(jian)在(zai)使(shi)用(yong)過(guo)程(cheng)中的安全性，構(gou)件(jian)一旦超載，產(chan)(chan)生塑性變(bian)(bian)形(xing)(xing)，由(you)于強(qiang)化作用(yong)，可防止構(gou)件(jian)突然斷(duan)裂(lie)。但是(shi)，冷(leng)變(bian)(bian)形(xing)(xing)強(qiang)化也給精密(mi)鋼管的繼(ji)續(xu)變(bian)(bian)形(xing)(xing)帶來(lai)困難，甚至(zhi)出現(xian)裂(lie)紋。因此，在(zai)精密(mi)鋼管變(bian)(bian)形(xing)(xing)和加工過(guo)程(cheng)中常(chang)進行"中間退火"，以消除它的不利影響(xiang)。