20#精密鋼管批發零售

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　　20#精密鋼(gang)管熱處理工藝

　　精密鋼管前奏

　　真(zhen)空退火(huo)優質彈簧鋼、工具鋼、精密(mi)鋼管(guan)的(de)絲材(cai)，不(bu)銹鋼制品及鈦合金材(cai)，作光亮(liang)退火(huo)均可采用真(zhen)空處(chu)理(li)。退火(huo)溫(wen)度(du)愈低，則要求真(zhen)空度(du)愈高。為防止鉻的(de)蒸(zheng)發及加速熱(re)傳導，一般采用載(zai)氣加熱(re)(保(bao)溫(wen))法，并注(zhu)意對不(bu)銹鋼和鈦合金不(bu)宜用氮而(er)應采用氬(ya)氣。

　　精密鋼管過程

　　真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)火(huo)(huo)真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)火(huo)(huo)爐按(an)冷(leng)(leng)卻(que)方(fang)(fang)法(fa)分(fen)為(wei)油(you)(you)淬(cui)(cui)(cui)(cui)和(he)氣(qi)(qi)淬(cui)(cui)(cui)(cui)兩類(lei)，按(an)工(gong)(gong)(gong)位(wei)數(shu)分(fen)為(wei)單(dan)室(shi)式(shi)(shi)和(he)雙(shuang)室(shi)式(shi)(shi)，904山\畏(wei)嘲(chao)均屬周期式(shi)(shi)作業爐。真(zhen)(zhen)空(kong)油(you)(you)淬(cui)(cui)(cui)(cui)爐都是雙(shuang)室(shi)的(de)(de)，后(hou)(hou)室(shi)置(zhi)電加熱(re)(re)(re)元(yuan)件，前(qian)(qian)(qian)(qian)室(shi)的(de)(de)下(xia)方(fang)(fang)置(zhi)油(you)(you)槽(cao)。工(gong)(gong)(gong)件完(wan)(wan)成(cheng)(cheng)加熱(re)(re)(re)、保溫(wen)(wen)(wen)后(hou)(hou)移入前(qian)(qian)(qian)(qian)室(shi)，關(guan)閉中(zhong)門后(hou)(hou)向前(qian)(qian)(qian)(qian)室(shi)充入惰性(xing)氣(qi)(qi)至(zhi)大(da)約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)易(yi)引(yin)起工(gong)(gong)(gong)件表面變質。由(you)于(yu)表面活性(xing)大(da)，在(zai)(zai)(zai)短暫的(de)(de)高(gao)(gao)(gao)(gao)溫(wen)(wen)(wen)油(you)(you)膜作用(yong)下(xia)即可(ke)(ke)發生(sheng)顯(xian)著(zhu)薄層(ceng)滲碳(tan)，此外，碳(tan)黑和(he)油(you)(you)在(zai)(zai)(zai)表面的(de)(de)粘附(fu)對簡化熱(re)(re)(re)處(chu)理流(liu)(liu)程很不(bu)利。真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)火(huo)(huo)技(ji)術的(de)(de)發展(zhan)主要(yao)在(zai)(zai)(zai)于(yu)研制性(xing)能(neng)優良、工(gong)(gong)(gong)位(wei)單(dan)一(yi)的(de)(de)氣(qi)(qi)冷(leng)(leng)淬(cui)(cui)(cui)(cui)火(huo)(huo)爐。前(qian)(qian)(qian)(qian)述雙(shuang)室(shi)式(shi)(shi)爐亦可(ke)(ke)用(yong)于(yu)氣(qi)(qi)淬(cui)(cui)(cui)(cui)(在(zai)(zai)(zai)前(qian)(qian)(qian)(qian)室(shi)噴氣(qi)(qi)冷(leng)(leng)卻(que))，但雙(shuang)工(gong)(gong)(gong)位(wei)式(shi)(shi)的(de)(de)操作使大(da)批量裝爐的(de)(de)生(sheng)產發生(sheng)困難，也易(yi)在(zai)(zai)(zai)高(gao)(gao)(gao)(gao)溫(wen)(wen)(wen)移動中(zhong)引(yin)起工(gong)(gong)(gong)件變形或改變工(gong)(gong)(gong)件方(fang)(fang)位(wei)增加淬(cui)(cui)(cui)(cui)火(huo)(huo)變形。單(dan)一(yi)工(gong)(gong)(gong)位(wei)的(de)(de)氣(qi)(qi)冷(leng)(leng)淬(cui)(cui)(cui)(cui)火(huo)(huo)爐是在(zai)(zai)(zai)加熱(re)(re)(re)保溫(wen)(wen)(wen)完(wan)(wan)成(cheng)(cheng)后(hou)(hou)在(zai)(zai)(zai)加熱(re)(re)(re)室(shi)內噴氣(qi)(qi)冷(leng)(leng)卻(que)。氣(qi)(qi)冷(leng)(leng)的(de)(de)冷(leng)(leng)速不(bu)如油(you)(you)冷(leng)(leng)快，也低于(yu)傳(chuan)統淬(cui)(cui)(cui)(cui)火(huo)(huo)法(fa)中(zhong)的(de)(de)熔鹽等溫(wen)(wen)(wen)、分(fen)級淬(cui)(cui)(cui)(cui)火(huo)(huo)。因而，不(bu)斷提(ti)高(gao)(gao)(gao)(gao)噴冷(leng)(leng)室(shi)壓力(li)，增大(da)流(liu)(liu)量，以(yi)及采(cai)用(yong)摩爾質量比(bi)氮和(he)氬小的(de)(de)惰性(xing)氣(qi)(qi)體(ti)氦(hai)和(he)氫，是當(dang)今真(zhen)(zhen)空(kong)淬(cui)(cui)(cui)(cui)火(huo)(huo)技(ji)術發展(zhan)的(de)(de)主流(liu)(liu)。70年代(dai)后(hou)(hou)期將氮氣(qi)(qi)噴冷(leng)(leng)的(de)(de)壓力(li)從(1～2)%26times;10Pa提(ti)高(gao)(gao)(gao)(gao)到(dao)(5～6)%26times;10Pa，使冷(leng)(leng)卻(que)能(neng)力(li)接(jie)近于(yu)常壓下(xia)的(de)(de)油(you)(you)冷(leng)(leng)。80年代(dai)中(zhong)期出現超高(gao)(gao)(gao)(gao)壓氣(qi)(qi)淬(cui)(cui)(cui)(cui)，用(yong)(10～20)%26times;10Pa的(de)(de)氦(hai)，冷(leng)(leng)卻(que)能(neng)力(li)等于(yu)或略(lve)高(gao)(gao)(gao)(gao)于(yu)油(you)(you)淬(cui)(cui)(cui)(cui)，已(yi)(yi)進入工(gong)(gong)(gong)業實用(yong)。90年代(dai)初采(cai)用(yong)40%26times;10Pa的(de)(de)氫氣(qi)(qi)，接(jie)近水淬(cui)(cui)(cui)(cui)的(de)(de)冷(leng)(leng)卻(que)能(neng)力(li)，尚(shang)處(chu)于(yu)起步階段。工(gong)(gong)(gong)業發達國(guo)家(jia)已(yi)(yi)進展(zhan)到(dao)以(yi)高(gao)(gao)(gao)(gao)壓(5～6)%26times;10。Pa氣(qi)(qi)淬(cui)(cui)(cui)(cui)為(wei)主體(ti)，而中(zhong)國(guo)產氣(qi)(qi)淬(cui)(cui)(cui)(cui)一(yi)些金屬的(de)(de)蒸(zheng)氣(qi)(qi)壓(理論值)與溫(wen)(wen)(wen)度的(de)(de)關(guan)系則尚(shang)處(chu)于(yu)一(yi)般加壓氣(qi)(qi)淬(cui)(cui)(cui)(cui)(2%26times;10Pa)型階段。

　　結果(guo)真(zhen)(zhen)空(kong)(kong)滲(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)為(wei)真(zhen)(zhen)空(kong)(kong)滲(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)一(yi)淬(cui)(cui)火(huo)工藝曲線。在真(zhen)(zhen)空(kong)(kong)中加熱到滲(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)溫度并保溫使表面凈(jing)化(hua)、活化(hua)之后(hou)，通(tong)入(ru)稀薄滲(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)富化(hua)氣(qi)(qi)(見(jian)控制氣(qi)(qi)氛(fen)熱處(chu)理(li))，在大(da)約1330Pa(10T0rr)負壓下進(jin)行(xing)滲(shen)(shen)(shen)(shen)入(ru)，然后(hou)停(ting)氣(qi)(qi)(降壓)進(jin)行(xing)擴散(san)。滲(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)后(hou)的精(jing)密鋼(gang)管淬(cui)(cui)火(huo)采用一(yi)次淬(cui)(cui)火(huo)法，即先停(ting)電(dian)，通(tong)氮冷(leng)卻(que)工件至(zhi)臨界點A，、以下，使內部發生相變，再停(ting)氣(qi)(qi)、開(kai)泵，升溫到Ac1，～Accm之間。淬(cui)(cui)冷(leng)方法可采用氣(qi)(qi)冷(leng)或油冷(leng)。后(hou)者為(wei)奧氏體化(hua)后(hou)移(yi)入(ru)前室，充氮至(zhi)常(chang)壓，入(ru)油。真(zhen)(zhen)空(kong)(kong)滲(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)的溫度一(yi)般高(gao)于(yu)普通(tong)氣(qi)(qi)體滲(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)，常(chang)采用920～1040℃滲(shen)(shen)(shen)(shen)入(ru)和擴散(san)可按所示分兩階段，也(ye)可用脈沖式(shi)(shi)通(tong)氣(qi)(qi)、停(ting)氣(qi)(qi)，多段式(shi)(shi)的滲(shen)(shen)(shen)(shen)一(yi)擴相間，效果(guo)更好。由于(yu)溫度高(gao)，尤(you)其表面潔凈(jing)、有活性，真(zhen)(zhen)空(kong)(kong)滲(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)層形成速度比(bi)普通(tong)氣(qi)(qi)體、液體和固體滲(shen)(shen)(shen)(shen)碳(tan)(tan)(tan)快，如要求滲(shen)(shen)(shen)(shen)層為(wei)1mm時，在927℃只需5h，而1033℃僅需1h。

　　精密鋼管硬度與(yu)變形

　　取兩塊式樣(yang)，一塊用于(yu)研究不同形(xing)變程度對硬度的影響，另一塊研究不同溫(wen)度對性能的影響。

　　冷變(bian)形強化(hua)在實(shi)際生(sheng)產中(zhong)具有重要(yao)的(de)(de)意義。首先(xian)這是一種重要(yao)的(de)(de)強化(hua)材料的(de)(de)手段，尤其對(dui)用熱處理(li)不能強化(hua)的(de)(de)材料來說，顯得更為重要(yao)。其次，冷變(bian)形強化(hua)有利于金屬的(de)(de)變(bian)形均勻。因(yin)為精(jing)(jing)密(mi)鋼管的(de)(de)變(bian)形部分(fen)產生(sheng)硬化(hua)，將使變(bian)形向未(wei)變(bian)形或變(bian)形較少的(de)(de)部分(fen)繼續(xu)發展。第三，冷變(bian)形強化(hua)可(ke)以提高構(gou)件在使用過程中(zhong)的(de)(de)安(an)全性，構(gou)件一旦超載，產生(sheng)塑性變(bian)形，由于強化(hua)作用，可(ke)防止構(gou)件突然斷裂。但(dan)是，冷變(bian)形強化(hua)也(ye)給精(jing)(jing)密(mi)鋼管的(de)(de)繼續(xu)變(bian)形帶(dai)來困難，甚至出現裂紋。因(yin)此，在精(jing)(jing)密(mi)鋼管變(bian)形和(he)加工(gong)過程中(zhong)常進行"中(zhong)間退火(huo)"，以消除(chu)它的(de)(de)不利影響。