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(tui)火優(you)質彈簧鋼、工具(ju)鋼、精密鋼管(guan)的絲(si)材，不銹(xiu)鋼制品(pin)及(ji)鈦合金材，作光亮退(tui)火均可采(cai)用(yong)真(zhen)空處(chu)理。退(tui)火溫度愈低，則要求真(zhen)空度愈高。為防止鉻的蒸發及(ji)加(jia)速熱(re)傳(chuan)導(dao)，一般采(cai)用(yong)載氣加(jia)熱(re)(保(bao)溫)法，并注意對不銹(xiu)鋼和鈦合金不宜用(yong)氮(dan)而應采(cai)用(yong)氬(ya)氣。

　　精密鋼管過程

　　真(zhen)(zhen)空淬(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)真(zhen)(zhen)空淬(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)爐(lu)按冷(leng)卻(que)方法分為(wei)(wei)油(you)淬(cui)(cui)(cui)(cui)(cui)(cui)和(he)氣(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(cui)兩類，按工(gong)位數分為(wei)(wei)單室(shi)(shi)(shi)(shi)(shi)式(shi)和(he)雙(shuang)室(shi)(shi)(shi)(shi)(shi)式(shi)，904山\畏嘲均屬周期(qi)式(shi)作(zuo)(zuo)業(ye)爐(lu)。真(zhen)(zhen)空油(you)淬(cui)(cui)(cui)(cui)(cui)(cui)爐(lu)都是(shi)雙(shuang)室(shi)(shi)(shi)(shi)(shi)的(de)(de)(de)(de)(de)(de)，后室(shi)(shi)(shi)(shi)(shi)置(zhi)電加熱(re)元件(jian)，前(qian)室(shi)(shi)(shi)(shi)(shi)的(de)(de)(de)(de)(de)(de)下方置(zhi)油(you)槽(cao)。工(gong)件(jian)完成加熱(re)、保溫后移(yi)入(ru)(ru)前(qian)室(shi)(shi)(shi)(shi)(shi)，關閉中門后向前(qian)室(shi)(shi)(shi)(shi)(shi)充入(ru)(ru)惰性(xing)氣(qi)(qi)(qi)(qi)(qi)至大(da)約(yue)2.66%26times;lO ～1.01%26times;10 Pa(200～760mm汞柱)，入(ru)(ru)油(you)。油(you)淬(cui)(cui)(cui)(cui)(cui)(cui)易(yi)引(yin)起工(gong)件(jian)表面(mian)變(bian)質。由于(yu)表面(mian)活性(xing)大(da)，在(zai)(zai)(zai)(zai)(zai)短暫(zan)的(de)(de)(de)(de)(de)(de)高(gao)溫油(you)膜作(zuo)(zuo)用(yong)(yong)(yong)下即可發生顯(xian)著薄層(ceng)滲碳(tan)，此外，碳(tan)黑和(he)油(you)在(zai)(zai)(zai)(zai)(zai)表面(mian)的(de)(de)(de)(de)(de)(de)粘附對簡化熱(re)處理(li)(li)流程很不(bu)(bu)(bu)利。真(zhen)(zhen)空淬(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)技(ji)術的(de)(de)(de)(de)(de)(de)發展主要在(zai)(zai)(zai)(zai)(zai)于(yu)研(yan)制性(xing)能優良(liang)、工(gong)位單一的(de)(de)(de)(de)(de)(de)氣(qi)(qi)(qi)(qi)(qi)冷(leng)淬(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)爐(lu)。前(qian)述(shu)雙(shuang)室(shi)(shi)(shi)(shi)(shi)式(shi)爐(lu)亦可用(yong)(yong)(yong)于(yu)氣(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(cui)(在(zai)(zai)(zai)(zai)(zai)前(qian)室(shi)(shi)(shi)(shi)(shi)噴氣(qi)(qi)(qi)(qi)(qi)冷(leng)卻(que))，但雙(shuang)工(gong)位式(shi)的(de)(de)(de)(de)(de)(de)操作(zuo)(zuo)使(shi)大(da)批(pi)量裝(zhuang)爐(lu)的(de)(de)(de)(de)(de)(de)生產(chan)發生困難，也易(yi)在(zai)(zai)(zai)(zai)(zai)高(gao)溫移(yi)動中引(yin)起工(gong)件(jian)變(bian)形(xing)或(huo)改變(bian)工(gong)件(jian)方位增加淬(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)變(bian)形(xing)。單一工(gong)位的(de)(de)(de)(de)(de)(de)氣(qi)(qi)(qi)(qi)(qi)冷(leng)淬(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)爐(lu)是(shi)在(zai)(zai)(zai)(zai)(zai)加熱(re)保溫完成后在(zai)(zai)(zai)(zai)(zai)加熱(re)室(shi)(shi)(shi)(shi)(shi)內噴氣(qi)(qi)(qi)(qi)(qi)冷(leng)卻(que)。氣(qi)(qi)(qi)(qi)(qi)冷(leng)的(de)(de)(de)(de)(de)(de)冷(leng)速不(bu)(bu)(bu)如油(you)冷(leng)快，也低于(yu)傳統淬(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)法中的(de)(de)(de)(de)(de)(de)熔鹽等(deng)溫、分級淬(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)。因而(er)，不(bu)(bu)(bu)斷提(ti)高(gao)噴冷(leng)室(shi)(shi)(shi)(shi)(shi)壓力(li)(li)(li)，增大(da)流量，以及(ji)采(cai)用(yong)(yong)(yong)摩(mo)爾質量比氮和(he)氬(ya)小的(de)(de)(de)(de)(de)(de)惰性(xing)氣(qi)(qi)(qi)(qi)(qi)體氦和(he)氫，是(shi)當今真(zhen)(zhen)空淬(cui)(cui)(cui)(cui)(cui)(cui)火(huo)(huo)(huo)(huo)技(ji)術發展的(de)(de)(de)(de)(de)(de)主流。70年代(dai)后期(qi)將氮氣(qi)(qi)(qi)(qi)(qi)噴冷(leng)的(de)(de)(de)(de)(de)(de)壓力(li)(li)(li)從(cong)(1～2)%26times;10Pa提(ti)高(gao)到(dao)(5～6)%26times;10Pa，使(shi)冷(leng)卻(que)能力(li)(li)(li)接近于(yu)常(chang)壓下的(de)(de)(de)(de)(de)(de)油(you)冷(leng)。80年代(dai)中期(qi)出現超高(gao)壓氣(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(cui)，用(yong)(yong)(yong)(10～20)%26times;10Pa的(de)(de)(de)(de)(de)(de)氦，冷(leng)卻(que)能力(li)(li)(li)等(deng)于(yu)或(huo)略高(gao)于(yu)油(you)淬(cui)(cui)(cui)(cui)(cui)(cui)，已(yi)(yi)進入(ru)(ru)工(gong)業(ye)實用(yong)(yong)(yong)。90年代(dai)初采(cai)用(yong)(yong)(yong)40%26times;10Pa的(de)(de)(de)(de)(de)(de)氫氣(qi)(qi)(qi)(qi)(qi)，接近水(shui)淬(cui)(cui)(cui)(cui)(cui)(cui)的(de)(de)(de)(de)(de)(de)冷(leng)卻(que)能力(li)(li)(li)，尚(shang)(shang)處于(yu)起步(bu)階段(duan)。工(gong)業(ye)發達(da)國家(jia)已(yi)(yi)進展到(dao)以高(gao)壓(5～6)%26times;10。Pa氣(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(cui)為(wei)(wei)主體，而(er)中國產(chan)氣(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(cui)一些金屬的(de)(de)(de)(de)(de)(de)蒸氣(qi)(qi)(qi)(qi)(qi)壓(理(li)(li)論值)與溫度(du)的(de)(de)(de)(de)(de)(de)關系則尚(shang)(shang)處于(yu)一般加壓氣(qi)(qi)(qi)(qi)(qi)淬(cui)(cui)(cui)(cui)(cui)(cui)(2%26times;10Pa)型階段(duan)。

　　結(jie)果(guo)真(zhen)空(kong)滲(shen)(shen)碳(tan)(tan)(tan)為(wei)真(zhen)空(kong)滲(shen)(shen)碳(tan)(tan)(tan)一淬火工藝曲線。在真(zhen)空(kong)中(zhong)加熱到滲(shen)(shen)碳(tan)(tan)(tan)溫(wen)度(du)并保溫(wen)使表面凈(jing)化(hua)、活(huo)化(hua)之后，通(tong)(tong)入(ru)稀薄(bo)滲(shen)(shen)碳(tan)(tan)(tan)富化(hua)氣(qi)(qi)(見控(kong)制氣(qi)(qi)氛熱處理)，在大約1330Pa(10T0rr)負壓(ya)下進行(xing)滲(shen)(shen)入(ru)，然(ran)后停(ting)(ting)氣(qi)(qi)(降壓(ya))進行(xing)擴(kuo)散。滲(shen)(shen)碳(tan)(tan)(tan)后的(de)(de)精密鋼管淬火采用(yong)一次(ci)淬火法(fa)(fa)，即先停(ting)(ting)電(dian)，通(tong)(tong)氮冷卻工件(jian)至臨界點A，、以下，使內(nei)部發生相(xiang)變(bian)，再停(ting)(ting)氣(qi)(qi)、開泵，升溫(wen)到Ac1，～Accm之間。淬冷方法(fa)(fa)可采用(yong)氣(qi)(qi)冷或油冷。后者為(wei)奧氏體化(hua)后移入(ru)前室，充氮至常壓(ya)，入(ru)油。真(zhen)空(kong)滲(shen)(shen)碳(tan)(tan)(tan)的(de)(de)溫(wen)度(du)一般高于普(pu)通(tong)(tong)氣(qi)(qi)體滲(shen)(shen)碳(tan)(tan)(tan)，常采用(yong)920～1040℃滲(shen)(shen)入(ru)和(he)擴(kuo)散可按(an)所示(shi)分兩階段，也可用(yong)脈沖(chong)式通(tong)(tong)氣(qi)(qi)、停(ting)(ting)氣(qi)(qi)，多(duo)段式的(de)(de)滲(shen)(shen)一擴(kuo)相(xiang)間，效果(guo)更好。由于溫(wen)度(du)高，尤其表面潔凈(jing)、有活(huo)性，真(zhen)空(kong)滲(shen)(shen)碳(tan)(tan)(tan)層形成速度(du)比普(pu)通(tong)(tong)氣(qi)(qi)體、液體和(he)固體滲(shen)(shen)碳(tan)(tan)(tan)快，如要求(qiu)滲(shen)(shen)層為(wei)1mm時，在927℃只(zhi)需5h，而1033℃僅需1h。

　　精密鋼(gang)管硬度與變形

　　取兩塊式樣，一塊用(yong)于(yu)研究不(bu)同形變(bian)程(cheng)度對硬度的影(ying)響，另一塊研究不(bu)同溫(wen)度對性能的影(ying)響。

　　冷(leng)(leng)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)強(qiang)(qiang)化(hua)(hua)(hua)在實際生(sheng)產(chan)中(zhong)具有(you)(you)重要(yao)的(de)(de)(de)(de)(de)意義。首先這(zhe)是(shi)一種(zhong)重要(yao)的(de)(de)(de)(de)(de)強(qiang)(qiang)化(hua)(hua)(hua)材(cai)料的(de)(de)(de)(de)(de)手段，尤其對用熱處理不能強(qiang)(qiang)化(hua)(hua)(hua)的(de)(de)(de)(de)(de)材(cai)料來說，顯得更為重要(yao)。其次(ci)，冷(leng)(leng)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)強(qiang)(qiang)化(hua)(hua)(hua)有(you)(you)利于(yu)金屬的(de)(de)(de)(de)(de)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)均勻(yun)。因為精密鋼管(guan)的(de)(de)(de)(de)(de)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)部分產(chan)生(sheng)硬化(hua)(hua)(hua)，將使變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)向未變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)或變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)較少的(de)(de)(de)(de)(de)部分繼(ji)續發展。第(di)三，冷(leng)(leng)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)強(qiang)(qiang)化(hua)(hua)(hua)可以(yi)提高構件(jian)在使用過(guo)程中(zhong)的(de)(de)(de)(de)(de)安全性，構件(jian)一旦超載，產(chan)生(sheng)塑性變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)，由(you)于(yu)強(qiang)(qiang)化(hua)(hua)(hua)作用，可防止構件(jian)突(tu)然(ran)斷裂。但(dan)是(shi)，冷(leng)(leng)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)強(qiang)(qiang)化(hua)(hua)(hua)也給精密鋼管(guan)的(de)(de)(de)(de)(de)繼(ji)續變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)帶來困難，甚至出現裂紋。因此(ci)，在精密鋼管(guan)變(bian)(bian)(bian)(bian)(bian)形(xing)(xing)和加工過(guo)程中(zhong)常進(jin)行"中(zhong)間退(tui)火(huo)"，以(yi)消除它(ta)的(de)(de)(de)(de)(de)不利影響。