20#精密鋼管批發零售
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牌號 | 化學成分% | |||||
C | Si | Mn | S | P | Cr | |
10 | 0.07-0.13 | 0.17-0.37 | 0.35-0.65 | ≤0.035 | ≤0.035 | |
20 | 0.17-0.23 | 0.17-0.37 | 0.35-0.65 | ≤0.035 | ≤0.035 | |
35 | 0.32-0.39 | 0.17-0.37 | 0.35-0.65 | ≤0.035 | ≤0.035 | |
45 | 0.42-0.50 | 0.17-0.37 | 0.50-0.80 | ≤0.035 | ≤0.035 | |
40Cr | 0.37-0.44 | 0.17-0.37 | 0.50-0.80 | ≤0.035 | ≤0.035 | 0.08-1.10 |
25Mn | 0.22-0.29 | 0.17-0.37 | 0.70-1.00 | ≤0.035 | ≤0.035 | ≤0.25 |
37Mn5 | 0.30-0.39 | 0.15-0.30 | 1.20-1.50 | ≤0.015 | ≤0.020 |
20#精(jing)密(mi)鋼管熱(re)處理工藝
精密鋼管前奏
真空退火(huo)優(you)質彈(dan)簧鋼、工具(ju)鋼、精密鋼管的絲(si)材,不銹鋼制品及鈦合金材,作光(guang)亮退火(huo)均可采(cai)(cai)用真空處理。退火(huo)溫度愈(yu)低,則要(yao)求(qiu)真空度愈(yu)高。為防止鉻(ge)的蒸發及加(jia)速熱傳導,一般采(cai)(cai)用載氣加(jia)熱(保溫)法,并注意對不銹鋼和鈦合金不宜(yi)用氮而應(ying)采(cai)(cai)用氬(ya)氣。
精密鋼管過程
真(zhen)(zhen)空(kong)淬(cui)(cui)火(huo)真(zhen)(zhen)空(kong)淬(cui)(cui)火(huo)爐(lu)(lu)按冷(leng)(leng)(leng)(leng)(leng)卻(que)(que)方法分為油(you)(you)(you)淬(cui)(cui)和氣(qi)(qi)淬(cui)(cui)兩類,按工(gong)(gong)位(wei)數分為單室(shi)式(shi)(shi)和雙(shuang)室(shi)式(shi)(shi),904山\畏嘲均(jun)屬周期(qi)式(shi)(shi)作業(ye)爐(lu)(lu)。真(zhen)(zhen)空(kong)油(you)(you)(you)淬(cui)(cui)爐(lu)(lu)都是(shi)雙(shuang)室(shi)的(de)(de)(de)(de),后(hou)室(shi)置(zhi)電加(jia)熱(re)元件(jian)(jian),前(qian)(qian)室(shi)的(de)(de)(de)(de)下(xia)(xia)方置(zhi)油(you)(you)(you)槽。工(gong)(gong)件(jian)(jian)完成加(jia)熱(re)、保溫后(hou)移(yi)入(ru)前(qian)(qian)室(shi),關閉(bi)中門后(hou)向前(qian)(qian)室(shi)充入(ru)惰性氣(qi)(qi)至(zhi)大(da)約2.66%26times;lO ~1.01%26times;10 Pa(200~760mm汞柱(zhu)),入(ru)油(you)(you)(you)。油(you)(you)(you)淬(cui)(cui)易引起工(gong)(gong)件(jian)(jian)表(biao)(biao)面變(bian)質。由于表(biao)(biao)面活性大(da),在短暫的(de)(de)(de)(de)高(gao)(gao)溫油(you)(you)(you)膜(mo)作用(yong)下(xia)(xia)即可發(fa)生(sheng)顯著(zhu)薄層滲碳,此外,碳黑(hei)和油(you)(you)(you)在表(biao)(biao)面的(de)(de)(de)(de)粘附對簡化(hua)熱(re)處理流(liu)程很不利。真(zhen)(zhen)空(kong)淬(cui)(cui)火(huo)技術(shu)(shu)的(de)(de)(de)(de)發(fa)展主(zhu)要(yao)在于研制(zhi)性能優良、工(gong)(gong)位(wei)單一(yi)的(de)(de)(de)(de)氣(qi)(qi)冷(leng)(leng)(leng)(leng)(leng)淬(cui)(cui)火(huo)爐(lu)(lu)。前(qian)(qian)述雙(shuang)室(shi)式(shi)(shi)爐(lu)(lu)亦可用(yong)于氣(qi)(qi)淬(cui)(cui)(在前(qian)(qian)室(shi)噴氣(qi)(qi)冷(leng)(leng)(leng)(leng)(leng)卻(que)(que)),但雙(shuang)工(gong)(gong)位(wei)式(shi)(shi)的(de)(de)(de)(de)操(cao)作使大(da)批量(liang)裝爐(lu)(lu)的(de)(de)(de)(de)生(sheng)產發(fa)生(sheng)困難,也(ye)(ye)易在高(gao)(gao)溫移(yi)動中引起工(gong)(gong)件(jian)(jian)變(bian)形(xing)或改(gai)變(bian)工(gong)(gong)件(jian)(jian)方位(wei)增加(jia)淬(cui)(cui)火(huo)變(bian)形(xing)。單一(yi)工(gong)(gong)位(wei)的(de)(de)(de)(de)氣(qi)(qi)冷(leng)(leng)(leng)(leng)(leng)淬(cui)(cui)火(huo)爐(lu)(lu)是(shi)在加(jia)熱(re)保溫完成后(hou)在加(jia)熱(re)室(shi)內(nei)噴氣(qi)(qi)冷(leng)(leng)(leng)(leng)(leng)卻(que)(que)。氣(qi)(qi)冷(leng)(leng)(leng)(leng)(leng)的(de)(de)(de)(de)冷(leng)(leng)(leng)(leng)(leng)速不如油(you)(you)(you)冷(leng)(leng)(leng)(leng)(leng)快,也(ye)(ye)低于傳統淬(cui)(cui)火(huo)法中的(de)(de)(de)(de)熔鹽(yan)等(deng)溫、分級淬(cui)(cui)火(huo)。因(yin)而,不斷提高(gao)(gao)噴冷(leng)(leng)(leng)(leng)(leng)室(shi)壓(ya)力,增大(da)流(liu)量(liang),以(yi)(yi)及采用(yong)摩爾質量(liang)比(bi)氮(dan)和氬小的(de)(de)(de)(de)惰性氣(qi)(qi)體氦(hai)和氫,是(shi)當今真(zhen)(zhen)空(kong)淬(cui)(cui)火(huo)技術(shu)(shu)發(fa)展的(de)(de)(de)(de)主(zhu)流(liu)。70年(nian)代(dai)后(hou)期(qi)將氮(dan)氣(qi)(qi)噴冷(leng)(leng)(leng)(leng)(leng)的(de)(de)(de)(de)壓(ya)力從(cong)(1~2)%26times;10Pa提高(gao)(gao)到(5~6)%26times;10Pa,使冷(leng)(leng)(leng)(leng)(leng)卻(que)(que)能力接近于常壓(ya)下(xia)(xia)的(de)(de)(de)(de)油(you)(you)(you)冷(leng)(leng)(leng)(leng)(leng)。80年(nian)代(dai)中期(qi)出現超(chao)高(gao)(gao)壓(ya)氣(qi)(qi)淬(cui)(cui),用(yong)(10~20)%26times;10Pa的(de)(de)(de)(de)氦(hai),冷(leng)(leng)(leng)(leng)(leng)卻(que)(que)能力等(deng)于或略高(gao)(gao)于油(you)(you)(you)淬(cui)(cui),已進入(ru)工(gong)(gong)業(ye)實用(yong)。90年(nian)代(dai)初采用(yong)40%26times;10Pa的(de)(de)(de)(de)氫氣(qi)(qi),接近水淬(cui)(cui)的(de)(de)(de)(de)冷(leng)(leng)(leng)(leng)(leng)卻(que)(que)能力,尚(shang)處于起步(bu)階段(duan)。工(gong)(gong)業(ye)發(fa)達國家(jia)已進展到以(yi)(yi)高(gao)(gao)壓(ya)(5~6)%26times;10。Pa氣(qi)(qi)淬(cui)(cui)為主(zhu)體,而中國產氣(qi)(qi)淬(cui)(cui)一(yi)些金屬的(de)(de)(de)(de)蒸氣(qi)(qi)壓(ya)(理論值)與溫度的(de)(de)(de)(de)關系則尚(shang)處于一(yi)般加(jia)壓(ya)氣(qi)(qi)淬(cui)(cui)(2%26times;10Pa)型階段(duan)。
結果真(zhen)(zhen)空(kong)滲(shen)(shen)碳(tan)(tan)(tan)為(wei)(wei)真(zhen)(zhen)空(kong)滲(shen)(shen)碳(tan)(tan)(tan)一淬(cui)火工藝曲線。在(zai)真(zhen)(zhen)空(kong)中加熱(re)到(dao)滲(shen)(shen)碳(tan)(tan)(tan)溫度(du)并保(bao)溫使表面凈(jing)化、活化之后(hou)(hou),通(tong)入(ru)(ru)稀(xi)薄滲(shen)(shen)碳(tan)(tan)(tan)富化氣(qi)(qi)(見(jian)控制氣(qi)(qi)氛熱(re)處理),在(zai)大(da)約(yue)1330Pa(10T0rr)負壓下進(jin)行滲(shen)(shen)入(ru)(ru),然(ran)后(hou)(hou)停氣(qi)(qi)(降(jiang)壓)進(jin)行擴(kuo)散(san)。滲(shen)(shen)碳(tan)(tan)(tan)后(hou)(hou)的(de)精密鋼管淬(cui)火采(cai)用(yong)(yong)一次淬(cui)火法(fa)(fa),即先停電(dian),通(tong)氮(dan)冷(leng)卻(que)工件(jian)至臨界點(dian)A,、以下,使內部(bu)發生相(xiang)變,再停氣(qi)(qi)、開泵(beng),升(sheng)溫到(dao)Ac1,~Accm之間。淬(cui)冷(leng)方法(fa)(fa)可采(cai)用(yong)(yong)氣(qi)(qi)冷(leng)或油冷(leng)。后(hou)(hou)者為(wei)(wei)奧氏體(ti)化后(hou)(hou)移入(ru)(ru)前室(shi),充(chong)氮(dan)至常壓,入(ru)(ru)油。真(zhen)(zhen)空(kong)滲(shen)(shen)碳(tan)(tan)(tan)的(de)溫度(du)一般高(gao)于普通(tong)氣(qi)(qi)體(ti)滲(shen)(shen)碳(tan)(tan)(tan),常采(cai)用(yong)(yong)920~1040℃滲(shen)(shen)入(ru)(ru)和擴(kuo)散(san)可按(an)所示分兩階(jie)段,也可用(yong)(yong)脈沖式(shi)通(tong)氣(qi)(qi)、停氣(qi)(qi),多段式(shi)的(de)滲(shen)(shen)一擴(kuo)相(xiang)間,效果更好。由于溫度(du)高(gao),尤其表面潔凈(jing)、有活性,真(zhen)(zhen)空(kong)滲(shen)(shen)碳(tan)(tan)(tan)層(ceng)形成速度(du)比(bi)普通(tong)氣(qi)(qi)體(ti)、液(ye)體(ti)和固體(ti)滲(shen)(shen)碳(tan)(tan)(tan)快,如要求滲(shen)(shen)層(ceng)為(wei)(wei)1mm時,在(zai)927℃只(zhi)需5h,而1033℃僅(jin)需1h。
精密鋼管(guan)硬度與(yu)變(bian)形
取(qu)兩塊(kuai)(kuai)式樣,一塊(kuai)(kuai)用于研究(jiu)(jiu)不同形變程度對(dui)(dui)硬度的(de)影響(xiang),另一塊(kuai)(kuai)研究(jiu)(jiu)不同溫度對(dui)(dui)性能的(de)影響(xiang)。
冷(leng)(leng)變(bian)(bian)形(xing)(xing)(xing)強(qiang)(qiang)化(hua)在實際生(sheng)產(chan)(chan)中具有(you)重要的(de)(de)(de)意義。首先這(zhe)是一種重要的(de)(de)(de)強(qiang)(qiang)化(hua)材(cai)料的(de)(de)(de)手段,尤其對用熱(re)處理不能強(qiang)(qiang)化(hua)的(de)(de)(de)材(cai)料來(lai)說,顯得更為重要。其次,冷(leng)(leng)變(bian)(bian)形(xing)(xing)(xing)強(qiang)(qiang)化(hua)有(you)利(li)于金屬的(de)(de)(de)變(bian)(bian)形(xing)(xing)(xing)均(jun)勻。因為精密(mi)鋼管的(de)(de)(de)變(bian)(bian)形(xing)(xing)(xing)部分產(chan)(chan)生(sheng)硬(ying)化(hua),將使(shi)變(bian)(bian)形(xing)(xing)(xing)向未變(bian)(bian)形(xing)(xing)(xing)或變(bian)(bian)形(xing)(xing)(xing)較少的(de)(de)(de)部分繼(ji)續發展(zhan)。第三(san),冷(leng)(leng)變(bian)(bian)形(xing)(xing)(xing)強(qiang)(qiang)化(hua)可以提高構件(jian)在使(shi)用過程(cheng)(cheng)中的(de)(de)(de)安全性,構件(jian)一旦超載,產(chan)(chan)生(sheng)塑(su)性變(bian)(bian)形(xing)(xing)(xing),由于強(qiang)(qiang)化(hua)作用,可防(fang)止構件(jian)突然斷(duan)裂(lie)。但是,冷(leng)(leng)變(bian)(bian)形(xing)(xing)(xing)強(qiang)(qiang)化(hua)也給精密(mi)鋼管的(de)(de)(de)繼(ji)續變(bian)(bian)形(xing)(xing)(xing)帶來(lai)困(kun)難,甚至出現(xian)裂(lie)紋。因此(ci),在精密(mi)鋼管變(bian)(bian)形(xing)(xing)(xing)和加工過程(cheng)(cheng)中常進(jin)行"中間退火",以消除它(ta)的(de)(de)(de)不利(li)影響。