超深(shen)冷(leng)低溫去應力(li)爐(lu)又(you)稱低溫退火爐(lu),主要用(yong)于消(xiao)除鑄(zhu)件(jian)(jian)、鍛件(jian)(jian)、焊接件(jian)(jian)、冷(leng)沖壓件(jian)(jian)以及(ji)機加工(gong)(gong)(gong)(gong)中的(de)殘余(yu)應力(li)。低溫去應力(li)工(gong)(gong)(gong)(gong)藝(yi)是將(jiang)工(gong)(gong)(gong)(gong)件(jian)(jian)慢慢加熱(re)到去應力(li)工(gong)(gong)(gong)(gong)藝(yi)溫度(du)后,保(bao)溫一(yi)段(duan)時(shi)間后,然后隨爐(lu)冷(leng)卻(que)的(de)熱(re)處(chu)理工(gong)(gong)(gong)(gong)藝(yi)。低溫去應力(li)加熱(re)溫度(du)一(yi)般較低,適用(yong)于毛坯(pi)件(jian)(jian)及(ji)經過切削加工(gong)(gong)(gong)(gong)的(de)零(ling)(ling)件(jian)(jian),可消(xiao)除毛坯(pi)件(jian)(jian)和零(ling)(ling)件(jian)(jian)中的(de)殘余(yu)應力(li),穩(wen)定(ding)工(gong)(gong)(gong)(gong)件(jian)(jian)尺(chi)寸及(ji)形(xing)狀,減少零(ling)(ling)件(jian)(jian)在切削加工(gong)(gong)(gong)(gong)和使用(yong)過程中的(de)形(xing)變和裂紋(wen)傾(qing)向。
冷(leng)形變(bian)后(hou)的(de)(de)(de)金(jin)屬在(zai)低于再結晶溫度加熱(re)(re),以去(qu)除(chu)內(nei)應(ying)(ying)(ying)力(li)(li)(li),但仍保(bao)留冷(leng)作(zuo)硬(ying)化(hua)效果的(de)(de)(de)熱(re)(re)處理,稱為(wei)去(qu)應(ying)(ying)(ying)力(li)(li)(li)退火(huo)(huo),也稱低溫退火(huo)(huo)。 在(zai)去(qu)應(ying)(ying)(ying)力(li)(li)(li)退火(huo)(huo)中(zhong)(zhong)金(jin)屬組織(zhi)及性能的(de)(de)(de)變(bian)化(hua),相當于溫度曲線圖中(zhong)(zhong)的(de)(de)(de)恢復階(jie)段。在(zai)實際生產 中(zhong)(zhong),去(qu)應(ying)(ying)(ying)力(li)(li)(li)退火(huo)(huo)工(gong)藝的(de)(de)(de)應(ying)(ying)(ying)用(yong)比上述定義廣泛得(de)多。熱(re)(re)鍛軋、鑄造、各種(zhong)冷(leng)變(bian)形加工(gong)、切(qie) 削或切(qie)割、焊接、熱(re)(re)處理,甚(shen)至機(ji)器零部件裝配(pei)后(hou),在(zai)不改(gai)變(bian)組織(zhi)狀態,保(bao)留冷(leng)作(zuo)、熱(re)(re)作(zuo)或表面硬(ying)化(hua)的(de)(de)(de)條件下,對鋼材或機(ji)器零部件進行較(jiao)低溫度的(de)(de)(de)加熱(re)(re),以去(qu)除(chu)內(nei)應(ying)(ying)(ying)力(li)(li)(li),減小變(bian)形開裂傾向的(de)(de)(de)工(gong)藝,都可稱為(wei)去(qu)應(ying)(ying)(ying)力(li)(li)(li)退火(huo)(huo)。
超深冷低溫(wen)(wen)(wen)(wen)去(qu)(qu)應力爐(lu)(lu)(lu)(lu)外殼由型鋼和鋼板制(zhi)(zhi)作成(cheng)方形(xing)結構(gou),結構(gou)類(lei)型類(lei)似于(yu)臺(tai)車式退(tui)(tui)火爐(lu)(lu)(lu)(lu),可(ke)以(yi)根據不同的去(qu)(qu)應力退(tui)(tui)火溫(wen)(wen)(wen)(wen)度(du)(du),設計制(zhi)(zhi)造不同使(shi)用溫(wen)(wen)(wen)(wen)度(du)(du)的去(qu)(qu)應力退(tui)(tui)火爐(lu)(lu)(lu)(lu)。該爐(lu)(lu)(lu)(lu)型爐(lu)(lu)(lu)(lu)體(ti)結構(gou)優良、保(bao)溫(wen)(wen)(wen)(wen)層制(zhi)(zhi)造工藝(yi)(yi)嚴格,采用高(gao)標(biao)準發(fa)熱(re)元件(jian),并(bing)采用全自(zi)動(dong)微電(dian)腦工藝(yi)(yi)自(zi)動(dong)控溫(wen)(wen)(wen)(wen)系統,使(shi)爐(lu)(lu)(lu)(lu)內(nei)溫(wen)(wen)(wen)(wen)度(du)(du)均溫(wen)(wen)(wen)(wen)。去(qu)(qu)應力退(tui)(tui)火工藝(yi)(yi)自(zi)由編程,并(bing)自(zi)動(dong)控制(zhi)(zhi)升(sheng)溫(wen)(wen)(wen)(wen)速度(du)(du)、保(bao)溫(wen)(wen)(wen)(wen)溫(wen)(wen)(wen)(wen)度(du)(du)及保(bao)溫(wen)(wen)(wen)(wen)時間(jian),控溫(wen)(wen)(wen)(wen)精度(du)(du)達到±1℃。
超深(shen)冷低(di)溫去應(ying)力爐熱處理主要(yao)有(you):退火(huo)(huo)(huo)、正火(huo)(huo)(huo)、淬(cui)火(huo)(huo)(huo)和(he)回火(huo)(huo)(huo)四種常用方法。
退火目的:
1、降低硬度(du)
2、提高韌性
3、消除殘余應力
4、獲得需要的機械性(xing)能(neng)
5、穩定(ding)尺寸
6、便于加工
7、改善切削加工(gong)性(xing)
8、減少氧化脫碳現象
9、防止變形(xing)
10、節約能(neng)源退(tui)火分類
11、或非退火或非退火的目(mu)的是(shi):
(1)降低材料硬度和脆性
(2)細化(hua)晶粒
(3)消(xiao)除(chu)顯微組織(zhi)的缺陷(xian)
(4)調整力學性(xing)能(neng)
(5)為后續的時效硬(ying)化作(zuo)好準備(bei)
不全退火的目(mu)的是:
(1)通(tong)過適當控(kong)制加熱溫度來滿足某些(xie)特殊要(yao)求
(2)通(tong)過選(xuan)擇適當的(de)保溫時間以達到所(suo)要(yao)求(qiu)的(de)強度
(3)為(wei)了保證一定的塑(su)性和韌性而不致(zhi)使(shi)材料過分軟化
(4)避免在較低的溫(wen)度下發(fa)生馬(ma)氏體轉變
(5)避免(mian)在較高的溫(wen)度下發生相變
(6)防(fang)止出現白點
(7)防止過(guo)熱
(8)保持(chi)足夠的強度(du)
(9)使金相組織(zhi)和力學性能符(fu)合(he)要求。
正火的目的:
1)改善含碳(tan)量較低的鋼(gang)材的切(qie)削性能。
2)中碳結構鋼要(yao)求(qiu)不高(gao)時(shi),可代替(ti)調質作為熱(re)處理,起到簡(jian)化工藝的目的。
3)消除過共(gong)析鋼的網狀滲碳物。
4)消除缺陷(xian)、細化晶粒、改善組(zu)織、為熱處理做準備。