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熱處(chu)理淬火后的(de)冷卻速(su)度對于(yu)大厚度鍛件力學性能的(de)影響

文章來源：sjzwx 更新時間：2014-10-29 09:10:32

    大厚度鍛件之所(suo)(suo)以(yi)制造難度(du)(du)(du)(du)(du)大(da)(da)(da)，其主要(yao)原(yuan)因之一就(jiu)(jiu)是淬(cui)(cui)火(huo)時(shi)(shi)(shi)(shi)(shi)(shi)高(gao)溫(wen)(wen)階段在(zai)大(da)(da)(da)厚(hou)度(du)(du)(du)(du)(du)鍛(duan)件的(de)(de)(de)(de)(de)(de)表面所(suo)(suo)形(xing)成的(de)(de)(de)(de)(de)(de)蒸汽膜阻(zu)礙了(le)鍛(duan)件在(zai)厚(hou)度(du)(du)(du)(du)(du)方向上的(de)(de)(de)(de)(de)(de)冷(leng)(leng)(leng)卻速度(du)(du)(du)(du)(du)，尤(you)其是其取(qu)樣(yang)位置處(chu)的(de)(de)(de)(de)(de)(de)冷(leng)(leng)(leng)卻速度(du)(du)(du)(du)(du)，不利(li)于(yu)(yu)大(da)(da)(da)鍛(duan)件獲(huo)取(qu)綜合(he)(he)性(xing)能(neng)(neng)良(liang)好的(de)(de)(de)(de)(de)(de)金相(xiang)組(zu)織(zhi)(zhi)(zhi)(zhi)，即生成下(xia)貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)組(zu)織(zhi)(zhi)(zhi)(zhi)。冷(leng)(leng)(leng)卻曲線。當5八5080.301.2鋼的(de)(de)(de)(de)(de)(de)冷(leng)(leng)(leng)卻速度(du)(du)(du)(du)(du)在(zai)5～11八時(shi)(shi)(shi)(shi)(shi)(shi)，淬(cui)(cui)火(huo)就(jiu)(jiu)可(ke)(ke)以(yi)獲(huo)得綜合(he)(he)性(xing)能(neng)(neng)良(liang)好的(de)(de)(de)(de)(de)(de)下(xia)貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)組(zu)織(zhi)(zhi)(zhi)(zhi)；當冷(leng)(leng)(leng)卻速度(du)(du)(du)(du)(du)小于(yu)(yu)或等(deng)(deng)于(yu)(yu)0.51/3時(shi)(shi)(shi)(shi)(shi)(shi)，將(jiang)形(xing)成鐵素體(ti)(ti)(ti)(ti)(ti)(ti)十上貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)組(zu)織(zhi)(zhi)(zhi)(zhi)的(de)(de)(de)(de)(de)(de)混(hun)合(he)(he)組(zu)織(zhi)(zhi)(zhi)(zhi)。為(wei)(wei)不同等(deng)(deng)溫(wen)(wen)溫(wen)(wen)度(du)(du)(du)(du)(du)下(xia)過(guo)冷(leng)(leng)(leng)奧(ao)(ao)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)等(deng)(deng)溫(wen)(wen)轉(zhuan)變產物(wu)(wu)的(de)(de)(de)(de)(de)(de)掃(sao)描電(dian)鏡照(zhao)片。在(zai)4201等(deng)(deng)溫(wen)(wen)時(shi)(shi)(shi)(shi)(shi)(shi)，過(guo)冷(leng)(leng)(leng)奧(ao)(ao)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)等(deng)(deng)溫(wen)(wen)轉(zhuan)變產物(wu)(wu)為(wei)(wei)細小的(de)(de)(de)(de)(de)(de)下(xia)貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)組(zu)織(zhi)(zhi)(zhi)(zhi)，形(xing)成溫(wen)(wen)度(du)(du)(du)(du)(du)為(wei)(wei)480X：時(shi)(shi)(shi)(shi)(shi)(shi)，過(guo)冷(leng)(leng)(leng)奧(ao)(ao)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)等(deng)(deng)溫(wen)(wen)轉(zhuan)變產物(wu)(wu)仍為(wei)(wei)下(xia)貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)組(zu)織(zhi)(zhi)(zhi)(zhi)，但貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)束(shu)區(qu)尺寸明(ming)顯增(zeng)加，貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)鐵素體(ti)(ti)(ti)(ti)(ti)(ti)寬度(du)(du)(du)(du)(du)加大(da)(da)(da)，貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)內(nei)部(bu)的(de)(de)(de)(de)(de)(de)碳化(hua)物(wu)(wu)顆粒(li)也有所(suo)(suo)粗(cu)化(hua)；進一步(bu)提髙等(deng)(deng)溫(wen)(wen)轉(zhuan)變溫(wen)(wen)度(du)(du)(du)(du)(du)0500X：〉，過(guo)冷(leng)(leng)(leng)奧(ao)(ao)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)等(deng)(deng)溫(wen)(wen)轉(zhuan)變產物(wu)(wu)將(jiang)與低溫(wen)(wen)轉(zhuan)變產物(wu)(wu)出現(xian)明(ming)顯區(qu)別，見圖X：等(deng)(deng)溫(wen)(wen)的(de)(de)(de)(de)(de)(de)組(zu)織(zhi)(zhi)(zhi)(zhi)以(yi)羽毛狀(zhuang)的(de)(de)(de)(de)(de)(de)上貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)為(wei)(wei)主；顯示(shi)在(zai)520X：等(deng)(deng)溫(wen)(wen)時(shi)(shi)(shi)(shi)(shi)(shi)，出現(xian)了(le)上貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)與殘余奧(ao)(ao)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)的(de)(de)(de)(de)(de)(de)混(hun)合(he)(he)組(zu)織(zhi)(zhi)(zhi)(zhi)。由(you)此可(ke)(ke)知(zhi)，等(deng)(deng)溫(wen)(wen)轉(zhuan)變溫(wen)(wen)度(du)(du)(du)(du)(du)越(yue)(yue)髙，過(guo)冷(leng)(leng)(leng)奧(ao)(ao)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)晶粒(li)尺寸越(yue)(yue)大(da)(da)(da)，殘余奧(ao)(ao)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)量(liang)越(yue)(yue)多。在(zai)低于(yu)(yu)480X：等(deng)(deng)溫(wen)(wen)時(shi)(shi)(shi)(shi)(shi)(shi)，基本上可(ke)(ke)以(yi)獲(huo)得百分百的(de)(de)(de)(de)(de)(de)下(xia)貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)組(zu)織(zhi)(zhi)(zhi)(zhi)。大(da)(da)(da)于(yu)(yu)這(zhe)個溫(wen)(wen)度(du)(du)(du)(du)(du)等(deng)(deng)溫(wen)(wen)時(shi)(shi)(shi)(shi)(shi)(shi)，過(guo)冷(leng)(leng)(leng)奧(ao)(ao)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)就(jiu)(jiu)會轉(zhuan)變形(xing)成一定數量(liang)上組(zu)織(zhi)(zhi)(zhi)(zhi)粗(cu)大(da)(da)(da)貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)與殘余奧(ao)(ao)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)的(de)(de)(de)(de)(de)(de)混(hun)合(he)(he)組(zu)織(zhi)(zhi)(zhi)(zhi)。金相(xiang)學(xue)理論可(ke)(ke)知(zhi)：羽毛狀(zhuang)上貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)組(zu)織(zhi)(zhi)(zhi)(zhi)脆性(xing)大(da)(da)(da),綜合(he)(he)力(li)(li)學(xue)性(xing)能(neng)(neng)難以(yi)滿足要(yao)求；而(er)(er)下(xia)貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)組(zu)織(zhi)(zhi)(zhi)(zhi)具有優良(liang)的(de)(de)(de)(de)(de)(de)綜合(he)(he)力(li)(li)學(xue)性(xing)能(neng)(neng)。若鍛(duan)件取(qu)樣(yang)部(bu)位處(chu)的(de)(de)(de)(de)(de)(de)冷(leng)(leng)(leng)卻速度(du)(du)(du)(du)(du)低于(yu)(yu)0.51/3，材料中易出現(xian)鐵素體(ti)(ti)(ti)(ti)(ti)(ti)組(zu)織(zhi)(zhi)(zhi)(zhi)和上貝(bei)氏(shi)(shi)(shi)(shi)(shi)體(ti)(ti)(ti)(ti)(ti)(ti)組(zu)織(zhi)(zhi)(zhi)(zhi)，導(dao)致試樣(yang)的(de)(de)(de)(de)(de)(de)綜合(he)(he)性(xing)能(neng)(neng)下(xia)降，從而(er)(er)導(dao)致力(li)(li)學(xue)性(xing)能(neng)(neng)試驗(yan)結果不合(he)(he)格幾率增(zeng)大(da)(da)(da)。