耐磨板的高溫塑性變形特征

  耐(nai)磨(mo)(mo)板(ban)是一種典(dian)型的優(you)質低合金(jin)高強度耐(nai)磨(mo)(mo)鋼,是制造破碎機、刮板(ban)機、盾(dun)構機等耐(nai)磨(mo)(mo)損機械的關(guan)鍵材料(liao)。關(guan)于(yu)耐(nai)磨(mo)(mo)板(ban)的研(yan)究(jiu)已有大量文獻報(bao)(bao)道,這些(xie)研(yan)究(jiu)主要集(ji)中在組織相變、疲勞斷裂性能以及鋼中氫脆等方面,但關(guan)于(yu)其(qi)熱(re)變形行(xing)為(wei)(wei)(wei)還鮮(xian)有報(bao)(bao)道。為(wei)(wei)(wei)此,科技(ji)人員采(cai)用(yong)熱(re)模擬(ni)試驗機對(dui)耐(nai)磨(mo)(mo)板(ban)進(jin)行(xing)了(le)高溫軸向單道次(ci)壓縮變形試驗,系統地(di)研(yan)究(jiu)其(qi)熱(re)變形行(xing)為(wei)(wei)(wei),并對(dui)耐(nai)磨(mo)(mo)板(ban)變形后的顯微組織進(jin)行(xing)了(le)分析,為(wei)(wei)(wei)其(qi)熱(re)加(jia)工工藝的制定和(he)優(you)化提供技(ji)術指(zhi)導和(he)理論(lun)依據(ju)。

  試驗用JFE-C400耐磨板化(hua)學成分(fen)(質量分(fen)數/%)為(wei)0.41C,0.78Mn,0.25Si,0.0006P,0.001S,0.85Cr,1.80Ni,0.25Mo,0.0006O,0.0010N。從(cong)耐磨(mo)板上切取(qu)并加工成Φ8mm×15mm的(de)(de)圓(yuan)柱形(xing)(xing)(xing)壓(ya)(ya)縮(suo)試(shi)(shi)(shi)樣(yang),然(ran)后(hou)(hou)在Gleeble-3800型熱模擬試(shi)(shi)(shi)驗機(ji)上進行高(gao)溫(wen)(wen)(wen)(wen)軸向單道次壓(ya)(ya)縮(suo)試(shi)(shi)(shi)驗。試(shi)(shi)(shi)樣(yang)先(xian)以(yi)10K·s-1的(de)(de)加熱速(su)(su)(su)率加熱到1423K,保(bao)(bao)(bao)溫(wen)(wen)(wen)(wen)5min,然(ran)后(hou)(hou)以(yi)10K·s-1的(de)(de)冷(leng)卻速(su)(su)(su)度(du)冷(leng)卻到不(bu)同的(de)(de)變(bian)(bian)形(xing)(xing)(xing)溫(wen)(wen)(wen)(wen)度(du)(1123,1223,1323,1423K),保(bao)(bao)(bao)溫(wen)(wen)(wen)(wen)5s后(hou)(hou)進行壓(ya)(ya)縮(suo)變(bian)(bian)形(xing)(xing)(xing);其應(ying)變(bian)(bian)速(su)(su)(su)率分(fen)別為(wei)0.01、0.1、1、10s-1,最(zui)大真應(ying)變(bian)(bian)為(wei)0.9,變(bian)(bian)形(xing)(xing)(xing)后(hou)(hou)立刻(ke)噴水冷(leng)卻,以(yi)便(bian)保(bao)(bao)(bao)留高(gao)溫(wen)(wen)(wen)(wen)變(bian)(bian)形(xing)(xing)(xing)后(hou)(hou)的(de)(de)晶(jing)界(jie)。用(yong)線切割(ge)機(ji)把熱壓(ya)(ya)縮(suo)試(shi)(shi)(shi)樣(yang)沿壓(ya)(ya)縮(suo)方向從(cong)中間剖開,磨(mo)平、拋(pao)光(guang)后(hou)(hou),使用(yong)飽(bao)和(he)苦味酸(suan)+少量海(hai)鷗洗(xi)劑混合溶液來腐蝕,顯示奧氏(shi)體晶(jing)界(jie),用(yong)LEICA MEF4M型光(guang)學顯微鏡觀察(cha)其顯微組織。結果表明(ming):

  (1)該耐磨板的流變應力和峰值應變隨著變形溫度的升高和應變速率的降低而減少;
  (2)在真應變為0.9,應變速率為0.01~10s-1的條件下,隨著應變速率的提高,其發生完全動態再結晶的溫度也逐漸升高;
  (3)當應變速率為10s-1,變形溫度高于1323K時,該耐磨板才會發生完全動態再結晶;
  (4)計算得(de)到耐磨板的熱變形激(ji)活能為333.726kJ·mol-1,并建立了該鋼動態(tai)再結(jie)晶條件下峰值應變與Zener-Hollomon因子(zi)的定量關系以及(ji)高溫塑性變形本構(gou)方程(cheng)。