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鍛造比對力學性(xing)能的影響

文章來源：sjzwx 更(geng)新時間：2015-01-07 09:32:19

    金屬的力(li)(li)學性(xing)(xing)(xing)能決定于(yu)它的組(zu)織狀態。鋼(gang)錠經(jing)過適(shi)當鍛造(zao)比值(zhi)(zhi)的鍛造(zao)變(bian)(bian)形可獲得致密的鍛造(zao)組(zu)織，晶粒細化，縱向(xiang)(xiang)和橫向(xiang)(xiang)力(li)(li)學性(xing)(xing)(xing)能均(jun)(jun)有顯著提高(gao)(gao)。生(sheng)產實踐檢驗(yan)結果(guo)(guo)表明：鋼(gang)錠經(jing)拔長變(bian)(bian)形，鍛造(zao)比為(wei)(wei)2-3時，強度(du)指(zhi)(zhi)標已接(jie)近最大(da)(da)值(zhi)(zhi)，縱向(xiang)(xiang)(流線方向(xiang)(xiang))的塑(su)陛(bi)指(zhi)(zhi)標、韌(ren)生(sheng)指(zhi)(zhi)標達(da)(da)到(dao)最大(da)(da)值(zhi)(zhi)；鍛造(zao)比繼續增(zeng)大(da)(da)時，強度(du)指(zhi)(zhi)標變(bian)(bian)化不大(da)(da)，且方向(xiang)(xiang)性(xing)(xing)(xing)不明顯，塑(su)性(xing)(xing)(xing)指(zhi)(zhi)標、韌(ren)性(xing)(xing)(xing)指(zhi)(zhi)標方向(xiang)(xiang)性(xing)(xing)(xing)明顯，橫向(xiang)(xiang)(切向(xiang)(xiang)、徑向(xiang)(xiang))的塑(su)性(xing)(xing)(xing)指(zhi)(zhi)標、韌(ren)性(xing)(xing)(xing)指(zhi)(zhi)標開始下降。冶金純(chun)凈度(du)較差的鋼(gang)異(yi)向(xiang)(xiang)性(xing)(xing)(xing)系數(shu)下降較劇(ju)烈。此外(wai)，適(shi)當增(zeng)大(da)(da)鍛造(zao)比，也是提高(gao)(gao)鍛件(jian)(jian)疲(pi)勞(lao)(lao)極(ji)限(xian)重要(yao)途徑之一。承受重復(fu)或(huo)交變(bian)(bian)載荷的零件(jian)(jian)，如果(guo)(guo)突然發(fa)生(sheng)疲(pi)勞(lao)(lao)損壞，后(hou)果(guo)(guo)極(ji)為(wei)(wei)嚴重。發(fa)生(sheng)疲(pi)勞(lao)(lao)破(po)壞的疲(pi)勞(lao)(lao)源多在零件(jian)(jian)的應(ying)力(li)(li)集中(zhong)處及零件(jian)(jian)內部(bu)缺陷處。鋼(gang)錠通(tong)過鍛造(zao)，提高(gao)(gao)了(le)(le)鋼(gang)料的致密陛(bi)和均(jun)(jun)勻性(xing)(xing)(xing)，宏觀及微觀缺陷得到(dao)改善和消除，減少了(le)(le)應(ying)力(li)(li)集中(zhong)，從而使鍛件(jian)(jian)的抗(kang)疲(pi)勞(lao)(lao)生(sheng)能提高(gao)(gao)。隨著鍛造(zao)比增(zeng)大(da)(da)，鍛件(jian)(jian)疲(pi)勞(lao)(lao)極(ji)限(xian)得到(dao)提高(gao)(gao)，當鍛造(zao)比達(da)(da)到(dao)一定數(shu)值(zhi)(zhi)后(hou)，疲(pi)勞(lao)(lao)極(ji)限(xian)保持同(tong)一水平，不再提高(gao)(gao)。