熱鍛壓指在金屬再結晶溫度以上進行的鍛壓。因為提高溫度能改善金屬的塑性。

是在金(jin)屬(shu)再結晶(jing)溫度(du)(du)(du)以上進行的(de)鍛壓(ya)(ya)。提高(gao)溫度(du)(du)(du)能(neng)改善(shan)金(jin)屬(shu)的(de)塑性(xing)，有利(li)于提高(gao)工(gong)(gong)件的(de)內在質量，使之不(bu)易開裂(lie)。高(gao)溫度(du)(du)(du)還能(neng)減小金(jin)屬(shu)的(de)變形(xing)抗力(li)，降低所需鍛壓(ya)(ya)機械的(de)噸(dun)位。但熱(re)鍛壓(ya)(ya)工(gong)(gong)序多，工(gong)(gong)件精度(du)(du)(du)差，表面不(bu)光潔，鍛件容易產生氧化、脫碳和燒損。當(dang)加工(gong)(gong)工(gong)(gong)件大(da)、厚(hou)，材料強度(du)(du)(du)高(gao)、塑性(xing)低時(shi)（如特厚(hou)板的(de)滾彎、高(gao)碳鋼棒的(de)拔長(chang)等），都采用熱(re)鍛壓(ya)(ya)。

特點：

提高(gao)(gao)溫(wen)(wen)(wen)度(du)(du)(du)(du)能(neng)改(gai)善金(jin)(jin)屬(shu)(shu)的(de)塑性(xing)(xing)，使(shi)之不(bu)易開裂。高(gao)(gao)溫(wen)(wen)(wen)度(du)(du)(du)(du)還能(neng)減小金(jin)(jin)屬(shu)(shu)的(de)變形抗力(li)，降低(di)所需(xu)鍛(duan)(duan)(duan)壓(ya)(ya)(ya)機械(xie)的(de)噸位。高(gao)(gao)溫(wen)(wen)(wen)變形有(you)利于提高(gao)(gao)工(gong)件的(de)內在質量(liang)。但(dan)熱(re)鍛(duan)(duan)(duan)壓(ya)(ya)(ya)工(gong)序多(duo)，工(gong)件精度(du)(du)(du)(du)差，表面不(bu)光(guang)潔，鍛(duan)(duan)(duan)件容易產生(sheng)氧(yang)(yang)化、脫碳和(he)燒損。當金(jin)(jin)屬(shu)(shu)（如(ru)鉛、錫、鋅、銅、鋁等）有(you)足夠的(de)塑性(xing)(xing)和(he)變形量(liang)不(bu)大(da)（如(ru)在大(da)多(duo)數沖壓(ya)(ya)(ya)加(jia)(jia)工(gong)中）時，或變形總量(liang)大(da)而(er)(er)所用(yong)的(de)鍛(duan)(duan)(duan)壓(ya)(ya)(ya)工(gong)藝（如(ru)擠壓(ya)(ya)(ya)、徑向鍛(duan)(duan)(duan)造等）有(you)利于金(jin)(jin)屬(shu)(shu)的(de)塑性(xing)(xing)變形時，常不(bu)采用(yong)熱(re)鍛(duan)(duan)(duan)壓(ya)(ya)(ya)，而(er)(er)改(gai)用(yong)冷鍛(duan)(duan)(duan)壓(ya)(ya)(ya)。為使(shi)一次加(jia)(jia)熱(re)完成盡(jin)(jin)量(liang)多(duo)的(de)鍛(duan)(duan)(duan)壓(ya)(ya)(ya)工(gong)作量(liang)，熱(re)鍛(duan)(duan)(duan)壓(ya)(ya)(ya)的(de)始鍛(duan)(duan)(duan)溫(wen)(wen)(wen)度(du)(du)(du)(du)與終鍛(duan)(duan)(duan)溫(wen)(wen)(wen)度(du)(du)(du)(du)間(jian)(jian)的(de)溫(wen)(wen)(wen)度(du)(du)(du)(du)區間(jian)(jian)應盡(jin)(jin)可(ke)能(neng)大(da)。但(dan)始鍛(duan)(duan)(duan)溫(wen)(wen)(wen)度(du)(du)(du)(du)過高(gao)(gao)會引(yin)起金(jin)(jin)屬(shu)(shu)晶粒生(sheng)長過大(da)而(er)(er)形成過熱(re)現象，會降低(di)鍛(duan)(duan)(duan)壓(ya)(ya)(ya)件質量(liang)。溫(wen)(wen)(wen)度(du)(du)(du)(du)接近金(jin)(jin)屬(shu)(shu)熔(rong)點時則會發生(sheng)晶間(jian)(jian)低(di)熔(rong)點物質熔(rong)化和(he)晶間(jian)(jian)氧(yang)(yang)化，形成過燒。過燒的(de)坯料在鍛(duan)(duan)(duan)壓(ya)(ya)(ya)時往往碎裂。一般采用(yong)的(de)熱(re)鍛(duan)(duan)(duan)壓(ya)(ya)(ya)溫(wen)(wen)(wen)度(du)(du)(du)(du)為：碳素鋼800～1250℃；合金(jin)(jin)結構鋼850～1150℃；高(gao)(gao)速(su)鋼900～1100℃；常用(yong)的(de)鋁合金(jin)(jin) 380～500℃；鈦合金(jin)(jin)850～1000℃；黃銅700～900℃。