真空熔煉爐在真空條件下運用電弧來加熱和熔煉金屬的熔煉方法。這種熔煉方法所運用的電極有自耗電極和非自耗電極兩種。自耗電極是由被熔煉資料(即爐料)制成，在熔煉過程中它逐漸耗費;而非自耗電極系運用鎢等高熔點資料制成，在爐料熔煉過程中它基本上不耗費。采用自耗電極的真空電弧爐稱自耗電極電弧爐，簡稱自耗爐;采用非自耗電極的真空電弧爐稱非自耗電極電弧爐，簡稱非自耗爐。非自耗電極熔煉已較少運用，而自耗電極熔煉很多應用于出產實踐中，成為二次重熔的主要手段之一。

真(zhen)(zhen)空(kong)(kong)電(dian)弧(hu)(hu)熔(rong)(rong)(rong)(rong)(rong)煉(lian)的(de)坩堝一般(ban)用銅(tong)制成(cheng)，外(wai)面用水(shui)冷卻，稱為水(shui)冷銅(tong)結晶(jing)(jing)(jing)器。真(zhen)(zhen)空(kong)(kong)熔(rong)(rong)(rong)(rong)(rong)煉(lian)爐熔(rong)(rong)(rong)(rong)(rong)煉(lian)時，可(ke)以將自耗(hao)電(dian)極(ji)(被(bei)熔(rong)(rong)(rong)(rong)(rong)煉(lian)資料(liao))接負極(ji)，水(shui)冷銅(tong)結晶(jing)(jing)(jing)器接正極(ji)，通電(dian)后兩(liang)極(ji)間產(chan)(chan)生弧(hu)(hu)光放(fang)電(dian)，將電(dian)能轉(zhuan)變成(cheng)熱能，產(chan)(chan)生高溫使資料(liao)熔(rong)(rong)(rong)(rong)(rong)化。熔(rong)(rong)(rong)(rong)(rong)煉(lian)過程中(zhong)液態(tai)金(jin)(jin)(jin)屬(shu)熔(rong)(rong)(rong)(rong)(rong)滴經過高溫弧(hu)(hu)區后落入金(jin)(jin)(jin)屬(shu)熔(rong)(rong)(rong)(rong)(rong)池，并在(zai)水(shui)冷銅(tong)結晶(jing)(jing)(jing)器內凝固(gu)成(cheng)錠。經過金(jin)(jin)(jin)屬(shu)液與氣相(xiang)間以及熔(rong)(rong)(rong)(rong)(rong)池內發作的(de)一系列物理化學反應，達到(dao)提(ti)高金(jin)(jin)(jin)屬(shu)的(de)純(chun)凈度(du)，改進(jin)其結晶(jing)(jing)(jing)組織和(he)性能的(de)意(yi)圖。真(zhen)(zhen)空(kong)(kong)電(dian)弧(hu)(hu)熔(rong)(rong)(rong)(rong)(rong)煉(lian)不受大(da)氣、耐火(huo)資料(liao)和(he)鑄模(mo)等的(de)沾污(wu);可(ke)以去除鋼及合(he)(he)金(jin)(jin)(jin)中(zhong)的(de)氣體(ti)和(he)有害(hai)金(jin)(jin)(jin)屬(shu)雜(za)質;熔(rong)(rong)(rong)(rong)(rong)煉(lian)中(zhong)夾雜(za)物也可(ke)上浮去除一部分，并可(ke)改進(jin)夾雜(za)物在(zai)合(he)(he)金(jin)(jin)(jin)中(zhong)的(de)散布及形態(tai);水(shui)冷銅(tong)結晶(jing)(jing)(jing)器中(zhong)的(de)鋼錠鑄態(tai)組織比一般(ban)鑄錠為好。但真(zhen)(zhen)空(kong)(kong)電(dian)弧(hu)(hu)熔(rong)(rong)(rong)(rong)(rong)煉(lian)需預制電(dian)極(ji)，且鋼錠外(wai)表較差。真(zhen)(zhen)空(kong)(kong)電(dian)弧(hu)(hu)熔(rong)(rong)(rong)(rong)(rong)煉(lian)可(ke)用來熔(rong)(rong)(rong)(rong)(rong)煉(lian)鈦、鋯、鎢、鉬等生動金(jin)(jin)(jin)屬(shu)、難熔(rong)(rong)(rong)(rong)(rong)金(jin)(jin)(jin)屬(shu)以及它們的(de)合(he)(he)金(jin)(jin)(jin)，也可(ke)用來熔(rong)(rong)(rong)(rong)(rong)煉(lian)高溫合(he)(he)金(jin)(jin)(jin)及有特(te)殊用途的(de)鋼和(he)合(he)(he)金(jin)(jin)(jin)。