電解液的加熱是以直流電為電源在電解液中進行的，適用于表面加熱淬火的電解液很多，一般采用質量分數為8％～10％的Na2CO3水溶液。
電(dian)(dian)解(jie)(jie)(jie)液表(biao)面(mian)淬(cui)火(huo)(huo)(huo)原理是將(jiang)工(gong)(gong)件(jian)(jian)(jian)置于(yu)電(dian)(dian)解(jie)(jie)(jie)液中（局部或全部）作為(wei)陰(yin)極，金屬電(dian)(dian)解(jie)(jie)(jie)槽作為(wei)陽極。電(dian)(dian)路接(jie)通(tong)后，電(dian)(dian)解(jie)(jie)(jie)液發生(sheng)電(dian)(dian)離，在陽極上(shang)放出(chu)氧，在陰(yin)極上(shang)放出(chu)氫。氫圍繞(rao)工(gong)(gong)件(jian)(jian)(jian)形(xing)成氣膜(mo)，產生(sheng)很大(da)的(de)電(dian)(dian)阻，通(tong)過的(de)電(dian)(dian)流轉化為(wei)熱(re)能將(jiang)工(gong)(gong)件(jian)(jian)(jian)表(biao)面(mian)迅速加(jia)熱(re)到臨(lin)界點以上(shang)溫度。電(dian)(dian)路斷開氣膜(mo)消(xiao)失，加(jia)熱(re)的(de)工(gong)(gong)件(jian)(jian)(jian)在電(dian)(dian)解(jie)(jie)(jie)液中即實現淬(cui)火(huo)(huo)(huo)冷卻(que)。此方法所用設備簡(jian)(jian)單，淬(cui)火(huo)(huo)(huo)變形(xing)小，適用于(yu)形(xing)狀簡(jian)(jian)單、小工(gong)(gong)件(jian)(jian)(jian)的(de)批量生(sheng)產。
電(dian)解(jie)液溫度(du)不(bu)能超(chao)過(guo)60℃。溫度(du)過(guo)高(gao)，氫氣(qi)膜(mo)不(bu)穩定，影(ying)響(xiang)加(jia)熱(re)(re)過(guo)程，還會(hui)加(jia)速溶液的蒸發。常用(yong)電(dian)壓為160～180V，最高(gao)不(bu)超(chao)過(guo)260V，電(dian)流密(mi)度(du)的范圍是4～10A／c㎡，通常可(ke)選(xuan)用(yong)6A／c㎡。電(dian)流密(mi)度(du)過(guo)大時，加(jia)熱(re)(re)速度(du)快，淬(cui)硬(ying)層薄。在(zai)(zai)加(jia)熱(re)(re)過(guo)程中，應將工(gong)件(jian)的位置加(jia)以固定，否則會(hui)造成電(dian)流密(mi)度(du)的變化(hua)，使淬(cui)硬(ying)層質量惡化(hua)。加(jia)熱(re)(re)時間可(ke)通過(guo)試驗確(que)定。工(gong)件(jian)在(zai)(zai)電(dian)解(jie)液中可(ke)采用(yong)端(duan)部自由加(jia)熱(re)(re)、端(duan)部絕緣(yuan)加(jia)熱(re)(re)、回轉(zhuan)加(jia)熱(re)(re)和連續加(jia)熱(re)(re)等方式(shi)。
