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)(dian)(dian)(dian)解(jie)液(ye)(ye)表面(mian)淬火(huo)原(yuan)理是將工(gong)(gong)件(jian)(jian)置于電(dian)(dian)(dian)(dian)(dian)解(jie)液(ye)(ye)中（局部或全部）作(zuo)(zuo)為陰極(ji)，金屬電(dian)(dian)(dian)(dian)(dian)解(jie)槽作(zuo)(zuo)為陽極(ji)。電(dian)(dian)(dian)(dian)(dian)路(lu)接(jie)通后，電(dian)(dian)(dian)(dian)(dian)解(jie)液(ye)(ye)發生電(dian)(dian)(dian)(dian)(dian)離(li)，在陽極(ji)上放(fang)出氧，在陰極(ji)上放(fang)出氫。氫圍繞(rao)工(gong)(gong)件(jian)(jian)形(xing)成氣膜(mo)，產(chan)生很(hen)大的(de)(de)電(dian)(dian)(dian)(dian)(dian)阻，通過的(de)(de)電(dian)(dian)(dian)(dian)(dian)流轉化為熱(re)能將工(gong)(gong)件(jian)(jian)表面(mian)迅(xun)速(su)加熱(re)到臨界點以上溫度。電(dian)(dian)(dian)(dian)(dian)路(lu)斷開氣膜(mo)消失，加熱(re)的(de)(de)工(gong)(gong)件(jian)(jian)在電(dian)(dian)(dian)(dian)(dian)解(jie)液(ye)(ye)中即實現淬火(huo)冷(leng)卻。此方法所用(yong)設備簡(jian)單(dan)，淬火(huo)變形(xing)小，適用(yong)于形(xing)狀簡(jian)單(dan)、小工(gong)(gong)件(jian)(jian)的(de)(de)批量(liang)生產(chan)。
電解(jie)液溫度(du)(du)(du)(du)不(bu)能超過60℃。溫度(du)(du)(du)(du)過高，氫(qing)氣(qi)膜不(bu)穩(wen)定，影響加熱(re)(re)過程(cheng)，還會(hui)加速溶(rong)液的(de)蒸發。常用(yong)電壓為160～180V，最(zui)高不(bu)超過260V，電流密(mi)(mi)度(du)(du)(du)(du)的(de)范圍是4～10A／c㎡，通常可(ke)(ke)選(xuan)用(yong)6A／c㎡。電流密(mi)(mi)度(du)(du)(du)(du)過大時，加熱(re)(re)速度(du)(du)(du)(du)快，淬(cui)(cui)硬(ying)層薄(bo)。在加熱(re)(re)過程(cheng)中(zhong)，應(ying)將工件的(de)位置加以固(gu)定，否則會(hui)造(zao)成(cheng)電流密(mi)(mi)度(du)(du)(du)(du)的(de)變化(hua)，使(shi)淬(cui)(cui)硬(ying)層質量惡化(hua)。加熱(re)(re)時間(jian)可(ke)(ke)通過試(shi)驗確定。工件在電解(jie)液中(zhong)可(ke)(ke)采用(yong)端部(bu)自由加熱(re)(re)、端部(bu)絕(jue)緣(yuan)加熱(re)(re)、回(hui)轉加熱(re)(re)和(he)連續加熱(re)(re)等方式(shi)。
