按照氫脆敏感性與應變速率的關系，可以將氫致開裂分為兩大類。

1. 第(di)一類氫脆

 氫脆的敏感性隨應變速率的增加而增加，即材料加載前內部已存在某種裂紋源，加載后在應力作用下加快了裂紋的形成與擴展。第一類氫脆包括三種形式：①. 氫腐蝕，由于氫在高溫高壓下與金屬中第二相（夾雜物和合金添加物）發生化學反應，生成高壓氣體（如CH₄、SiH₄)引起材料脫碳、內裂紋和鼓泡的現象；②. 氫鼓泡，過飽和的氫原子在缺陷位置（如夾雜）析出，形成氫分子，在局部造成很高的氫壓，引起表面鼓泡或內部裂紋的現象；③. 氫化物型氫脆，氫與IVB和VB族金屬有較大的親和力，氫含量較高時容易產生脆性的氫化物相，并在隨后受力時成為裂紋源，引起脆斷。

 上述三種(zhong)情(qing)況將(jiang)造成(cheng)金屬(shu)(shu)永(yong)久損傷(shang)，使材料塑性(xing)或(huo)強度(du)降低，即使從金屬(shu)(shu)中除(chu)氫損傷(shang)也不能消除(chu)，塑性(xing)或(huo)強度(du)也不能恢復，故稱為不可逆氫脆。

2. 第(di)二類(lei)氫脆

 氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)的(de)(de)敏感性(xing)(xing)隨(sui)應(ying)變速(su)率增(zeng)加(jia)而降(jiang)低(di)，即(ji)材料在(zai)(zai)加(jia)載前并不存在(zai)(zai)裂紋(wen)源，加(jia)載后(hou)在(zai)(zai)應(ying)力和氫(qing)(qing)(qing)的(de)(de)交(jiao)互(hu)作用下(xia)逐(zhu)漸形(xing)(xing)(xing)成(cheng)裂紋(wen)源，最(zui)終導致(zhi)脆(cui)(cui)(cui)(cui)性(xing)(xing)斷(duan)裂。第(di)二類(lei)氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)包括兩種(zhong)形(xing)(xing)(xing)式：一是(shi)(shi)(shi)應(ying)力誘(you)發氫(qing)(qing)(qing)化(hua)物(wu)(wu)型氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。在(zai)(zai)能夠形(xing)(xing)(xing)成(cheng)脆(cui)(cui)(cui)(cui)性(xing)(xing)氫(qing)(qing)(qing)化(hua)物(wu)(wu)的(de)(de)金屬中(zhong)，當氫(qing)(qing)(qing)含量(liang)較(jiao)(jiao)低(di)或氫(qing)(qing)(qing)在(zai)(zai)固溶體(ti)中(zhong)的(de)(de)過(guo)飽和度較(jiao)(jiao)低(di)時(shi)，尚不能自發形(xing)(xing)(xing)成(cheng)氫(qing)(qing)(qing)化(hua)物(wu)(wu)；而在(zai)(zai)應(ying)力作用下(xia)，氫(qing)(qing)(qing)會向應(ying)力集(ji)中(zhong)處(chu)富(fu)(fu)集(ji)，當氫(qing)(qing)(qing)濃度超(chao)過(guo)臨(lin)界(jie)值時(shi)就會沉(chen)淀出氫(qing)(qing)(qing)化(hua)物(wu)(wu)。這種(zhong)應(ying)力誘(you)發的(de)(de)氫(qing)(qing)(qing)化(hua)物(wu)(wu)相變只在(zai)(zai)較(jiao)(jiao)低(di)的(de)(de)應(ying)變速(su)率下(xia)出現(xian)，并由(you)(you)此(ci)(ci)導致(zhi)脆(cui)(cui)(cui)(cui)性(xing)(xing)斷(duan)裂，一旦出現(xian)氫(qing)(qing)(qing)化(hua)物(wu)(wu)，即(ji)使卸載除(chu)氫(qing)(qing)(qing)，靜(jing)(jing)止一段時(shi)間(jian)后(hou)再高(gao)速(su)變形(xing)(xing)(xing)，塑(su)性(xing)(xing)也不能恢復，故也是(shi)(shi)(shi)不可逆氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。二是(shi)(shi)(shi)可逆氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。是(shi)(shi)(shi)指(zhi)含氫(qing)(qing)(qing)金屬在(zai)(zai)高(gao)速(su)變形(xing)(xing)(xing)時(shi)并不顯示脆(cui)(cui)(cui)(cui)性(xing)(xing)，而在(zai)(zai)緩慢變形(xing)(xing)(xing)時(shi)由(you)(you)于氫(qing)(qing)(qing)逐(zhu)漸向應(ying)力集(ji)中(zhong)處(chu)富(fu)(fu)集(ji)，在(zai)(zai)應(ying)力與氫(qing)(qing)(qing)交(jiao)互(hu)作用下(xia)裂紋(wen)形(xing)(xing)(xing)核、擴展，最(zui)終導致(zhi)脆(cui)(cui)(cui)(cui)性(xing)(xing)的(de)(de)斷(duan)裂，在(zai)(zai)未形(xing)(xing)(xing)成(cheng)裂紋(wen)前去除(chu)載荷，靜(jing)(jing)置一段時(shi)間(jian)后(hou)高(gao)速(su)變形(xing)(xing)(xing)，材料的(de)(de)塑(su)性(xing)(xing)可以得到恢復，即(ji)應(ying)力去除(chu)后(hou)脆(cui)(cui)(cui)(cui)性(xing)(xing)消失，因此(ci)(ci)稱(cheng)為可逆氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。由(you)(you)內(nei)氫(qing)(qing)(qing)引(yin)起的(de)(de)稱(cheng)可逆內(nei)氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)，由(you)(you)外氫(qing)(qing)(qing)引(yin)起的(de)(de)稱(cheng)環(huan)境氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。通(tong)常所(suo)說的(de)(de)氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)主要指(zhi)可逆氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)，是(shi)(shi)(shi)氫(qing)(qing)(qing)致(zhi)開裂中(zhong)最(zui)主要、最(zui)危險的(de)(de)破壞形(xing)(xing)(xing)式。