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(san)種情況將造成金(jin)屬永久(jiu)損(sun)(sun)傷，使(shi)材料塑(su)性或強(qiang)度降低，即(ji)使(shi)從金(jin)屬中(zhong)除氫損(sun)(sun)傷也不能消除，塑(su)性或強(qiang)度也不能恢復，故稱為(wei)不可(ke)逆氫脆。

2. 第二類氫脆

 氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)的(de)(de)(de)敏感(gan)性(xing)隨應(ying)(ying)變速(su)(su)率(lv)增加(jia)而降低(di)(di)，即(ji)材料在(zai)加(jia)載(zai)前(qian)并不(bu)(bu)存在(zai)裂紋源，加(jia)載(zai)后(hou)在(zai)應(ying)(ying)力(li)(li)(li)(li)(li)和氫(qing)(qing)(qing)的(de)(de)(de)交互(hu)作用(yong)下逐(zhu)漸形(xing)(xing)(xing)(xing)(xing)成裂紋源，最(zui)終(zhong)導(dao)致脆(cui)(cui)(cui)(cui)(cui)性(xing)斷(duan)裂。第(di)二類氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)包括兩種形(xing)(xing)(xing)(xing)(xing)式：一是(shi)應(ying)(ying)力(li)(li)(li)(li)(li)誘發氫(qing)(qing)(qing)化(hua)(hua)(hua)物型氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)。在(zai)能(neng)(neng)夠(gou)形(xing)(xing)(xing)(xing)(xing)成脆(cui)(cui)(cui)(cui)(cui)性(xing)氫(qing)(qing)(qing)化(hua)(hua)(hua)物的(de)(de)(de)金(jin)屬中(zhong)，當氫(qing)(qing)(qing)含量較(jiao)低(di)(di)或(huo)氫(qing)(qing)(qing)在(zai)固(gu)溶體中(zhong)的(de)(de)(de)過飽和度較(jiao)低(di)(di)時(shi)(shi)，尚不(bu)(bu)能(neng)(neng)自發形(xing)(xing)(xing)(xing)(xing)成氫(qing)(qing)(qing)化(hua)(hua)(hua)物；而在(zai)應(ying)(ying)力(li)(li)(li)(li)(li)作用(yong)下，氫(qing)(qing)(qing)會向(xiang)(xiang)應(ying)(ying)力(li)(li)(li)(li)(li)集(ji)中(zhong)處富集(ji)，當氫(qing)(qing)(qing)濃(nong)度超過臨界值時(shi)(shi)就會沉淀出氫(qing)(qing)(qing)化(hua)(hua)(hua)物。這種應(ying)(ying)力(li)(li)(li)(li)(li)誘發的(de)(de)(de)氫(qing)(qing)(qing)化(hua)(hua)(hua)物相變只在(zai)較(jiao)低(di)(di)的(de)(de)(de)應(ying)(ying)變速(su)(su)率(lv)下出現，并由(you)此(ci)導(dao)致脆(cui)(cui)(cui)(cui)(cui)性(xing)斷(duan)裂，一旦出現氫(qing)(qing)(qing)化(hua)(hua)(hua)物，即(ji)使卸載(zai)除(chu)氫(qing)(qing)(qing)，靜止一段時(shi)(shi)間后(hou)再高(gao)速(su)(su)變形(xing)(xing)(xing)(xing)(xing)，塑(su)性(xing)也(ye)不(bu)(bu)能(neng)(neng)恢(hui)復，故也(ye)是(shi)不(bu)(bu)可逆氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)。二是(shi)可逆氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)。是(shi)指含氫(qing)(qing)(qing)金(jin)屬在(zai)高(gao)速(su)(su)變形(xing)(xing)(xing)(xing)(xing)時(shi)(shi)并不(bu)(bu)顯示脆(cui)(cui)(cui)(cui)(cui)性(xing)，而在(zai)緩(huan)慢變形(xing)(xing)(xing)(xing)(xing)時(shi)(shi)由(you)于(yu)氫(qing)(qing)(qing)逐(zhu)漸向(xiang)(xiang)應(ying)(ying)力(li)(li)(li)(li)(li)集(ji)中(zhong)處富集(ji)，在(zai)應(ying)(ying)力(li)(li)(li)(li)(li)與氫(qing)(qing)(qing)交互(hu)作用(yong)下裂紋形(xing)(xing)(xing)(xing)(xing)核、擴展，最(zui)終(zhong)導(dao)致脆(cui)(cui)(cui)(cui)(cui)性(xing)的(de)(de)(de)斷(duan)裂，在(zai)未形(xing)(xing)(xing)(xing)(xing)成裂紋前(qian)去除(chu)載(zai)荷，靜置一段時(shi)(shi)間后(hou)高(gao)速(su)(su)變形(xing)(xing)(xing)(xing)(xing)，材料的(de)(de)(de)塑(su)性(xing)可以得到恢(hui)復，即(ji)應(ying)(ying)力(li)(li)(li)(li)(li)去除(chu)后(hou)脆(cui)(cui)(cui)(cui)(cui)性(xing)消失(shi)，因(yin)此(ci)稱為可逆氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)。由(you)內(nei)氫(qing)(qing)(qing)引起的(de)(de)(de)稱可逆內(nei)氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)，由(you)外氫(qing)(qing)(qing)引起的(de)(de)(de)稱環(huan)境氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)。通常所說的(de)(de)(de)氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)主(zhu)要指可逆氫(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)，是(shi)氫(qing)(qing)(qing)致開裂中(zhong)最(zui)主(zhu)要、最(zui)危(wei)險的(de)(de)(de)破(po)壞形(xing)(xing)(xing)(xing)(xing)式。