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)種情況將造成金屬永久損(sun)傷(shang)，使(shi)材(cai)料(liao)塑性(xing)或強度降(jiang)低(di)，即使(shi)從金屬中除(chu)氫(qing)損(sun)傷(shang)也(ye)(ye)不(bu)能(neng)消(xiao)除(chu)，塑性(xing)或強度也(ye)(ye)不(bu)能(neng)恢(hui)復，故稱為不(bu)可逆氫(qing)脆。

2. 第二類氫脆

 氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)的敏(min)感性(xing)隨應(ying)變速率增加(jia)而(er)降低，即材料(liao)在(zai)加(jia)載前并(bing)不存(cun)在(zai)裂(lie)紋(wen)源，加(jia)載后在(zai)應(ying)力(li)和氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)的交互(hu)作用下逐(zhu)(zhu)漸形(xing)(xing)(xing)成(cheng)裂(lie)紋(wen)源，最終導(dao)(dao)致脆(cui)(cui)(cui)(cui)性(xing)斷裂(lie)。第二(er)類氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)包括兩種形(xing)(xing)(xing)式：一(yi)是(shi)應(ying)力(li)誘(you)發氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)化物型(xing)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。在(zai)能(neng)夠形(xing)(xing)(xing)成(cheng)脆(cui)(cui)(cui)(cui)性(xing)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)化物的金屬中(zhong)(zhong)，當氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)含量(liang)較低或氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)在(zai)固溶體(ti)中(zhong)(zhong)的過飽和度較低時(shi)(shi)，尚不能(neng)自(zi)發形(xing)(xing)(xing)成(cheng)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)化物；而(er)在(zai)應(ying)力(li)作用下，氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)會(hui)(hui)向應(ying)力(li)集(ji)中(zhong)(zhong)處富(fu)集(ji)，當氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)濃度超(chao)過臨界值時(shi)(shi)就(jiu)會(hui)(hui)沉淀出氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)化物。這種應(ying)力(li)誘(you)發的氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)化物相變只在(zai)較低的應(ying)變速率下出現，并(bing)由此導(dao)(dao)致脆(cui)(cui)(cui)(cui)性(xing)斷裂(lie)，一(yi)旦出現氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)化物，即使卸(xie)載除氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)，靜止一(yi)段(duan)時(shi)(shi)間后再高速變形(xing)(xing)(xing)，塑性(xing)也(ye)不能(neng)恢復(fu)，故也(ye)是(shi)不可(ke)逆(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。二(er)是(shi)可(ke)逆(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。是(shi)指(zhi)含氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)金屬在(zai)高速變形(xing)(xing)(xing)時(shi)(shi)并(bing)不顯示脆(cui)(cui)(cui)(cui)性(xing)，而(er)在(zai)緩慢變形(xing)(xing)(xing)時(shi)(shi)由于氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)逐(zhu)(zhu)漸向應(ying)力(li)集(ji)中(zhong)(zhong)處富(fu)集(ji)，在(zai)應(ying)力(li)與氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)交互(hu)作用下裂(lie)紋(wen)形(xing)(xing)(xing)核、擴展，最終導(dao)(dao)致脆(cui)(cui)(cui)(cui)性(xing)的斷裂(lie)，在(zai)未形(xing)(xing)(xing)成(cheng)裂(lie)紋(wen)前去除載荷，靜置一(yi)段(duan)時(shi)(shi)間后高速變形(xing)(xing)(xing)，材料(liao)的塑性(xing)可(ke)以得到恢復(fu)，即應(ying)力(li)去除后脆(cui)(cui)(cui)(cui)性(xing)消失，因此稱為可(ke)逆(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。由內氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)引起(qi)(qi)的稱可(ke)逆(ni)內氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)，由外氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)引起(qi)(qi)的稱環境(jing)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。通常所說(shuo)的氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)主(zhu)要指(zhi)可(ke)逆(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)，是(shi)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)致開(kai)裂(lie)中(zhong)(zhong)最主(zhu)要、最危險的破壞形(xing)(xing)(xing)式。