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(cui)

 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)況將造成金(jin)屬永久損(sun)傷，使材料(liao)塑(su)性或(huo)強(qiang)度(du)降低，即使從金(jin)屬中除(chu)(chu)氫損(sun)傷也不能消除(chu)(chu)，塑(su)性或(huo)強(qiang)度(du)也不能恢復，故稱為不可逆氫脆。

2. 第二類氫脆

 氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)的(de)(de)敏感性(xing)隨應(ying)變(bian)(bian)(bian)速率增加而(er)降(jiang)低(di)(di)，即材料在(zai)(zai)(zai)加載(zai)前(qian)并(bing)不存在(zai)(zai)(zai)裂(lie)紋(wen)(wen)源(yuan)，加載(zai)后(hou)在(zai)(zai)(zai)應(ying)力(li)(li)和(he)氫(qing)(qing)(qing)(qing)(qing)(qing)的(de)(de)交互作用(yong)下(xia)(xia)逐(zhu)漸形(xing)(xing)(xing)成(cheng)裂(lie)紋(wen)(wen)源(yuan)，最(zui)終導致(zhi)(zhi)脆(cui)(cui)(cui)(cui)性(xing)斷裂(lie)。第二(er)類(lei)氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)包括兩種形(xing)(xing)(xing)式：一是(shi)(shi)應(ying)力(li)(li)誘(you)發氫(qing)(qing)(qing)(qing)(qing)(qing)化物(wu)型氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。在(zai)(zai)(zai)能夠形(xing)(xing)(xing)成(cheng)脆(cui)(cui)(cui)(cui)性(xing)氫(qing)(qing)(qing)(qing)(qing)(qing)化物(wu)的(de)(de)金屬中(zhong)，當氫(qing)(qing)(qing)(qing)(qing)(qing)含(han)量較(jiao)低(di)(di)或氫(qing)(qing)(qing)(qing)(qing)(qing)在(zai)(zai)(zai)固溶(rong)體中(zhong)的(de)(de)過飽(bao)和(he)度(du)較(jiao)低(di)(di)時(shi)(shi)，尚(shang)不能自發形(xing)(xing)(xing)成(cheng)氫(qing)(qing)(qing)(qing)(qing)(qing)化物(wu)；而(er)在(zai)(zai)(zai)應(ying)力(li)(li)作用(yong)下(xia)(xia)，氫(qing)(qing)(qing)(qing)(qing)(qing)會(hui)向應(ying)力(li)(li)集(ji)(ji)中(zhong)處(chu)富(fu)集(ji)(ji)，當氫(qing)(qing)(qing)(qing)(qing)(qing)濃度(du)超(chao)過臨界(jie)值時(shi)(shi)就會(hui)沉淀出(chu)氫(qing)(qing)(qing)(qing)(qing)(qing)化物(wu)。這(zhe)種應(ying)力(li)(li)誘(you)發的(de)(de)氫(qing)(qing)(qing)(qing)(qing)(qing)化物(wu)相變(bian)(bian)(bian)只在(zai)(zai)(zai)較(jiao)低(di)(di)的(de)(de)應(ying)變(bian)(bian)(bian)速率下(xia)(xia)出(chu)現，并(bing)由此導致(zhi)(zhi)脆(cui)(cui)(cui)(cui)性(xing)斷裂(lie)，一旦出(chu)現氫(qing)(qing)(qing)(qing)(qing)(qing)化物(wu)，即使卸載(zai)除氫(qing)(qing)(qing)(qing)(qing)(qing)，靜止一段(duan)時(shi)(shi)間后(hou)再高速變(bian)(bian)(bian)形(xing)(xing)(xing)，塑性(xing)也(ye)不能恢復(fu)，故也(ye)是(shi)(shi)不可(ke)逆(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。二(er)是(shi)(shi)可(ke)逆(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。是(shi)(shi)指含(han)氫(qing)(qing)(qing)(qing)(qing)(qing)金屬在(zai)(zai)(zai)高速變(bian)(bian)(bian)形(xing)(xing)(xing)時(shi)(shi)并(bing)不顯示脆(cui)(cui)(cui)(cui)性(xing)，而(er)在(zai)(zai)(zai)緩慢變(bian)(bian)(bian)形(xing)(xing)(xing)時(shi)(shi)由于(yu)氫(qing)(qing)(qing)(qing)(qing)(qing)逐(zhu)漸向應(ying)力(li)(li)集(ji)(ji)中(zhong)處(chu)富(fu)集(ji)(ji)，在(zai)(zai)(zai)應(ying)力(li)(li)與氫(qing)(qing)(qing)(qing)(qing)(qing)交互作用(yong)下(xia)(xia)裂(lie)紋(wen)(wen)形(xing)(xing)(xing)核、擴展，最(zui)終導致(zhi)(zhi)脆(cui)(cui)(cui)(cui)性(xing)的(de)(de)斷裂(lie)，在(zai)(zai)(zai)未(wei)形(xing)(xing)(xing)成(cheng)裂(lie)紋(wen)(wen)前(qian)去除載(zai)荷，靜置一段(duan)時(shi)(shi)間后(hou)高速變(bian)(bian)(bian)形(xing)(xing)(xing)，材料的(de)(de)塑性(xing)可(ke)以得(de)到(dao)恢復(fu)，即應(ying)力(li)(li)去除后(hou)脆(cui)(cui)(cui)(cui)性(xing)消(xiao)失，因此稱(cheng)為可(ke)逆(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。由內(nei)氫(qing)(qing)(qing)(qing)(qing)(qing)引起的(de)(de)稱(cheng)可(ke)逆(ni)內(nei)氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)，由外氫(qing)(qing)(qing)(qing)(qing)(qing)引起的(de)(de)稱(cheng)環境氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)。通(tong)常(chang)所(suo)說的(de)(de)氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)主(zhu)要指可(ke)逆(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)，是(shi)(shi)氫(qing)(qing)(qing)(qing)(qing)(qing)致(zhi)(zhi)開裂(lie)中(zhong)最(zui)主(zhu)要、最(zui)危險的(de)(de)破壞形(xing)(xing)(xing)式。