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(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。

 上述三種情況將造成(cheng)金屬永久(jiu)損傷，使(shi)材(cai)料(liao)塑性或強度降低，即使(shi)從金屬中除(chu)氫(qing)損傷也(ye)(ye)不能消除(chu)，塑性或強度也(ye)(ye)不能恢(hui)復，故稱為不可逆氫(qing)脆。

2. 第(di)二(er)類氫(qing)脆(cui)

 氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)的敏感性(xing)(xing)(xing)隨應(ying)(ying)變速(su)(su)率增加而(er)降低，即材料在(zai)(zai)(zai)(zai)加載(zai)前并(bing)(bing)不存在(zai)(zai)(zai)(zai)裂紋源，加載(zai)后(hou)在(zai)(zai)(zai)(zai)應(ying)(ying)力(li)和氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)的交(jiao)(jiao)互(hu)作用(yong)下逐(zhu)(zhu)漸(jian)形(xing)(xing)(xing)成(cheng)裂紋源，最(zui)終導致(zhi)脆(cui)(cui)性(xing)(xing)(xing)斷裂。第二類氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)包括兩種形(xing)(xing)(xing)式：一是(shi)(shi)應(ying)(ying)力(li)誘(you)發氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物(wu)(wu)型氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)。在(zai)(zai)(zai)(zai)能(neng)夠形(xing)(xing)(xing)成(cheng)脆(cui)(cui)性(xing)(xing)(xing)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物(wu)(wu)的金屬(shu)中，當(dang)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)含量較(jiao)(jiao)低或氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)在(zai)(zai)(zai)(zai)固溶體(ti)中的過飽和度較(jiao)(jiao)低時(shi)，尚不能(neng)自發形(xing)(xing)(xing)成(cheng)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物(wu)(wu)；而(er)在(zai)(zai)(zai)(zai)應(ying)(ying)力(li)作用(yong)下，氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)會向應(ying)(ying)力(li)集中處(chu)(chu)富(fu)集，當(dang)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)濃度超過臨界值時(shi)就會沉淀出氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物(wu)(wu)。這種應(ying)(ying)力(li)誘(you)發的氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物(wu)(wu)相(xiang)變只在(zai)(zai)(zai)(zai)較(jiao)(jiao)低的應(ying)(ying)變速(su)(su)率下出現，并(bing)(bing)由(you)此導致(zhi)脆(cui)(cui)性(xing)(xing)(xing)斷裂，一旦出現氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物(wu)(wu)，即使卸載(zai)除氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)，靜止一段時(shi)間后(hou)再高(gao)速(su)(su)變形(xing)(xing)(xing)，塑性(xing)(xing)(xing)也不能(neng)恢(hui)復(fu)，故也是(shi)(shi)不可(ke)(ke)(ke)逆氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)。二是(shi)(shi)可(ke)(ke)(ke)逆氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)。是(shi)(shi)指(zhi)含氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)金屬(shu)在(zai)(zai)(zai)(zai)高(gao)速(su)(su)變形(xing)(xing)(xing)時(shi)并(bing)(bing)不顯(xian)示脆(cui)(cui)性(xing)(xing)(xing)，而(er)在(zai)(zai)(zai)(zai)緩慢變形(xing)(xing)(xing)時(shi)由(you)于氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)逐(zhu)(zhu)漸(jian)向應(ying)(ying)力(li)集中處(chu)(chu)富(fu)集，在(zai)(zai)(zai)(zai)應(ying)(ying)力(li)與氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)交(jiao)(jiao)互(hu)作用(yong)下裂紋形(xing)(xing)(xing)核(he)、擴展(zhan)，最(zui)終導致(zhi)脆(cui)(cui)性(xing)(xing)(xing)的斷裂，在(zai)(zai)(zai)(zai)未形(xing)(xing)(xing)成(cheng)裂紋前去除載(zai)荷，靜置一段時(shi)間后(hou)高(gao)速(su)(su)變形(xing)(xing)(xing)，材料的塑性(xing)(xing)(xing)可(ke)(ke)(ke)以得到恢(hui)復(fu)，即應(ying)(ying)力(li)去除后(hou)脆(cui)(cui)性(xing)(xing)(xing)消失，因(yin)此稱(cheng)(cheng)為可(ke)(ke)(ke)逆氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)。由(you)內(nei)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)引起(qi)的稱(cheng)(cheng)可(ke)(ke)(ke)逆內(nei)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)，由(you)外氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)引起(qi)的稱(cheng)(cheng)環境氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)。通常所說(shuo)的氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)主要(yao)指(zhi)可(ke)(ke)(ke)逆氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)，是(shi)(shi)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)致(zhi)開裂中最(zui)主要(yao)、最(zui)危險(xian)的破壞形(xing)(xing)(xing)式。