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(qing)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。

 上述三種情(qing)況將造成金屬永(yong)久損(sun)(sun)傷(shang)，使材料塑性或強度降低，即使從金屬中除(chu)氫損(sun)(sun)傷(shang)也(ye)不(bu)能消除(chu)，塑性或強度也(ye)不(bu)能恢復，故(gu)稱為不(bu)可逆(ni)氫脆(cui)。

2. 第二類氫(qing)脆

 氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)(cui)的(de)(de)敏感(gan)性(xing)隨(sui)應(ying)變(bian)(bian)速率增加(jia)而(er)降低(di)，即材料(liao)在(zai)(zai)加(jia)載前并(bing)不(bu)存(cun)在(zai)(zai)裂(lie)紋源，加(jia)載后(hou)在(zai)(zai)應(ying)力和(he)氫(qing)(qing)(qing)(qing)(qing)(qing)的(de)(de)交(jiao)互作(zuo)用(yong)下(xia)逐漸(jian)形成(cheng)裂(lie)紋源，最終(zhong)導致(zhi)脆(cui)(cui)(cui)(cui)(cui)(cui)性(xing)斷(duan)裂(lie)。第(di)二類氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)(cui)包括兩(liang)種形式(shi)：一是應(ying)力誘發(fa)氫(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物(wu)型氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)(cui)。在(zai)(zai)能夠形成(cheng)脆(cui)(cui)(cui)(cui)(cui)(cui)性(xing)氫(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物(wu)的(de)(de)金屬(shu)中(zhong)(zhong)，當氫(qing)(qing)(qing)(qing)(qing)(qing)含(han)(han)量較(jiao)低(di)或氫(qing)(qing)(qing)(qing)(qing)(qing)在(zai)(zai)固溶體中(zhong)(zhong)的(de)(de)過飽和(he)度(du)較(jiao)低(di)時，尚不(bu)能自(zi)發(fa)形成(cheng)氫(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物(wu)；而(er)在(zai)(zai)應(ying)力作(zuo)用(yong)下(xia)，氫(qing)(qing)(qing)(qing)(qing)(qing)會向應(ying)力集中(zhong)(zhong)處富集，當氫(qing)(qing)(qing)(qing)(qing)(qing)濃(nong)度(du)超(chao)過臨界(jie)值時就(jiu)會沉淀出氫(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物(wu)。這(zhe)種應(ying)力誘發(fa)的(de)(de)氫(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物(wu)相變(bian)(bian)只在(zai)(zai)較(jiao)低(di)的(de)(de)應(ying)變(bian)(bian)速率下(xia)出現(xian)，并(bing)由(you)此導致(zhi)脆(cui)(cui)(cui)(cui)(cui)(cui)性(xing)斷(duan)裂(lie)，一旦出現(xian)氫(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物(wu)，即使卸(xie)載除氫(qing)(qing)(qing)(qing)(qing)(qing)，靜(jing)止一段時間(jian)后(hou)再高(gao)速變(bian)(bian)形，塑性(xing)也不(bu)能恢復，故也是不(bu)可(ke)逆(ni)(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)(cui)。二是可(ke)逆(ni)(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)(cui)。是指(zhi)含(han)(han)氫(qing)(qing)(qing)(qing)(qing)(qing)金屬(shu)在(zai)(zai)高(gao)速變(bian)(bian)形時并(bing)不(bu)顯示(shi)脆(cui)(cui)(cui)(cui)(cui)(cui)性(xing)，而(er)在(zai)(zai)緩慢變(bian)(bian)形時由(you)于氫(qing)(qing)(qing)(qing)(qing)(qing)逐漸(jian)向應(ying)力集中(zhong)(zhong)處富集，在(zai)(zai)應(ying)力與氫(qing)(qing)(qing)(qing)(qing)(qing)交(jiao)互作(zuo)用(yong)下(xia)裂(lie)紋形核、擴展，最終(zhong)導致(zhi)脆(cui)(cui)(cui)(cui)(cui)(cui)性(xing)的(de)(de)斷(duan)裂(lie)，在(zai)(zai)未(wei)形成(cheng)裂(lie)紋前去除載荷，靜(jing)置(zhi)一段時間(jian)后(hou)高(gao)速變(bian)(bian)形，材料(liao)的(de)(de)塑性(xing)可(ke)以得(de)到恢復，即應(ying)力去除后(hou)脆(cui)(cui)(cui)(cui)(cui)(cui)性(xing)消失，因此稱為可(ke)逆(ni)(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)(cui)。由(you)內氫(qing)(qing)(qing)(qing)(qing)(qing)引起的(de)(de)稱可(ke)逆(ni)(ni)內氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)(cui)，由(you)外氫(qing)(qing)(qing)(qing)(qing)(qing)引起的(de)(de)稱環境氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)(cui)。通常所說的(de)(de)氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)(cui)主(zhu)要指(zhi)可(ke)逆(ni)(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)(cui)，是氫(qing)(qing)(qing)(qing)(qing)(qing)致(zhi)開裂(lie)中(zhong)(zhong)最主(zhu)要、最危(wei)險的(de)(de)破壞形式(shi)。