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。

 上述三種情況將造成金(jin)屬永久(jiu)損傷，使(shi)材料塑性或強(qiang)度(du)降低，即使(shi)從(cong)金(jin)屬中(zhong)除氫(qing)損傷也(ye)不(bu)能消除，塑性或強(qiang)度(du)也(ye)不(bu)能恢復，故(gu)稱為(wei)不(bu)可逆氫(qing)脆。

2. 第二(er)類氫脆

 氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)的(de)(de)(de)敏感性(xing)(xing)隨應(ying)(ying)(ying)(ying)變(bian)速率(lv)增(zeng)加而(er)降(jiang)低(di)，即材(cai)料(liao)在(zai)(zai)(zai)(zai)加載(zai)前并(bing)不(bu)存在(zai)(zai)(zai)(zai)裂紋(wen)源，加載(zai)后在(zai)(zai)(zai)(zai)應(ying)(ying)(ying)(ying)力和氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)的(de)(de)(de)交(jiao)互(hu)作用(yong)下(xia)逐(zhu)漸形(xing)成(cheng)(cheng)裂紋(wen)源，最(zui)終(zhong)導(dao)致(zhi)脆(cui)(cui)(cui)(cui)(cui)性(xing)(xing)斷裂。第(di)二類氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)包(bao)括兩種形(xing)式：一(yi)(yi)是(shi)(shi)(shi)應(ying)(ying)(ying)(ying)力誘(you)發(fa)(fa)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物型氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)。在(zai)(zai)(zai)(zai)能(neng)夠形(xing)成(cheng)(cheng)脆(cui)(cui)(cui)(cui)(cui)性(xing)(xing)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物的(de)(de)(de)金屬(shu)中(zhong)(zhong)，當氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)含量較(jiao)低(di)或氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)在(zai)(zai)(zai)(zai)固溶體中(zhong)(zhong)的(de)(de)(de)過飽和度較(jiao)低(di)時(shi)，尚(shang)不(bu)能(neng)自(zi)發(fa)(fa)形(xing)成(cheng)(cheng)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物；而(er)在(zai)(zai)(zai)(zai)應(ying)(ying)(ying)(ying)力作用(yong)下(xia)，氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)會向應(ying)(ying)(ying)(ying)力集(ji)中(zhong)(zhong)處富(fu)(fu)集(ji)，當氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)濃度超過臨界值時(shi)就會沉淀出(chu)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物。這種應(ying)(ying)(ying)(ying)力誘(you)發(fa)(fa)的(de)(de)(de)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物相(xiang)變(bian)只在(zai)(zai)(zai)(zai)較(jiao)低(di)的(de)(de)(de)應(ying)(ying)(ying)(ying)變(bian)速率(lv)下(xia)出(chu)現(xian)(xian)，并(bing)由此導(dao)致(zhi)脆(cui)(cui)(cui)(cui)(cui)性(xing)(xing)斷裂，一(yi)(yi)旦出(chu)現(xian)(xian)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)化(hua)(hua)物，即使卸載(zai)除氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)，靜(jing)止一(yi)(yi)段時(shi)間(jian)(jian)后再高速變(bian)形(xing)，塑性(xing)(xing)也不(bu)能(neng)恢復，故(gu)也是(shi)(shi)(shi)不(bu)可(ke)(ke)逆(ni)(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)。二是(shi)(shi)(shi)可(ke)(ke)逆(ni)(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)。是(shi)(shi)(shi)指(zhi)(zhi)含氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)金屬(shu)在(zai)(zai)(zai)(zai)高速變(bian)形(xing)時(shi)并(bing)不(bu)顯示脆(cui)(cui)(cui)(cui)(cui)性(xing)(xing)，而(er)在(zai)(zai)(zai)(zai)緩慢變(bian)形(xing)時(shi)由于(yu)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)逐(zhu)漸向應(ying)(ying)(ying)(ying)力集(ji)中(zhong)(zhong)處富(fu)(fu)集(ji)，在(zai)(zai)(zai)(zai)應(ying)(ying)(ying)(ying)力與氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)交(jiao)互(hu)作用(yong)下(xia)裂紋(wen)形(xing)核、擴(kuo)展，最(zui)終(zhong)導(dao)致(zhi)脆(cui)(cui)(cui)(cui)(cui)性(xing)(xing)的(de)(de)(de)斷裂，在(zai)(zai)(zai)(zai)未形(xing)成(cheng)(cheng)裂紋(wen)前去(qu)除載(zai)荷，靜(jing)置一(yi)(yi)段時(shi)間(jian)(jian)后高速變(bian)形(xing)，材(cai)料(liao)的(de)(de)(de)塑性(xing)(xing)可(ke)(ke)以得(de)到恢復，即應(ying)(ying)(ying)(ying)力去(qu)除后脆(cui)(cui)(cui)(cui)(cui)性(xing)(xing)消(xiao)失，因此稱(cheng)為可(ke)(ke)逆(ni)(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)。由內(nei)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)引起的(de)(de)(de)稱(cheng)可(ke)(ke)逆(ni)(ni)內(nei)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)，由外氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)引起的(de)(de)(de)稱(cheng)環境氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)。通常所說的(de)(de)(de)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)主要(yao)指(zhi)(zhi)可(ke)(ke)逆(ni)(ni)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)脆(cui)(cui)(cui)(cui)(cui)，是(shi)(shi)(shi)氫(qing)(qing)(qing)(qing)(qing)(qing)(qing)(qing)致(zhi)開裂中(zhong)(zhong)最(zui)主要(yao)、最(zui)危險的(de)(de)(de)破壞形(xing)式。