leometwu的部落格

1985年 所做檢驗. Inspected in 1985 . A bent-and-welded loop, pickled and hot-dip zinc coated. All loops cracked open after hot-dip zinc coating . Tensile stress induced after bending the loop. H atoms were picked-up during pickling. Upon hot-dipping of zinc, H atoms diffused to grain boundaries and form H2 and expanded and, cracked open the loop.

直徑~25mm 高拉力鋼條 尾端彎折一淚滴形圈圈  焊住   酸洗後因氫脆化  熱浸鍍鋅後 圈圈全裂開

氫脆裂裂紋會往左右兩側大角度分歧(多條裂紋, 多方向). 淬裂通常只向前蔓延 左右分歧少(單條裂紋 單方向)

氫脆裂之產生: 氫原子往鋼內躦(通常 HRC 35以上較會 硬度越高 越容易;  表面有殘留拉應力, 雖硬度不高也會) 然後聚集到鋼晶界成為氫分子(H2)---(氣體有体積), 對鋼的晶界形成一股撐開的力量