http://www.eng-tips.com/viewthread.cfm?qid=322083
問: I have a 6" diameter chrome plated bar C1045 steel that is induction hardened to 60 HRc on the surface with a case depth of around .050". My customer found the bar in the condition as shown in the attached picture. The bar didn't look like this before we shipped it. Not sure if this is a quench crack or a stress induced brittle fracture. One thing that confused me is, there is an area on the bar that shows a drop in hardness to 30 HRc right where I believe the crack initiated. The hardness is 62 HRc about an inch before the start and about an inch into the cracked area. What are some suggestions on how to re-create this type of fracture?
冶金達人 答:This looks like delayed cracking from hydrogen embrittlement. Was the shaft baked (heated to 450-500 deg F) after chrome plating?
S45C ; 直徑~150 mm; HRC 60 高週波硬化層1.25 mm; 研磨後鍍鉻; 出廠時好好的, 經好幾天後 客戶收到時, 發現裂紋.
這是典型的 延遲的氫脆化裂紋: 多處, 多方向大角度分歧是其形貌上的特徵. 肇因:電鍍後未烘烤去氫.
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