40Cr钢链轮开裂失效分析
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摘要
40Cr链轮在精加工内孔时发生开裂,链轮不能使用。通过断口分析、成分分析、硬度测试、金相分析、低倍检验等工作,对链轮的开裂原因进行了分析。结果表明:该链轮断口呈明显的脆性断裂特征,化学成分满足40Cr钢要求,表面淬火硬化层硬度梯度较大,金属夹杂物超标,芯部显微组织有网状铁素体,低倍试片酸侵后存在裂纹。因链轮的基体强度低和表面淬火位置存在较大组织应力,易于裂纹的形成和扩展,但氢脆引起的延迟断裂是该链轮开裂的主要原因。
The sprocket was scrapped because of the sprocket cracking of 40 Cr steel during the finishing inner hole. The causes of cracking were analyzed through fracture analysis, chemical composition analysis, hardness test, metallographic analysis, macrostructure test and so on. The results show that the fracture of sprocket has obviously the characteristics of brittle fracture, the chemical composition of sprocket meets the requirements of 40 Cr steel, the hardness gradient of hardened layer is larger, the metal inclusions exceed the standard, the microstructure in core is netty ferrite, and there are cracks in low power sample after acid penetration. The sprocket has low matrix strength and high structural stress at the induction hardening position, which makes the crack is easy to form and propagate. But the delayed fracture caused by hydrogen embrittlement is the main reason of the sprocket cracking.
The sprocket was scrapped because of the sprocket cracking of 40 Cr steel during the finishing inner hole. The causes of cracking were analyzed through fracture analysis, chemical composition analysis, hardness test, metallographic analysis, macrostructure test and so on. The results show that the fracture of sprocket has obviously the characteristics of brittle fracture, the chemical composition of sprocket meets the requirements of 40 Cr steel, the hardness gradient of hardened layer is larger, the metal inclusions exceed the standard, the microstructure in core is netty ferrite, and there are cracks in low power sample after acid penetration. The sprocket has low matrix strength and high structural stress at the induction hardening position, which makes the crack is easy to form and propagate. But the delayed fracture caused by hydrogen embrittlement is the main reason of the sprocket cracking.
引文
[1] 渠清团.40Cr钢内齿轮齿圈断裂失效分析[J].河南科技,2013(15):115-116.
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[4] 雷小波,李锁才,郭文勇,等.某风机主轴断裂失效分析[J].金属热处理,2018,43(5):221-223.
[5] 陈再良,付海峰,吕东显.55CrSi弹簧钢的氢脆断裂分析[J].金属热处理,2011,36(S1):383-387.
[2] 李萍,周昊,王建刚,等.40Cr钢球销裂纹分析与防治措施[J].热处理技术与装备,2016,37(3):21-24.
[3] 张升才,郦剑,罗娟,等.汽车后桥半轴断裂失效分析[J].金属热处理,2010,35(9):111-114.
[4] 雷小波,李锁才,郭文勇,等.某风机主轴断裂失效分析[J].金属热处理,2018,43(5):221-223.
[5] 陈再良,付海峰,吕东显.55CrSi弹簧钢的氢脆断裂分析[J].金属热处理,2011,36(S1):383-387.