34Cr2Ni2Mo鋼法蘭叉頭異?，F(xiàn)象成因分析

34Cr2Ni2Mo鋼法蘭叉頭異?，F(xiàn)象成因分析Cause Analysis on Abnormal Phenomenon of 34Cr2Ni2Mo Steel Flange Forks

某批34Cr2Ni2Mo鋼法蘭叉頭在調(diào)質(zhì)處理后的機(jī)加工過(guò)程中，在軸承孔內(nèi)靠近法蘭一面發(fā)現(xiàn)多條白色帶狀異常區(qū)域，通過(guò)低倍檢驗(yàn)、化學(xué)成分分析、硬度試驗(yàn)和金相檢驗(yàn)等方法對(duì)其成因進(jìn)行了分析。結(jié)果表明：在34Cr2Ni2Mo鋼法蘭叉頭鑄造過(guò)程中，由于20鋼內(nèi)冷鐵支架固定不穩(wěn)，澆鑄時(shí)受鋼液的沖刷作用坍塌堆積于鑄件內(nèi)，并在隨后機(jī)加工過(guò)程中在軸承孔內(nèi)靠近法蘭一面露出表面，從而形成異于基體的白色帶狀異常區(qū)域。

Multi white banded abnormal areas were found in the bearing hole close to the flange side of a batch of 34Cr2Ni2Mo steel flange forks in machining process after quenching and tempering, and the causes were analyzed by means of macro-etching test, chemical composition analysis, hardness test and metallographic examination. The results show in the casting process of 34Cr2Ni2Mo steel flange forks, due to fixing instability, the 20 steel internal chill frame collapsed and stored in the casting under the scouring action of molten steel. The 20 steel was exposed in the bearing hole close to the flange side in the following machining process, so white banded abnormal areas different from the matrix produced.