【摘要】 研究了热输入量不同的316LN不锈钢焊接接头在沸腾硝酸溶液中的晶间腐蚀特性,结果表明:焊接热输入量越大,焊接接头的抗晶间腐蚀性能越差;焊接接头焊缝区抗晶间腐蚀能力高于热影响区和母材区;晶间腐蚀过程可分为氧化、钝化、氧化膜裂纹萌生、氧化膜裂纹扩展和高速晶间腐蚀等阶段;在不同阶段声发射信号中氧化信号在20 k Hz的频率位置有能量峰,钝化信号在40 k Hz频率处有明显能量峰的突发型信号,氧化膜裂纹萌生信号在80-100 k Hz的频率段内有明显能量峰的突发型信号,氧化膜裂纹扩展信号具有60 k Hz倍频关系,高速晶间腐蚀信号是一种持续时间稍长的突发型信号,在50 k Hz处有明显的能量峰。更多还原

【Abstract】 The intergranular corrosion characteristics of 316 LN austenitic stainless steel welded joints with different welding heat input in boiling nitric acid solution were investigated by metallography analysis and acoustic emission technology. The results show that the resistance to intergranular corrosion of welded joints deteriorated with the increasing welding heat input. The intergranular corrosion resistance of the weld zone is better than that of the heat affected zone and the base material. Five stages for the intergranular corrosion process can be differentiated according to the characteristics of the detected acoustic emission spectrum, such as oxidation, passivation, oxide film crack initiation, oxide film crack propagation and finally fast intergranular corrosion. In other words, in the acoustic emission spectrum,there exist an obvious energy peak by 20 k Hz representing the oxidation signal; an obvious energy peak by 40 k Hz of a burst-like signal representing the stage of passivation process; energy peaks in a range80 to 100 k Hz of burst-like signal representing the oxide film crack initiation; energy peaks by frequency of 60 k Hz representing the stage of crack propagation; and finally a peak by 50 k Hz of a burst-like signal with a slightly longer duration representing the stage of fast intergranular corrosion.更多还原