研究了Inconel 625镍基高温合金焊接接头在25和760℃下的低周疲劳行为,分析了2种温度下焊接接头的应变疲劳寿命数据和循环应力-应变数据,进而给出了合金焊接接头的应变疲劳参数.结果表明,Inconel 625镍基高温合金焊接接头在不同温度下的弹性应变幅和塑性应变幅与载荷反向周次的关系可分别用Basquin和Coffin-Manson公式来描述.合金焊接接头在25℃下疲劳变形时,主要发生循环软化,而在760℃下疲劳变形时则呈现循环硬化.焊接接头的低周疲劳裂纹以穿晶方式萌生于疲劳试样的自由表面,在25℃下疲劳裂纹以穿晶方式扩展,而在760℃下疲劳裂纹则以穿晶和沿晶混合方式扩展.
The low-cycle fatigue tests of Inconel 625 nickel-based superalloy welding joints at 25 and 760 ℃ were performed.The strain-fatigue life data and cyclic stress-strain data were analyzed to determine the strain fatigue parameters of Inconel 625 superalloy welding joints.The result showed that the relationship between elastic strain amplitude,plastic strain amplitude and reversals to failure could be described by Basquin and CoffinManson equations,respectively.Under the strain control,the continuous cyclic softening was observed at 25 ℃,however,the cyclic hardening appeared at 760 ℃.At 25 ℃,the fatigue crack of Inconel 625 superalloy welding joints initiated transgranularly at the specimen surface and propagated in the transgranular mode.Differently,at 760 ℃,the fatigue crack initiated transgranularly at the specimen surface,but propagated in mixed transgranular and intergranular modes.
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