高温热冲击对J75不锈钢力学性能及微观组织的影响

EFFECT OF HIGH TEMPERATURE THERMAL SHOCKING ON THE MECHANICAL PROPERTY AND MICROSTRUCTURE OF STAINLESS STEEL J75

研究了沉淀强化奥氏体不锈钢J75经受不同温度热冲击及一定温度下多次热冲击作用后的力学性能变化规律,并探索了性能损伤机理.研究结果表明,在作用时间为1s的情况下,温度低于610℃,单次或多次热冲击对合金的力学性能无明显损伤;温度高于750℃;热冲击明显影响合金的力学性能,强度和延伸率都随热冲击次数增加明显降低.显微分析表明,热冲击温度和热冲击次数的增加,促进了晶粒细化,也使材料的析出相发生了明显的变化.在高于750℃下产生的大量片状η相的析出及γ强化相的粗化和不均匀分布,是引起J75不锈钢强度和延伸率显著下降的主要原因.

The mechanical property change and property damage mechanism of austenitic precipitation-hardened stainless steel J75, under different temperature thermal shockings and several thermal shockings at some certain temperatures, were investigated. The experiment results indicated that, in the case of impact within Is, the strength and elongation of the alloy have no change when the single or multi thermal shocking temperatures are below 610 degreesC, but decreased evidently above 750 degreesC with increase of thermal shocking frequency. The microscopic analysis showed that, increasing the temperature and frequency of thermal shocking would refine the grain and make the precipitation phase change apparently. When the temperature was above 750 V, a large amount of platelet 77 phase would precipitate and gamma' phase would coarse and distribute inhomogeneously, which are the main reason for the apparent decrease of the alloy strength and elongation.