S30408钢应变强化效果的声发射测试实验研究

Experimental study of S30408 steel strain strengthening effect by acoustic emission measurement

根据Kaiser效应和应变强化原理,提出利用声发射特征参数确定Kaiser效应临界点应力,通过计算Felicity比值来对应变强化效果进行评估的方法。以S30408钢为例,对其应变强化过程及强化后二次加载过程进行声发射测试,实验结果表明,利用声发射累计能量和累计振铃计数等特征参数时间历程图,可得到试件应变强化后Kaiser效应点应力值。通过对实验数据的计算与分析,得到不同加载速率下各试件的Felicity比值均大于0.9,且在2.0mm/min加载速率下,Felicity比值最高,说明在该加载速率下应变强化效果最为理想。

According to Kaiser effect and the principle of strain strengthening,a method of determining critical point stress of Kaiser effect is put forward in this paper by using acoustic emission characteristic parameters,and then strain strengthening effect is evaluated by calculating Felicity ratio.Taking s30408 steel as an example,the strain strengthening process and the secondary loading process after strengthening were tested by acoustic emission.Experimental results show that the Kaiser effect point stress values of the after-hardening specimens can be obtained by using the time charts of characteristic parameters such as acoustic emission cumulative energy and cumulative count.Through the calculation and analysis of the experimental data,the Felicity ratios of all specimens under different loading rates are all greater than 0.9,and the Felicity ratio is the highest under 2.0 mm/min loading rate,which shows that the strain hardening effect is the most ideal under this loading rate.