低活性Fe-Cr-Mn(W,V)奥氏体合金长期时效高温力学性能和相稳定性研究

研究了用于核反应堆中的低活性Fe -Cr-Mn(W ,V)奥氏体合金不同温度长期时效 (10 0 0h)后的高温拉伸性能 (40 0℃ )及相稳定性。结果表明 :Fe -Cr -Mn(W ,V)奥氏体合金经长期时效后 4 0 0℃时的屈服强度 (或σ0 2 ,40 0℃)随时效温度从 35 0℃至 4 5 0℃上升变化不大 ,4 5 0℃至 5 5 0℃从 2 95MPa上升到 4 4 4MPa,5 5 0℃至 6 5 0℃保持在 4 90MPa左右 ;抗拉强度 (σb)在 35 0℃至 4 5 0℃比较平稳 ,4 5 0℃至 5 5 0℃从 6 38MPa上升到 75 9MPa ,5 5 0℃至6 5 0℃保持在 75 0MPa左右 ;合金延伸率 (δ/ % ) 35 0℃至 4 5 0℃比较稳定 ,4 5 0℃至 5 5 0℃下降较快 ,在 5 5 0℃至 6 5 0℃下降比较平缓 ,6 5 0℃时δ值为 19%左右。合金经不同温度 (35 0℃～ 6 5 0℃ )长期时效组织为稳定的奥氏体相及少量碳化物 ,在 4 5 0℃以下长期时效 ,合金中无大量碳化物析出 ,4 5 0℃以上时效时 ,碳化物析出量明显增加 ,6 5 0℃时在晶界集聚 ,导致合金拉伸强度上升而塑性下降

Study on high temperature tensile property and microstructure stability of low activation Fe-Cr-Mn(W,V)austenitic alloy aged for 1000h under different temperatures

The high temperature mechanical properties and the microstructure stability of low activation Fe-Cr-Mn(W,V)austenitic alloy after long time (1000h) age under different temperatures were studied in this paper.The results indicated that the high temperature tensile strength(σ b )and yield strength(σ 0.2 )of the alloy had a sudden increase after being aged from 450℃ to 550℃,σ 0.2 increased from 295MPa to 444MPa and σ b from 638MPa to 759MPa.The elongation(δ)reduced a little as the aging temperature below 450℃;while the temperature above 450℃,it reduced quickly especially during 450℃ to 550℃.But the δ still above 19% even at 650℃.There were a stable austenitic phase and a few carbides in the Fe-Cr-Mn(W,V) austenitic alloy after long time(1000h) age from 350℃ to 650℃.It also seemed that the carbides increased obviously in the alloy aged above 450℃,which led to the increase of high temperature tensile strength and the decrease of ductility.