服役态HR3C耐热钢管的缺口敏感性

Notch sensitivity of in-service HR3C heat resistant steel tube

在服役态HR3C耐热钢管显微组织结构研究的基础上,比较有无缺口HR3C耐热钢管试样的拉伸性能及断口形貌的差异,评价服役态HR3C耐热钢的缺口敏感性。结果表明:605℃服役导致HR3C耐热钢中奥氏体晶粒长大,在奥氏体晶界、孪晶界析出M23C6,导致其强度增加,塑性下降。缺口导致供货态及服役态HR3C耐热钢抗拉强度及伸长率下降,但屈服强度增大。随着服役时间的延长,伴随着组织老化,服役态HR3C耐热钢的缺口敏感性增加。HR3C耐热钢管表面划伤造成尖端应力集中,导致服役态HR3C耐热钢管强度损失严重,甚至爆管失效。

On the basis of the study of microstructure of in-service HR3 C heat-resistant steel tube, the difference of tensile properties and fracture morphology of the HR3 C heat-resistant steel tube specimens with or without notch was compared, and the notch sensitivity of the in-service HR3 C heat-resistant steel was evaluated. The results show that after serving at 605 ℃, the austenite grain of the HR3 C heat-resistant steel grows and the M23C6 precipitates at the austenite grain/twin boundaries, resulting in the increase of strength and the decrease of elongation. The tensile strength and elongation of the as-received and in-service heat resistant steel decrease due to the notch, but the yield strength increases. With the increase of the service time, the notch sensitivity of the in-service HR3 C heat-resistant steel increases. Surface scratch of the HR3 C heat-resistant steel tube will cause tip stress concentration, resulting in serious strength loss, and even burst failure.