X10CrAlSi18耐热钢的蠕变性能及寿命预测

Creep property and life prediction of X10CrAlSi18 heat-resistant steel

采用高温蠕变试验,对铁素体耐热不锈钢X10CrAlSi18在不同温度及应力条件下的高温蠕变行为进行了研究。结果表明,在温度一定的条件下,随着应力的增加试验钢的蠕变寿命缩短,最小蠕变速率增加。700℃/15 MPa和750℃/10 MPa时的蠕变寿命较长,分别为491.449 h和356.049 h。扫描电镜(SEM)观察分析表明,试验钢的蠕变断裂模式为沿晶和穿晶混合断裂。在应力一定的条件下,随着温度增加,韧窝平均直径增大,深度增加,且大韧窝周围有细小韧窝和蠕变空洞。研究表明,应力与最小蠕变速率满足幂律关系,700℃和750℃蠕变应力指数分别为4.37344和4.37528,蠕变机制主要为位错蠕变。基于修正的θ投影法,建立了试验钢在700℃、750℃蠕变寿命预测模型。

High temperature creep test was used to study the high temperature creep behavior of ferrite heat-resistant stainless steel X10 CrAlSi18 under different temperature and stress conditions. The results show that the creep life of the tested steel decreases and the minimum creep rate increases with the increase of stress under a given temperature. The creep life at 700 ℃/15 MPa and 750 ℃/10 MPa is long, which is 491.449 h and 356.049 h, respectively. The scanning electron microscopy(SEM) analysis results show that the creep fracture mode of the tested steel is a mix of intergranular and transgranular fracture. Under a given stress, with the increase of temperature, the average diameter and depth of dimples increase, and there are fine dimples and creep cavities around the large dimples. The relation between stress and minimum creep rate is power-rate relation, the creep stress indexes at 700 ℃ and 750 ℃ are 4.37344 and 4.37528, respectively, and the creep mechanism is mainly dislocation creep. The creep life prediction model of the tested steel at 700 ℃ and 750 ℃ is established based on the modified theta projection method.