Small punch creep test data for P91 wm material at 600 °C and a load of 240 N

The main aim of the thesis is to demonstrate the suitability of Small Punch (SP) testing for lifetime prediction of metallic materials operating at high temperatures. The lack of standardisation of this technique and doubts about the correlation of the data with that obtained from conventional creep tests, supports the need to exploit the recently launched Code of Practice for Small Punch Testing (CEN/WS 21). The present work is specifically concerned with investigating the creep behaviour of P91 steel weldments at 600 deg.C along with low-temperature fracture behaviour. Thin discs, 8 mm in diameter and 0.5 mm thick, were manufactured from different zones of a component containing a P91 welded joint: base metal (BM), service- exposed material (SE), weld metal (WM), fine-grain and coarse-grain heat affected zones (FG-HAZ & CG-HAZ). The results of SP creep tests on these disks, performed at 600 deg.C under different loads carefully following the Code of Practice, could be correlated with standard creep data. The SP test is shown to be a reliable method to depict creep behaviour of this alloy and its weldments and a creep model derived, useful for life time prediction, could also be demonstrated through FEA to predict the creep deformation of the SP discs. Additionally, the SP testing method shows potential to evaluate the fracture properties of P91 weldments, in particular the ductile-to-brittle transition temperature and fracture toughness estimations.

本论文的主要目的是验证小冲杆（SP）试验在高温服役金属材料寿命预测中的适用性。该技术缺乏标准化，且其数据与传统蠕变试验数据的相关性存在疑问，因此有必要利用最新发布的《小冲杆试验操作规范》（CEN/WS 21）。本研究重点探究600℃下P91钢焊接件的蠕变行为及低温断裂行为。从含P91焊接接头的构件不同区域制备直径8mm、厚度0.5mm的薄圆盘试样，包括母材（BM）、服役暴露材料（SE）、焊缝金属（WM）、细晶热影响区（FG-HAZ）及粗晶热影响区（CG-HAZ）。严格遵循该操作规范，在600℃不同载荷下对这些圆盘试样进行SP蠕变试验，其结果可与标准蠕变数据关联。结果表明，SP试验是描述该合金及其焊接件蠕变行为的可靠方法；此外，通过有限元分析（FEA）可验证所推导的蠕变模型（适用于寿命预测）能够预测SP圆盘试样的蠕变变形。此外，SP试验方法在评估P91焊接件断裂性能方面具有潜力，尤其是在韧脆转变温度和断裂韧性估算方面。