The present work studies the effects of niobium on the mechanical properties and the elastoplastic/viscoelastic behavior at 927 °C of ASTM A297 grade, HP cast stainless steel in the as-cast material, to simulate the actual work condition. Tensile tests were carried out at different temperatures, differential scanning calorimetry (DSC), relaxation tests, the fatigue of continuous cycles under the triangular waveform, and fatigue with a trapezoidal waveform of the type “Dwell” with dwell times of 120 and 300 s as specified in the E2714-13 standard and hot torsion tests, to analyze the variations in the mechanical properties. The results of the mechanical tests and studies of the microstructural evolution, as well as of its later analyzes, provided data, not only in the form of data sheet's for the application of the values obtained in projects but concurrently after comparing property and microstructure, to deepen the phenomenology of mechanical stress behavior versus monotonic and cyclic deformation, high-temperature deformation mechanisms, dynamic recovery, of the type of microstructure resulting after the tests and also of the fracture mechanisms associated with the types of mechanical stresses imposed on the material, obtained by through the mechanical tests mentioned above. The high-temperature fatigue tests showed expected stress versus strain behavior, where cycles without dwell times showed lower hysteresis area values, from where the energy consumed in a strain cycle is calculated. The increase in the consumed energy values is due to the insertion of the dwell times, but it is important to note that for the tests that contain dwell times of 120 s and 300 s they did not show significant differences between the consumed energy, showing a saturation effect of tension that does not promote more significant inelastic strains. The cyclic mechanical fatigue stresses with dwell times and the low deformation rate led to intense precipitation of secondary carbides Cr₂₃C₆ chromium alloys added to the intrinsic properties of stainless steel dislocation slip were factors that resulted in the dynamic recovery phenomenon. Fractographic analyzes performed on monotonically fractured specimens and specimens after fatigue tests revealed that the material is prone to fracture in intergranular regions.

本工作研究了铌对铸态材料中ASTM A297级，HP铸造不锈钢在927°C下的力学性能和弹塑性/粘弹性行为的影响，以模拟实际工作条件。拉伸试验在不同的温度，差示扫描量热法（DSC），松弛试验，三角波形下连续循环的疲劳以及具有“停留”类型的梯形波形的疲劳（停留时间分别为120和300 s）下进行。符合E2714-13标准和热扭力测试的要求，以分析机械性能的变化。机械测试和微观结构演变研究的结果，以及后来的分析结果，不仅提供了数据表的形式，还提供了数据。适用于应用在项目中获得的值，但在比较性能和微观结构后同时进行的应用，以加深机械应力行为与单调和循环变形，高温变形机制，动态恢复以及测试后产生的微观结构类型的现象以及与通过上述机械测试获得的与施加在材料上的机械应力类型相关的断裂机理。高温疲劳测试显示了预期的应力与应变行为，其中没有停留时间的循环显示出较低的磁滞面积值，从该值可以计算出应变循环中消耗的能量。消耗的能量值的增加归因于停留时间的插入，但重要的是要注意，对于包含120 s和300 s停留时间的测试，它们在消耗的能量之间并未显示出显着差异，显示出的饱和张力效应不会促进更大的非弹性应变。具有停留时间的循环机械疲劳应力和低变形率导致二次碳化物Cr大量析出₂₃ C ₆铬合金增加了不锈钢位错滑移的固有性能，是导致动态恢复现象的因素。对单调断裂试样和疲劳试验后的试样进行的分形分析表明，该材料在晶间区域内易于断裂。