Studies conducted in recent years have shown that the ultimate load-bearing and deformation capacity of weldments manufactured from ultra-high-strength steel is often impacted by the heat-affected zone. Thus, to assess the strength properties of these welds, in addition to the base material properties and weld metal, the heat-affected zone's mechanical properties must be analyzed. In this study, a discretization and material parameter characterization are conducted for friction-welded joints in direct-quenched armor steel. The discretization is based on the microstructural analysis and hardness measurements conducted for the weld. After data analysis and considering the practical aspects, such as computational factors and other resources, a model with six different material parameter regions for the heat-affected zone was chosen. For all regions, the quasi-static part of the Johnson–Cook constitutive model was used. Three of the most distant zones measured from the weld interface were subcritically heated during the friction welding. The material parameters for these zones were identified using thermal simulations, tensile experiments, and numerical optimization, whereas the material parameters for the three remaining zones were identified using tensile experiments combined with numerical models and optimization routines. The generated model was successfully used in the fracture assessment of four friction-welded specimens with different degrees of metallurgical constraint. The effect of the subcritically-heated zones on the model's accuracy was studied. Neglecting the subcritical zone within the models caused an overestimation of the joint's tensile strength. Also, three alternative numerical models with different discretization's were generated and used in the fracture assessment. The validity of the generated models was tested by applying the HAZ model to models of tensile test specimens with different degrees of metallurgical constraint. The three alternative models could not correctly assess the fracture. In addition, the different models produced differing stress-strain curves.

近年来进行的研究表明，由超高强度钢制成的焊件的最终承重和变形能力通常受热影响区的影响。因此，为了评估这些焊缝的强度特性，除了基材特性和焊缝金属外，还必须分析热影响区的机械特性。在这项研究中，对直接淬火铠装钢中的摩擦焊接接头进行了离散化和材料参数表征。离散化基于对焊缝进行的显微组织分析和硬度测量。经过数据分析并考虑了实际因素，例如计算因素和其他资源，为热影响区选择了具有六个不同材料参数区域的模型。对于所有区域，都使用了Johnson-Cook本构模型的准静态部分。在摩擦焊接过程中，距离焊接界面最远的三个区域被亚临界加热。这些区域的材料参数是使用热模拟，拉伸实验和数值优化来确定的，而其余三个区域的材料参数是通过使用拉伸实验，数值模型和优化例程来确定的。所生成的模型已成功用于四个冶金焊接程度不同的摩擦焊接试样的断裂评估。研究了亚临界加热区对模型精度的影响。忽略模型中的亚临界区会导致对接头抗拉强度的高估。同样，生成了三个具有不同离散度的替代数值模型，并将其用于裂缝评估。通过将HAZ模型应用于具有不同冶金约束度的拉伸试样的模型来测试所生成模型的有效性。这三种替代模型无法正确评估骨折。另外，不同的模型产生不同的应力-应变曲线。