Binder Jetting-Metal Additive Manufacturing (BJ-MAM) is a powder bed-based additive manufacturing technology which deposits liquid binder droplets to join powder particles to form complex shaped structures (i.e., green parts). As the printing process is done around room temperature, BJ-MAM is largely immune to the distortion and cracking issues that can be prevalent in melting based powder bed processes. However, a main issue for BJ-MAM is the part shrinkage and distortion during high-temperature sintering. The densification and deformation behaviors during pressureless sintering of green parts printed by BJ-MAM were studied in this paper. Experimentally, cantilever- and bridge-shaped coupons with varying beam lengths were printed using 316L stainless steel powder; these coupons produced different extents of deformation after sintering. Based on the existing modeling approaches in the powder metallurgy literature, a finite element model was developed incorporating an elastic-viscoplastic constitutive equation for computing both uniaxial equivalent creep strain and volumetric swelling strain. Two methods, a viscosity based and a power-law creep based, were further evaluated for calculating the uniaxial equivalent creep strain. Material property data used in the constitutive equation such as viscosity and creep parameters were collected from the literature, critically reviewed, and then inputted into the model. Other salient features of the model included thermal-mechanical property data that were dependent on both relative density and temperature as well as frictional contact between the part surface and the furnace wall under gravitational load. The calculated quantities such as shrinkage, final relative density, and deformed shapes were compared with the respective experimental data across different part geometries.

粘合剂喷射金属增材制造 (BJ-MAM) 是一种基于粉末床的增材制造技术，它沉积液态粘合剂液滴以连接粉末颗粒以形成复杂形状的结构（即生坯部件）。由于打印过程是在室温下完成的，BJ-MAM 在很大程度上不受基于熔化的粉末床过程中可能普遍存在的变形和开裂问题的影响。然而，BJ-MAM 的一个主要问题是高温烧结过程中的零件收缩和变形。本文研究了 BJ-MAM 打印的生坯无压烧结过程中的致密化和变形行为。实验中，使用 316L 不锈钢粉末印刷具有不同光束长度的悬臂和桥形试样；这些试样在烧结后产生不同程度的变形。基于粉末冶金文献中现有的建模方法，开发了一种有限元模型，其中包含用于计算单轴等效蠕变应变和体积膨胀应变的弹-粘塑性本构方程。进一步评估了两种方法，即基于粘度的方法和基于幂律蠕变的方法，用于计算单轴等效蠕变应变。本构方程中使用的材料特性数据，如粘度和蠕变参数，均从文献中收集，经过严格审查，然后输入到模型中。该模型的其他显着特征包括热机械性能数据，这些数据取决于相对密度和温度以及重力载荷下零件表面和炉壁之间的摩擦接触。