Plotkowski A, Saleeby K, Fancher C M, Haley J, Madireddy G, An K, Kannan R, Feldhausen T, Lee Y, Yu D, Leach C, Vaughan J, Babu S S
Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
Manufacturing Science Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
Nat Commun. 2023 Aug 16;14(1):4950. doi: 10.1038/s41467-023-40456-x.
Residual stresses affect the performance and reliability of most manufactured goods and are prevalent in casting, welding, and additive manufacturing (AM, 3D printing). Residual stresses are associated with plastic strain gradients accrued due to transient thermal stress. Complex thermal conditions in AM produce similarly complex residual stress patterns. However, measuring real-time effects of processing on stress evolution is not possible with conventional techniques. Here we use operando neutron diffraction to characterize transient phase transformations and lattice strain evolution during AM of a low-temperature transformation steel. Combining diffraction, infrared and simulation data reveals that elastic and plastic strain distributions are controlled by motion of the face-centered cubic and body-centered cubic phase boundary. Our results provide a new pathway to design residual stress states and property distributions within additively manufactured components. These findings will enable control of residual stress distributions for advantages such as improved fatigue life or resistance to stress-corrosion cracking.
残余应力会影响大多数制成品的性能和可靠性，并且在铸造、焊接和增材制造（AM，3D打印）中普遍存在。残余应力与因瞬态热应力而累积的塑性应变梯度相关。增材制造中复杂的热条件会产生同样复杂的残余应力模式。然而，用传统技术无法测量加工过程对应力演变的实时影响。在此，我们使用原位中子衍射来表征低温转变钢增材制造过程中的瞬态相变和晶格应变演变。结合衍射、红外和模拟数据表明，弹性和塑性应变分布受面心立方和体心立方相界运动的控制。我们的结果为设计增材制造部件内的残余应力状态和性能分布提供了一条新途径。这些发现将有助于控制残余应力分布，以获得诸如提高疲劳寿命或抗应力腐蚀开裂等优势。
