Effects of post-weld heat treatment on the microstructure and mechanical properties of laser-welded NiTi/304SS joint with Ni filler
Effects of post-weld heat treatment on the microstructure and mechanical properties of laser-welded NiTi/304SS joint with Ni filler
复制标题
焊后热处理对NiTi/304SS激光焊接NiTi/304SS接头显微组织和力学性能的影响
DOI：
10.1016/j.msea.2019.138545
复制
发表时间：
2020-01-13
期刊：
影响因子：
6.4
通讯作者：
Li, Shuhan
中科院分区：
文献类型：
--
作者：
Chen, Yuhua;Sun, Songwei;Li, Shuhan
添加Ni作为填充材料是抑制NiTi/不锈钢(SS)激光焊接接头裂纹的有效方法之一，但NiTi/Ni界面处Ni3Ti的形成导致接头显微组织分布不均匀，限制了接头的抗拉强度。在这项研究中，对无缺陷的 NiTi/Ni/SS 接头进行了 650 摄氏度和 850 摄氏度的焊后热处理 (PWHT)，以提高其机械性能。随着 PWHT 温度的升高，在焊缝金属处观察到更多的 Ni3Ti。这种析出强化了焊缝金属，导致焊缝金属的平均硬度从375 HV0.2增加到493 HV0.2。由于焊后热处理后接头微观结构的均匀化，接头的抗拉强度得到提高。 850℃ PWHT 时接头平均强度最高达到 643 MPa，比焊态接头高约 2.12 倍。
Adding Ni as filler material is one of the effective methods to restrain the cracks in laser-welded joints of NiTi/ stainless steel (SS), while the formation of Ni3Ti at the NiTi/Ni interface result in uneven distribution of the microstructure of the joint, which limits tensile strength of the joint. In this study, post-weld heat treatment (PWHT) at 650 degrees C and 850 degrees C were applied on a defect-free NiTi/Ni/SS joint to improve its mechanical properties. As the PWHT temperature increases, more Ni3Ti was observed at the weld metal. This precipitation strengthened the weld metal, resulting in the average hardness of the weld metal increased from 375 HV0.2 to 493 HV0.2. Owing to the homogenization of microstructure of joints after PWHT, the tensile strength of the joint improved. The highest joint average strength reached 643 MPa at 850 degrees C PWHT, which is about 2.12 times higher than that of the as-welded joint.