表面技术2025，Vol.54Issue(5)：167-175,9.DOI:10.16490/j.cnki.issn.1001-3660.2025.05.013
Si含量对316L不锈钢激光熔覆层凝固行为和显微组织的影响
Effects of Si Content on Solidification Behavior and Microstructure of 316L SS Laser Cladding Layer
摘要
Abstract
In this study,the influence of different mass fractions of silicon(Si)on the solidification microstructure of 316L stainless steel during laser cladding process was investigated in details.A laser cladding system consisting of a LDF400-2000 fiber-coupled semiconductor laser and an ABB manipulator was utilized to deposit a cladding layer containing 0.8%and 1.6%Si on an 316L substrate.Multiple characterization techniques,such as optical microscopy,scanning electron microscopy(SEM),electron backscatter diffraction(EBSD),transmission electron microscopy(TEM),and Vickers hardness testing were employed to assess the microstructure,formation mechanism,grain orientation,texture,and microhardness of the cladding layer both in the scanning direction(SD)and the tangential direction(TD). The results revealed clear differences in grain growth patterns depending on the Si content.In the SD direction,the cladding layer with 0.8%-Si displayed a columnar grain structure,with grains growing perpendicularly from the interface between the substrate and the cladding layer.The top regions of these grains exhibited a cellular morphology.For the 1.6%-Si cladding layer,although the grain growth pattern was still columnar at the bottom parts,the crystal orientation became more random,particularly in the top regions of the cladding.This indicated that higher Si content tended to reduce the alignment of grains,leading to more isotropic properties.In the TD direction,grain orientation was more strongly affected by the Si content.For the 0.8%-Si cladding layer,grain growth followed an epitaxial growth pattern with a strong<100>preferential orientation,meaning the grains continued growing in alignment with the crystallographic orientation of the substrate.This epitaxial growth was less prominent in the 1.6%-Si cladding layer,where the grains were influenced more by the thermal gradient created during solidification,resulting in a<111>preferential growth direction.This shift in grain orientation was significant because it suggested that higher Si content changed the way heat dissipated through the material during solidification,leading to a different grain nucleation mechanism. Another significant difference between the two Si content levels was in the proportion of low-angle grain boundaries(LAGBs).For the 1.6%-Si cladding layer,more than 50%of the grain boundaries were low-angle boundaries,which indicated that higher Si content favored the formation of grains that were more closely aligned in orientation but had subtle misalignments.This resulted in an overall more textured microstructure compared with the 0.8%-Si cladding layer.Low-angle grain boundaries were important because they could impede dislocation motion,contributing to increased strength.Moreover,submicro particles were observed within the grains of the 1.6%-Si cladding layer,especially in the grain interior.TEM observations confirmed that a large number of dislocations presented within the central regions of grains,which further supported the increase in strength observed with increasing Si content.Microhardness testing results demonstrated a significant increase in hardness with increasing Si content.The 0.8%-Si cladding layer had a hardness of 199.7HV0.3,while the 1.6%-Si cladding layer exhibited a higher hardness of 212.2HV0.3.This hardness increase could be attributed to the refinement of the grain structure and the change in the solidification mode.As the Si content increased,the nucleation rate also increased,which promoted the formation of finer grains.The solidification structure transitioned from coarse columnar dendrites to finer cellular grains,which helped improve the mechanical properties,especially hardness. In summary,the addition of Si to 316L stainless steel during laser cladding significantly affects the solidification behavior and microstructure.These microstructural changes result in improved mechanical properties,particularly in terms of hardness and strength.关键词
激光熔覆/Si元素/316L/凝固组织/晶粒细化Key words
laser cladding/Si element/316L/solidification structure/grain refinement分类
矿业与冶金引用本文复制引用
古青,包海斌,王永强,冯敏敏,董刚,尤涵潇,杨高林,姚建华..Si含量对316L不锈钢激光熔覆层凝固行为和显微组织的影响[J].表面技术,2025,54(5):167-175,9.基金项目
国家自然科学基金(52035014) （52035014）
浙江省公益技术应用研究项目(LGG22E050036) （LGG22E050036）
舟山科技计划(2023C13011) National Natural Science Foundation of China(52035014) （2023C13011）
Public Welfare Project of Zhejiang Province(LGG22E050036) （LGG22E050036）
Zhoushan Science and Technology Plan Project(2023C13011) （2023C13011）
