Effect of Process Parameters on Defects, Melt Pool Shape, Microstructure, and Tensile Behavior of 316L Stainless Steel Produced by Selective Laser Melting
来源期刊：Acta Metallurgica Sinica2021年第4期
论文作者：Hua-Zhen Jiang Zheng-Yang Li Tao Feng Peng-Yue Wu Qi-Sheng Chen Yun-Long Feng Long-Fei Chen Jing-Yu Hou He-Jian Xu
文章页码：495 - 510
摘 要：Previous studies have revealed that laser power and energy density are significant factors affecting the quality of parts manufactured by selective laser melting（SLM）.The normalized equivalent density E0* and dimensionless laser power q*,which can be regarded as a progress on the understanding of the corresponding dimensional quantities,are adopted in this study to examine the defects,melt pool shape,and primary dendrite spacing of the SLM-manufactured 316 L stainless steel,because it reflects the combined effect of process parameters and material features.It is found that the number of large defects decreases with increasing E0* due to enough heat input during the SLM process,but it will show an increasing trend when excessive heat input（i.e.,utilizing a high E0*） is imported into the powder bed.The q* plays an important role in controlling maximum temperature rising in the SLM process,and in turn,it affects the number of large defects.A large q* value results in a low value of absolute frequency of large defects,whereas a maximum value of absolute frequency of large defects is achieved at a low q* even if E0* is very high.The density of the built parts is greater at a higher q* when E0* remains constant.Increasing the melt pool depth at relatively low value of E0* enhances the relative density of the parts.A narrow,deep melt pool can be easily generated at a high q* when E0* is sumciently high,but it may increase melt pool instability and cause keyhole defects.It is revealed that a low E0* can lead to a high cooling rate,which results in a refined primary dendrite spacing.Relatively low E0* is emphasized in selecting the process parameters for the tensile test sample fabrication.It shows that excellent tensile properties,namely ultimate tensile strength,yield strength,and elongation to failure of773 MPa,584 MPa,and 46%,respectively,can be achieved at a relatively low E0* without heat treatment.
Hua-Zhen Jiang1,2，Zheng-Yang Li2，Tao Feng3，Peng-Yue Wu3，Qi-Sheng Chen1,2，Yun-Long Feng3，Long-Fei Chen3，Jing-Yu Hou1,2，He-Jian Xu2
1. School of Engineering Science,University of Chinese Academy of Sciences2. Institute of Mechanics,Chinese Academy of Sciences3. Beijing E-Plus-3D Technology Co.,LTD
摘 要：Previous studies have revealed that laser power and energy density are significant factors affecting the quality of parts manufactured by selective laser melting（SLM）.The normalized equivalent density E0* and dimensionless laser power q*,which can be regarded as a progress on the understanding of the corresponding dimensional quantities,are adopted in this study to examine the defects,melt pool shape,and primary dendrite spacing of the SLM-manufactured 316 L stainless steel,because it reflects the combined effect of process parameters and material features.It is found that the number of large defects decreases with increasing E0* due to enough heat input during the SLM process,but it will show an increasing trend when excessive heat input（i.e.,utilizing a high E0*） is imported into the powder bed.The q* plays an important role in controlling maximum temperature rising in the SLM process,and in turn,it affects the number of large defects.A large q* value results in a low value of absolute frequency of large defects,whereas a maximum value of absolute frequency of large defects is achieved at a low q* even if E0* is very high.The density of the built parts is greater at a higher q* when E0* remains constant.Increasing the melt pool depth at relatively low value of E0* enhances the relative density of the parts.A narrow,deep melt pool can be easily generated at a high q* when E0* is sumciently high,but it may increase melt pool instability and cause keyhole defects.It is revealed that a low E0* can lead to a high cooling rate,which results in a refined primary dendrite spacing.Relatively low E0* is emphasized in selecting the process parameters for the tensile test sample fabrication.It shows that excellent tensile properties,namely ultimate tensile strength,yield strength,and elongation to failure of773 MPa,584 MPa,and 46%,respectively,can be achieved at a relatively low E0* without heat treatment.
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