Selective laser melting (SLM) and laser metal deposition (LMD) are the two methods of laser additive manufacturing (LAM), which are distinguished by the different powder feeding methods. In this paper, the temperature field (temperature distribution, cooling rate, temperature gradient and dimensions of molten pool), appearance and microstructure (grain shape and size, and phase composition) of the LMDed 304 austenitic stainless steel (SS304) specimen are compared with those of the SLMed SS304 specimen published in the previous literature. The results show that the LMDed SS304 specimen has the similar temperature field trend with the SLMed SS304 specimen. The differences for temperature field obtained by the finite element models (FEMs) are that LMD produces the higher temperature and dimensions of molten pool, but the lower cooling rate and temperature gradient. The appearances of the LMDed and SLMed specimens are compared. Since the molten pool during LMD is larger, the surface roughness of the LMDed SS304 specimen is higher than that of the SLMed SS304 specimen. Due to the different cooling rates, the LMDed SS304 specimen has the different microstructure from the SLMed SS304 specimen. The SLMed and LMDed specimens have the similar columnar grain shape, but the grain size of the LMDed specimen is larger. The microstructure of LMDed SS304 specimen is composed of two phases, which are austenite phase and small amount of ferrite phase. But the SLMed specimen has the full austenite phase. The differences between SLM and LMD are also studied in this paper.

选择性激光熔化（SLM）和激光金属沉积（LMD）是激光增材制造（LAM）的两种方法，它们的区别在于送粉方式不同。本文将LMDed 304奥氏体不锈钢（SS304）试样的温度场（温度分布，冷却速率，温度梯度和熔池尺寸），外观和微观结构（晶粒形状和尺寸以及相组成）与先前文献中发表的SLMed SS304标本的材料。结果表明，LMDed SS304标本具有与SLMed SS304标本相似的温度场趋势。通过有限元模型（FEM）获得的温度场的差异在于LMD产生了更高的温度和熔池尺寸，但冷却速度和温度梯度较低。比较了LMDed和SLMed标本的外观。由于LMD期间的熔池较大，因此LMDed SS304试样的表面粗糙度高于SLMed SS304试样的表面粗糙度。由于冷却速率不同，LMDed SS304样品的显微结构与SLMed SS304样品不同。SLMed和LMDed标本具有相似的柱状晶粒形状，但LMDed标本的晶粒尺寸较大。LMDed SS304试样的显微组织由两相组成，即奥氏体相和少量铁素体相。但是，SLMed试样具有完整的奥氏体相。本文还研究了SLM和LMD之间的差异。由于LMD期间的熔池较大，因此LMDed SS304试样的表面粗糙度高于SLMed SS304试样的表面粗糙度。由于冷却速率不同，LMDed SS304样品的显微结构与SLMed SS304样品不同。SLMed和LMDed标本具有相似的柱状晶粒形状，但LMDed标本的晶粒尺寸较大。LMDed SS304试样的显微组织由两相组成，即奥氏体相和少量铁素体相。但是，SLMed试样具有完整的奥氏体相。本文还研究了SLM和LMD之间的差异。由于LMD期间的熔池较大，因此LMDed SS304试样的表面粗糙度高于SLMed SS304试样的表面粗糙度。由于冷却速率不同，LMDed SS304样品的显微结构与SLMed SS304样品不同。SLMed和LMDed标本具有相似的柱状晶粒形状，但LMDed标本的晶粒尺寸较大。LMDed SS304试样的显微组织由两相组成，即奥氏体相和少量铁素体相。但是，SLMed试样具有完整的奥氏体相。本文还研究了SLM和LMD之间的差异。LMDed SS304标本具有与SLMed SS304标本不同的微观结构。SLMed和LMDed标本具有相似的柱状晶粒形状，但LMDed标本的晶粒尺寸较大。LMDed SS304试样的显微组织由两相组成，即奥氏体相和少量铁素体相。但是，SLMed试样具有完整的奥氏体相。本文还研究了SLM和LMD之间的差异。LMDed SS304标本具有与SLMed SS304标本不同的微观结构。SLMed和LMDed标本具有相似的柱状晶粒形状，但LMDed标本的晶粒尺寸较大。LMDed SS304试样的显微组织由两相组成，即奥氏体相和少量铁素体相。但是，SLMed试样具有完整的奥氏体相。本文还研究了SLM和LMD之间的差异。