为研究Al-Si镀层对22MnB5钢激光焊接接头焊缝区显微组织、显微硬度和拉伸性能的影响，利用IPG YLR-6000型光纤激光器对1.5 mm厚有/无Al-Si镀层22MnB5钢进行激光焊接试验。结果表明：带Al-Si镀层样品焊缝和熔合区的显微组织均为板条马氏体+富铝δ铁素体，而去Al-Si镀层样品焊缝和熔合区的显微组织则为板条马氏体。其主要原因在于：在激光焊接过程中Al-Si镀层熔化并进入焊接熔池，由于Al元素在焊缝部分区域及熔合区处富集，导致高温δ铁素体稳定性提高，同时在激光快速冷却的条件下，部分δ铁素体无法发生包晶转变而被保留至室温。两种焊接接头的整体显微硬度分布规律一致，焊接接头硬度均高于母材，但是由于带Al-Si镀层样品焊缝中存在软相δ铁素体导致其硬度低于去除Al-Si镀层焊缝。尽管Al-Si镀层对于显微组织和显微硬度产生了影响，但是对于拉伸性能未见影响，两种焊接接头拉伸断裂位置均出现在母材区，且为典型的韧性断裂。
陈夏明
,
王晓南
,
孙茜
,
张敏
,
陈长军
,
邸洪双
. Al-Si镀层对22MnB5钢激光焊接接头组织和性能的影响[J]. 机械工程学报, 2018
, 54(6)
: 162
-167
.
DOI: 10.3901/JME.2018.06.162
In order to study the effect of Al-Si coating on the microstructure, microhardness and tensile properties of 22MnB5 laser welded joint, the IPG YLR-6000 fiber laser is used to fabricate 1.5 mm thick Al-Si coating 22MnB5 steel laser welding experiment. The results show that the fusion zone and fusion line of the Al-Si coating sample are lath martensite (LM) +Al-rich δ ferrite. However, the microstructure of the fusion zone and fusion line are LM which the Al-Si coating which is removed. The main reason is that the Al-Si coating melts and enters the welding pool during the laser welding process, and the stability of the high temperature δ ferrite increases due to the enrichment of the Al in the part of the fusion zone and the fusion line. At the same time under a rapid cooling conditions, some δ-ferrite can't occur peritectic transformation and it is retained to room temperature. The microhardness distribution of the two welded joints is consistent, and the microhardness of the welded joint is higher than that of the base metal. However, due to the presence of soft phase δ ferrite in the Al-Si coating, the hardness of the fusion zone is lower than that without Al-Si coating. Although the Al-Si coating has an effect on the microstructure and microhardness, it has no effect on the tensile properties. The tensile specimen of the two welded joints are both broken in the base metal, and it is a typical ductile fracture.
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