大规格系泊链焊口冲击不稳定原因分析

Analysis of the causes of unstable impact at the welded joints of large-sized mooring chains

国内某锚链厂进行R3S系泊链加工后,检测发现链环的环背位置的性能可以满足船级社要求,但是焊口位置冲击值存在波动,有个别样品未达到冲击值要求。针对用户提供的焊口和环背试样进行了实验室分析,发现焊口位置主要为贝氏体组织,贝氏体晶粒内部和晶界均存在较大的碳化物,碳化物呈条状,尺寸超过2μm,同时还发现晶粒有长大现象。初步推断焊口位置冲击值偏低是因为大尺寸的条状碳化物在晶界分布,降低了晶界结合力,造成了冲击韧性偏低,此外焊口位置出现了尺寸较大的晶粒,对冲击韧性也产生不利影响。

Following the processing of R3S mooring chains by a domestic anchor chain factory,it was found through testing that the performance at the back of the chain link meets the requirements of the classification society.However,there were fluctuations in the impact toughness values at the weld position,with some samples failing to meet the required standards.Laboratory analysis of the provided weld and ring-back samples revealed the presence of strip-like carbides exceeding 2μm in size at the weld position.The weld position was predominantly composed of bainite,featuring large carbides both within the grains and at the grain boundaries.Additionally,evidence of grain growth was observed.It is hypothesized that the low impact toughness at the weld position can be attributed to the distribution of large-sized strip-like carbides at the grain boundary,which reduces grain boundary cohesion and impact toughness.Furthermore,the presence of larger grains at the weld position also negatively affects the impact toughness.