利用焊接热模拟技术和透射电子显微镜对大线能量低焊接裂纹敏感性钢的焊接热影响区(HAZ)组织及晶内铁素体 (IGF)的形核机理进行了试验研究。通过对大线能量焊接 (10 0kJ/cm)条件下HAZ中IGF精细组织分析 ,认为IGF非均匀形核核心主要为富含MnS和Si元素的Ti2 O3复合粒子。 The heat-affected zone (HAZ) structure and the nucleation mechanism of intragranular ferrite (IGF) in steels with high heat input and welding crack susceptibility were studied by means of welding thermal simulation and transmission electron microscopy. Through the analysis of IGF in the HAZ under the condition of large wire energy welding (10 0 kJ / cm), it is considered that the heterogeneous nuclei of IGF mainly consist of Ti 2 O 3 composite particles rich in MnS and Si.