304/Q245R爆炸复合板结合界面的退火组织和硬度

Annealing microstructure and hardness in bonded interface of 304 steel/Q245R steel composite plates by explosive welding

关键词:  爆炸焊接  基材  显微组织  纳米压痕仪

Key words:  explosive welding  base metal  microstructure  nano indenter

摘要:

针对304/Q245R爆炸焊接复合板,采用扫描电镜(SEM)和纳米压痕仪研究了消应力退火后基材侧结合界面中珠光体(P)和铁素体(F)形态的演变及对硬度的影响. 结果表明,细晶区为再结晶形成的直径为1 μm的等轴晶粒,原珠光体位置形成的等轴晶粒中,铁素体亚晶尺寸小于100 nm,亚晶界由不连续的球化渗碳体和连续分布的碳原子构成;纤维区中珠光体破碎部位分别发生渗碳体球化和铁素体亚晶析出,部分未破碎的层状珠光体发生时效软化;扭转晶粒区少量破碎的珠光体发生渗碳体球化和铁素体亚晶析出,大量未破碎的层状珠光体区域则发生时效硬化;结合界面中铁素体和珠光体的硬度依据各区域软化或硬化的机制而不同.

Abstract:

The pearlite (P) and ferrite (F) morphology evolution and its influence on the hardness in the interface, after stress relief annealing, on substrate side of composite plate joint between 304 steel and Q245R steel by explosive welding were investigated using scanning electron microscope (SEM) and nano indentation. The results show that the diameter of recrystallized equiaxed grain was 1 μm in fine grain zone, the size of ferrite subgrain among equiaxed grains formed in the original pearlite position was less than 100 nm. The subgrain boundary consisted of discontinuous spheroidized cementite and continuously distributed carbon atom. Spheroidization of cementite and precipitation of ferrite subgrain occurred in broken pearlites in fiber zone, and some unbroken lamellar pearlites age softened. In distorted grain zone, spheroidization of cementite and precipitation of ferrite subgrain occurred in a few broken pearlites, but other unbroken lamellar pearlites age hardened. At bonded interface, the hardness of ferrite and pearlite changed depending on the softening or hardening mechanisms in different regions.