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工程机械用1000MPa级高强钢焊后需进行去应力退火处理,而可进行焊后热处理的焊缝金属是保证接头性能的关键。利用透射电镜、场发射高分辨透镜和扫描电镜及EDS等手段对铜含量(质量分数)为0.41%、0.89%和1.14%的焊缝金属进行了显微组织及力学性能分析。研究结果表明,三种焊缝热处理前后均为板条马氏体和板条贝氏体组织,其中含铜0.89%和1.14%的焊缝热处理后在板条上弥散析出大量的ε-Cu相。焊态下,焊缝的强韧性匹配较好;去应力退火后,焊缝的屈服强度升高,而冲击韧性大幅降低。铜对焊缝热处理前后的力学性能影响较大,可使焊缝产生时效脆化。
The 1000MPa high strength steel used for construction machinery needs to be stress relief annealed before welding, and the weld metal which can be heat treated after welding is the key to ensure the joint performance. The microstructure and mechanical properties of the weld metal with 0.41%, 0.89% and 1.14% Cu content were analyzed by TEM, field emission high resolution lens, scanning electron microscopy and EDS. The results show that the three kinds of weld before and after the heat treatment are lath martensite and lath bainite, in which 0.89% copper and 1.14% of the weld heat treatment after dispersion in the slab on a large number of ε-Cu phase . In the as-welded state, the strength and toughness of the weld match well; after the stress-relief annealing, the yield strength of the weld increases, while the impact toughness decreases drastically. Copper on the weld heat treatment before and after the mechanical properties of a greater impact, can make the weld aging embrittlement.