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采用光学显微镜、扫描电镜及X射线衍射XRD,对比分析了S890钢水淬、油淬、空淬、550℃和420℃等温淬火不同工艺处理后的淬火、以及600℃回火组织;并测试了硬度和冲击性能。结果表明,水淬试样得到全马氏体组织,回火后硬度32.5 HRC,-40℃低温冲击功118 J;经过油淬和550℃等温淬火试样,马氏体组织中混有贝氏体,硬度略低但韧性显著下降;空淬和420℃等温淬火得到全贝氏体组织,韧性最低。分析表明,S890钢中马氏体在回火过程中,板条上析出的大量弥散的纳米级碳化物使S890钢具有优良的强韧性;而贝氏体铁素体和碳化物的结构、位向、形态等决定了其贝氏体的本征脆性。
The microstructures of S890 steel after quenching by water quenching, oil quenching, air quenching, isothermal quenching at 550 ℃ and 420 ℃, and tempering at 600 ℃ were analyzed by optical microscope, scanning electron microscopy and X-ray diffraction (XRD) And impact performance. The results show that the water-quenched specimens are all-martensitic. After tempering, the hardness is 32.5 HRC and the impact energy at -40 ℃ is 118 J. After oil quenching and austempering at 550 ℃, martensite is mixed with Bayesian Body, hardness slightly lower but significantly decreased toughness; empty quenching and isothermal quenching at 420 ℃ bainite tissue obtained, the lowest toughness. The analysis shows that in the tempering process of S890 steel, a large amount of dispersed nano-scale carbide precipitated on the slab makes S890 steel excellent in toughness. However, the structure of bainite ferrite and carbide To determine the shape of bainite and its inherent fragility.