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通过对不同淬火、回火工艺处理后的F550海洋平台用钢的力学性能、断口形貌、微观组织等进行分析,探讨了淬火、回火工艺参数对钢板性能及组织的影响。结果表明,淬火温度越高,组织晶粒越细小;随回火温度的升高,组织粗化,位错密度减少,钢板强度降低,塑性和韧性提高。16mm厚F550钢板最佳调质工艺为:880℃×120min淬火,630℃×220min回火。调质处理后钢板组织为粒状贝氏体+少量板条铁素体,屈服强度580MPa,抗拉强度660MPa,断后伸长率23%,-60℃冲击功稳定在210J以上。
The mechanical properties, fracture morphology and microstructure of F550 offshore platform steel treated by different quenching and tempering processes were analyzed. The effects of quenching and tempering process parameters on the properties and microstructure of the steel plate were discussed. The results show that the higher the quenching temperature, the smaller the grain size of the microstructure. With the increase of tempering temperature, the microstructure becomes coarse, the dislocation density decreases, the strength of the steel sheet decreases, and the plasticity and toughness increase. 16mm thick F550 optimal quenching process for the steel: 880 ℃ × 120min quenching, 630 ℃ × 220min tempering. After quenching and tempering, the microstructure of the steel plate is granular bainite + small amount of lath ferrite. The yield strength is 580MPa, the tensile strength is 660MPa, the elongation at break is 23%, and the impact energy at 60 ℃ is stabilized at 210J or above.