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将C-Mn钢分别加热至760、800和850℃均热120 s后,快速冷却至460℃以模拟热镀锌工艺。退火后对试验钢进行预应变(2%)和烘烤处理(170℃×20 min)以测量其烘烤硬化(BH)值。通过金相显微镜、扫描电镜、拉伸等技术,研究了均热温度对590 MPa级热镀锌双相钢微观组织、力学性能和烘烤硬化性能的影响。结果表明,在760~850℃范围内退火时,试验钢中未观察到贝氏体组织,微观组织由铁素体和马氏体组成,抗拉强度均达到590 MPa以上。热镀锌双相钢在800℃退火时,具有优良的综合力学性能,其屈服强度为295 MPa,抗拉强度为606 MPa,伸长率为32.1%,强塑积为19 450 MPa·%。随着均热温度提高,BH值呈先增加后降低趋势;均热温度为800℃时,BH达最大值81 MPa。
The C-Mn steels were heated to 760, 800 and 850 ° C, respectively, for 120 s, then rapidly cooled to 460 ° C to simulate the hot-dip galvanizing process. After annealing, the test steels were pre-strained (2%) and baked (170 ° C x 20 min) to measure the bake-hardenability (BH) value. The effects of soaking temperature on the microstructure, mechanical properties and bake hardenability of 590 MPa hot-dip galvanized duplex steel were studied by means of metallographic microscope, scanning electron microscope and tensile test. The results showed that no bainite microstructure was observed in the test steel when annealed in the range of 760-850 ℃. The microstructure was composed of ferrite and martensite, and the tensile strength reached 590 MPa. Hot dip galvanized duplex steel annealed at 800 ℃ has excellent mechanical properties. The yield strength is 295 MPa, the tensile strength is 606 MPa, the elongation is 32.1% and the strong plastic product is 19 450 MPa ·%. With the increase of soaking temperature, the BH value first increases and then decreases. When the soaking temperature is 800 ℃, BH reaches 81 MPa.