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研究了空冷条件下,海洋平台用钢中的不同镍含量(wNi=0.2%,0.53%,0.8%、1.11%)对其显微组织及力学性能的影响。结果表明,当镍含量较低时,所得显微组织为铁素体和马氏体,晶粒尺寸粗大;随着镍含量的增加,多边形铁素体量降低,针状铁素体量提高,M/A岛更加细小弥散,析出相由相间析出向均匀弥散析出转变,析出粒子尺寸降低;试验钢的屈服强度和抗拉强度随镍含量增加而单调增加,伸长率先增加后降低,而韧脆转变温度先降低后增加,当wNi=0.5%～0.83%时,试验钢具有最佳的低温韧性。
The effects of different nickel contents (wNi = 0.2%, 0.53%, 0.8%, 1.11%) on the microstructure and mechanical properties of steel for offshore platform were investigated under air cooling. The results show that when the content of nickel is low, the obtained microstructure is ferrite and martensite, and the grain size is coarse. With the increase of nickel content, the amount of polygonal ferrite decreases, the amount of acicular ferrite increases, M / A island is more finely dispersed, the precipitates change from precipitates to precipitates uniformly, and the precipitated particles decrease in size. The yield strength and tensile strength of test steel increase monotonically with the increase of nickel content, while the elongation increases first and then decreases, while the toughness increases The brittle transition temperature first decreases and then increases. When wNi = 0.5% ~ 0.83%, the test steel has the best low temperature toughness.