加热温度对600 MPa级高强钢筋组织及性能的影响

 为了推进高强钢筋工业应用,以Nb-V复合微合金化600 MPa级高强钢筋为研究对象,采用高温激光共聚焦显微镜研究了加热温度对晶粒长大规律的影响,并进行了工业试制。结果表明,随着加热温度升高、保温时间延长,奥氏体晶粒尺寸增大;加热温度从1 180提高至1 270 ℃,保温60 min,奥氏体平均晶粒尺寸从58.7提高至85.1 μm。工业试制中,加热温度由1 200提高至1 270 ℃,珠光体比例增加,珠光体团尺寸增大,屈服强度和抗拉强度升高,伸长率下降,拉伸断口形貌由韧性断裂转变为准解理脆性断裂;当加热温度为1 200~1 250 ℃时,屈服强度为640~659 MPa,抗拉强度为823~846 MPa,强屈比为1.28~1.30,断后伸长率为16.6%~19.2%,最大力伸长率为10.6%~13.0%。

Effect of heating temperature on microstructure and properties of 600 MPa grade high strength steel rebars

In order to achieve the industrial application of high strength steel rebars,Nb-V microalloyed 600 MPa grade steel rebars were set as studied object,effect of heating temperature on grain growth was studied by confocal laser scanning high-temperature microscope,and plant trial was conducted. The result shows that increasing heating temperature leads to increasing austenite grains.When the heating temperature changes from 1 180 ℃ to 1 270 ℃ and the soaking time is 60 min,the average austenite grain size improves from 58.7 μm to 85.1 μm. When the heating temperature is improved to 1 270 ℃,the average austenite grain size increases to 77.8 μm. In plant trial,with the heating temperature increases from 1 200 ℃ to 1 270 ℃,the proportion of pearlite and the size of the pearlite colony increases,the tensile fracture morphology changes from ductile fracture to quasi-cleavage brittle fracture. While heating at 1 200-1 250 ℃ can produce a steel rebars with a yield strength of 640-659 MPa,a tensile strength of 823-846 MPa,a yield ratio of 1.28-1.30,a elongation rate of 16.6%-19.2%,a maximum force elongation of 10.6%-13.0%.