不同工艺低碳Nb-B贝氏体钢组织性能

对一种不添加其他微合金元素的低碳Nb-B微合金贝氏体钢在不同工艺的组织和力学性能进行研究.结果表明,终轧温度为850℃,冷却速度10℃/s左右,终冷温度560℃时,实验钢的屈服强度和抗拉强度分别为495和720MPa,-20℃冲击功和延伸率分别为159 J和23%,实验钢组织为粒状贝氏体和准多边形铁素体;终冷温度降至480℃,实验钢组织为粒状贝氏体,屈服强度和-20℃冲击功分别提高51 MPa和93 J;终轧温度降至810℃时,屈服强度相对增加24MPa;冷却速度增大到25℃/s,组织为粒状贝氏体、少量的针状铁素体和板条贝氏体,屈服强度和抗拉强度分别为655和777 MPa,而-20℃冲击功和...

Microstructures and Mechanical Properties of Low Carbon Nb- B Bainitic Steel with Different Processing

The microstructures and mechanical properties of a low carbon Mn-Nb-B bainitic steel were investigated.The results revealed that when the finish rolling temperature is 850 ℃,the cooling rate is about 10 ℃/s and the stop cooling temperature is 560 ℃.The microstructure of tested steel is quasi-polygonal ferrite and granular bainite.The yield strength,tensile strength,impact energy(-20 ℃) and elongation are 495 and 720 MPa,159 J,23%,respectively.As the stop cooling temperature is decreased to 480 ℃,the yield strength and tensile strength are increased 51 MPa and 93 J respectively.The yield strength is increased 24 MPa when the finish rolling temperature is decreased to 810 ℃.When the cooling rate is increased to 25 ℃/s,the microstructure is composed of granular bainite,acicular ferrite and lath bainite.The yield strength,tensile strength,impact energy(-20 ℃),elongation are 655 and 777 MPa,226 J,20%,respectively.The substructure can be refined by accelerated cooling.The strength of tested steel can be increased observably through the substructure strengthing and the existence of lath bainite.