轧制工艺对Q345E钢棒材组织性能的影响

Effect of Rolling Process on Microstructure and Mechanical Properties of Q345E Steel Rod

使用常规轧制与低温控制轧制工艺轧制出φ80mm的Q345E棒材,采用OM、SEM、EBSD和TEM对其组织与性能进行了研究。结果表明:采用常规轧制工艺的Q345E棒材的屈服强度与抗拉强度分别为387、550MPa,-40℃冲击功仅为15J;而采用低温控制轧制工艺的屈服强度与抗拉强度分别为388、517MPa,-40℃冲击功达151J。控制轧制工艺获得的铁素体+珠光体组织更为细小,具有较小的晶粒尺寸,有利于提高其低温冲击韧性;常规轧制工艺下铁素体中析出大量细小弥散的第二相,提高了材料的抗拉强度,同时恶化了低温冲击韧性。

The Q345E rod of φ80 mm was rolled by conventional rolling and low temperature controlled rolling process.The microstructure and properties were studied by OM, SEM, EBSD and TEM. The results show that the yield strength and tensile strength of Q345E bar by conventional rolling process are 387 and 550 MPa respectively, and the impact power at -40℃ is only 15 J. The yield strength and tensile strength of low temperature controlled rolling process are 388 and 517 MPa respectively, and the impact power of -40℃ is 151 J. The microstructure of ferrite +pearlite obtained by controlled rolling process is smaller and it has smaller grain size, which is beneficial to improve its low temperature impact toughness. A large number of fine and dispersed second phases are precipitated in ferrite under conventional rolling process, which improves the tensile strength of the material and deteriorates the low temperature impact toughness.