热处理对增材制造贝氏体钢组织及性能的影响

Effect of Heat Treatment on Microstructures and Properties of Wire and Arc Additive-Manufactured Bainite Steel

针对金属电弧增材制造过程热循环在线控制困难,导致成形组织不均、力学性能低下的问题,以辙叉用贝氏体钢为成形材料,研究了不同整体后热处理工艺对其电弧增材制造试样组织及性能的影响,并对热处理工艺进行了优化.研究结果表明:去应力退火后的电弧增材制造试样力学性能较差,且存在各向异性,经290℃等温淬火与280℃回火处理后,试样微观组织由回火索氏体转变为下贝氏体+回火马氏体,抗拉强度提升39%,屈服强度提升61%,断后延伸率提升29%,冲击韧性提升17%,硬度提升20%,且各向异性特征大大缓解,材料组织趋于均匀.

It is difficult to actively control the thermal cycle in wire and arc additive manufacturing（ WAAM）,resulting in uneven microstructures and poor mechanical properties. Therefore, an anisothermal quenching andtempering process for balnite steel deposition is presented herein. The microstructures and properties wereanalysed and optimised after a series of heat treatments. The results show that the annealed microstructureschange from tempered sorbite to lower bainite and tempered martensite after posttreatment, and the anisotropy isevidently weakened. After isothermal quenching at 290 ℃/oil cooling followed by tempering at 280 ℃/air cool-ing, the WAAM bainite steel shows more homogeneous microstructures and better mechanical properties, withincreases in the tensile strength, yield strength, elongation, impact toughness, and hardness, by 39%, 61%, 29%,17%, and 20%, respectively.