两相区退火温度对含铜贝氏体/铁素体复相钢组织和性能的影响

Influence of intercritical annealing temperature on microstructure and mechanical properties of Cu bearing bainite/ferrite multiphase steel

借助SEM、XRD、TEM、EPMA、室温拉伸等试验手段,采用IQ＆PB（两相区退火-贝氏体区淬火碳配分）热处理工艺,针对两相区退火温度对含铜贝氏体/铁素体复相钢组织和性能的影响进行研究。结果表明,两相区退火温度升高,铁素体所占体积分数减少,板条状贝氏体含量增加;试验用钢的抗拉强度逐渐升高,而伸长率则不断下降。室温组织中残留奥氏体含量,随退火温度升高呈先增加后减少的趋势变化。790℃退火处理,拉伸形变过程,应变后期加工硬化指数n值较高,持续加工硬化能力明显,断口处裂纹尖端钝化,强塑积可达28.06 GPa·%。

Influence of intercritical annealing temperature on the microstructure and mechanical properties of a Cu bearing bainite/ferrite multiphase steel under the treatment of IQPB process were studied by SEM,XRD,TEM,EPMA and room-temperature tensile test. The results show that when the intercritical annealing temperature increases,the volume fraction of ferrite reduces and the content of the lathy bainite increases,and the tensile strength of the experimental steel gradually increases,while the elongation decreases. With the increase of annealing temperature,the content of retained austenite increases first then reduces. When annealing treatment temperature is 790 ℃,the work hardening exponent is higher in the post-strain process,and the continuous working hardening capacity is obvious. The crack tip of the tensile fracture is passivated,and the product of strength and elongation can reach 28. 06 GPa·%.