结构钢多相复合组织的微观参量对强塑性的影响

Effect of Micro Parameters of Multiphase Mixed Structure on Strength and Ductility in Structural Steel

研究了３０ＣｒＭｎＳｉＡ钢中马氏体（Ｍ）＋贝氏体铁素体（ＢＦ）＋铁素体（Ｆ）＋残留奥氏体（γＲ）多相复合组织形态、微观参量对强塑性的影响。研究结果表明，纤维状多相复合组织的屈服强度与Ｆ的强化状况及可动位错数量有关。极限强度主要受控于高强度相（Ｍ＋ＢＦ），尤其是Ｍ量及其强度，而塑性则与Ｆ纤维长度、γＲ量及各相强度差大小有关。采用１０５０℃预淬火＋７６０℃临界区加热＋４００℃短时等温热处理，可以获得最佳的强塑性配合，并且最高强塑性积（σｂ·δ５）可达３３５６１ＭＰａ·％，远高于块状复合组织。

The effect of micro parameters of martensite ( M ), bainite ferrite ( BF ), ferrite ( F ) and retained austenite ( γ R) multiphase mixed structure on strength and ductility was investigated. The results showed that yield strength of fibrous multiphase mixed structure was related to strengthening state and quantity of movable dislocation in ferrite. The ultimate strength was dominated by the volume fraction of high strength phase ( M+BF ), especially martensite and its strength, while the ductility was related to the length of fiber F , the volume fraction of γ R, and differences of strength among phases. The best balance of strength and ductility was obtained by heat treatment of 1 050 ℃ prequenching +760 ℃ intercritical heating +400 ℃ short time holding. The maximum value of ( σ b· δ 5) reached 33 561 MPa·%, much higher than that of massive mixed structure.