正火预处理对调质26CrMoV钢φ195mm棒材横向-20℃冲击功的改善

Improvement of -20℃ Transverse Impact of 26CrMoV Steel Quenched and Tempered Φ195 mm Bars by Normalizing Pretreatment

对直径为φ195mm的Ti-V微合金化26CrMoV钢(/%:0.27C,0.45Mn,0.25Si,0.006P,0.004S,0.97Cr,0.78Mo,0.002Ti,0.043V)热轧棒材取样后在热处理试验室分别按880℃淬火+645℃回火和925℃正火+880℃淬火+645℃回火两种工艺进行热处理。通过检测其皮下25.4mm处力学性能,发现两种热处理工艺试样的屈服及抗拉强度相近,淬火+回火处理的-20℃横向冲击功为46-47 J,而正火+淬火+回火处理的-20℃横向冲击功为79-86 J,改善效果明显。对比观察发现经正火预处理后钢的回火索氏体及铁素体组织更加均匀、细小。

The Ti-V microalloying 26CrMoV steel(/%:0.27C,0.45Mn,0.25Si,0.006P,0.004S,0.97Cr,0.78Mo,0.002Ti,0.043V)φ195 mm hot-rolled bar is treaded at laboratory by two processes:880℃ quenching+645℃ tempering and 925℃ normalizing:880℃ quenching+645℃ tempering.It is found that at the subsurface 25.4 mm of bar the yield and tensile strength of the bar by the two heat treatment processes are similar,the -20℃ transverse impact energy of the bar treated by quenching+tempering is 46~47 J,but that treated by normalizing+quenching+tempering is 79~86 J,the improvement effect is obvious.It is found that the microstructure of tempered sorbite and ferrite in steel with normalizing pretreatment is more uniform and smaller than that with out normalizing pretreatment.