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采用Gleeble热模拟方法研究了在峰值温度1400℃保温3 s条件下,不同t8/5时间对一种Zr处理钢热模拟粗晶区的组织与力学性能的影响。结果表明,t8/5时间为13~700 s时,试验钢热模拟粗晶区随t8/5的延长,奥氏体晶粒尺寸由50μm增加到接近520μm,相转变组织由贝氏体逐渐转变为晶界铁素体+晶内针状铁素体+晶内多边形铁素体,硬度值由220 HV0.5降低到145 HV0.5,热模拟粗晶区的-20℃冲击吸收能量≥200 J。经扫描电镜分析,晶内铁素体的形核得益于试验钢中大量弥散分布的0.5~2μm的Zr-Ti-O复合夹杂物;断口分析结果表明t8/5时间为80 s和>300 s时,热模拟粗晶区冲击性能降低,与组织中的上贝氏体和粗大的晶界铁素体有关。
The effects of different t8 / 5 times on the microstructure and mechanical properties of a Zr-treated steel in the simulated cold-like zone were investigated by Gleeble thermal simulation at a peak temperature of 1400 ℃ for 3 s. The results show that the grain size of austenite increases from 50μm to nearly 520μm with the increase of t8 / 5 at the time of t8 / 5 from 13 to 700 s, and the phase transformation microstructure changes gradually from bainite Is the grain boundary ferrite + intragranular acicular ferrite + intragranular polygonal ferrite, the hardness value is reduced from 220 HV0.5 to 145 HV0.5, and the thermal simulation crude crystal zone -20 ℃ impact absorption energy ≥200 J. Scanning electron microscopy analysis showed that the intragranular ferrite nucleation benefited from a large number of 0.5 ~ 2μm Zr-Ti-O composite inclusions distributed in the test steel. The fracture analysis showed that the t8 / 5 time was 80 s and> 300 s, the thermal simulation of coarse grain zone impact performance decreases, and the organization of the upper bainite and coarse grain boundary ferrite related.