氧对低合金铁素体低温钢低温韧性的有害作用

对低温工程中应用的 06MnVTi 低温钢板材及其在焊接以后容易出现的低温冲击值明显下降的问题,作了组织分析及热处理试验,发现其根本原因是氧在铁素体相中的过饱和析出及应力应变析出。析出相为弥散的 Fe_3O_4,并因此而引起钢的析出脆性;而造成氧的析出倾向则是由于钢本身的实际合碳量非常低,存在容易富氧的弱点,同时在转炉吹炼过程中又未针对这一特性,加快吹炼速度,而助长了钢中氧的析出脆化敏感性。

Adverse Effect of Oxygen on Cryogenic Toughness of Steel 06MnVTi

The significant decrease in cryogenic impact strength was found liable totake place in 06MnVTi steel plate especially after welding. Structural analysisand experimental heat treatment were therefore made to this steel usually usedin cryogenics. It is found that the key reason for this decrease is the oversatu-rated precipitation and stress/strain induced precipitation of oxygen in ferritephase, i.e. the dispersed Fe_3O_4 in precipitation phase, and precipitation brittle-ness is thus invoked. The reason why the precipitation of oxygen takes plaseis that the actual carbon content in steel is so low that the steel willbe oxygen-enriched. It was, however, not the case in previous converter steelmaking process that attention has been paid to such a feature so as to increasethe blowing rate, so the sensitivity of precipitation brittleness due to oxygencontent in steel was inereased.