摘要
本文用45及45VS钢研究了室温形变对离子渗氮及气体渗氮的影响,并结合室温形变后再加热时所发生的回复与再结晶过程进行了讨论。结果得出:室温形变后,在再结晶温度以下渗氮时,形变能促进渗氮,使渗氮层厚度增加,硬度升高。影响程度决定于回复再结晶后保留的冷形变效果。渗氮温度愈低,促进作用愈大;随形变量增加,影响效果先增后减,这是因为形变量大时易于发生再结晶。在再结晶温度以上渗氮时,虽然由于再结晶而使心部硬度较未形变的低并使渗层减薄,但却使渗层硬度升高,这是因为在再结晶还未发生前氮已渗入表层提高了表层再结晶温度,并使渗层硬度得到提高。上述结果阐明了形变渗氮能提高性能的原因。
In this paper, the influence of cold working on the plasma nitriding and gas nitriding for steels 45 and 45VS was investegated and discussed with the phenomenon of recovery and recrystallization occured after cold working and reheating. It was found that after cold working, if the nitriding temperature is lower than the recrystallization temperature, the cold working may promote the nitriding process, thus the thickness and the hardness of the nitriding layer may be increassed. The degree of the influence depends on the relained effect of cold deformation after recovery and recrystallization. So that, the lower
the nitriding temperature, the higher the effect of promotion. the influence of cold working is complicated, and it is increased at the beginning and then decreased with the increase of the degree of cold working. This is due to the recrystallization will be occured easilier when the deformation is greater. If the nitriding is carried out above the recrystallization temperature, the hardness of the core and the thickness of the nitriding layer be decreased due to recrystallization but the hardness of nitriding layer may be increased, because
the atoms of nitrogen had entered the surface layer before recrystallization takes place and the recrystallization temperature was raised. Such results can explain the reason why the mechanical properties after chemical thermomechanical treatment are increased.
