材料期刊网

采用定量相分析,硼自射线照象等技术,对不同含硼量的中碳钢40 MnB,在高温加热及冷却过程中,M_(23)(C,B)_6的溶解、析出行为及对钢性能的影响进行了研究。发现析出的M_(23)(C,B)_6的数量及粒度随着钢中的含硼量增加及冷却速度的减小而增加;含硼量不同的钢具有一个相同的临界冷却速度,在这一冷速下,M_(23)(C,B)_6,的析出量达到饱和。M_(23)(C,B)_6的溶解、析出对淬透性和韧性有很大影响。含硼量较低的钢,在相同条件下M_(23)(C,B)_6的析出量较小,且易于溶解,故钢具有较好的综合性能,并对热履历的变化不敏感。提出了一些稳定钢性能的建议。

The effects of dissolution and precipitation of M_(23)(C,B)_6 during heating athigh temperature and cooling subsequently upon the properties of medium carbonsteel 40MnB containing different amounts of boron have been investigated by meansof quantitative phase analysis and boron-autoradiography. The volume fraction andgrain size of M_(23)(C,B)_6 precipitate may be increased with the increase of boroncontent and with the decrease of cooling rate. Although the steels contained dif-ferent amounts of boron, a same critical cooling rate may be appeared at whichM_(23)(C,B)_6 precipitate reached to saturation. The dissolution and precipitation ofM_(23)(C,B)_6 are deeply affected the hardenability and toughness of the steels. Underthe same condition, M_(23)(C,B)_6 in steels containing less boron may be precipitatedout in smaller size and easily dissolved. Thus, they exhibited better combinedproperties and less sensitivity to the change of heat history. Suggestion on stabi-lizing the properties of the steels has been made.