摘要
研究了１１３０℃淬火７１０℃回火的２０Ｃｒ１１ＭｏＶＮｂＮＢ马氏体耐热钢在５５０、６００和６５０℃的持久性能、断口形貌及组织变化．５５０～６５０℃持久强度和持久塑性均随持久时间延长或温度升高而下降。随Ｌ－Ｍ参数Ｐ＝Ｔ（２０＋１ｇｔ）增大，持久强度（σ）沿着以Ｐ≈２０．３０×１０￣３为转折点的两段不同斜率的直线下降，因此，两段直线方程外推长限性能或预测持久寿命更符合实际。在本试验条件下，蠕变断口基本上均为穿晶韧窝型断裂，偶然发现少量沿晶断裂现象。σ－Ｐ曲线出现转折点与穿晶、沿晶断裂机制无明确对应关系。
AbstractStudies were made on the creep rupture properties,fracture morphologies and structure variations at 550℃,600℃ and 650℃ for the martensitic heat-resisting steel 20Cr11MoVNbNB,which had been oil-quenched from 1130℃ and then tempered at 710℃ for 6h.It Was showed that as duration time or temperature increases in the range of 550～650℃,both the creep rupture strength and the duration plasticity decrease.When long-time rupture strength predicted by means of single straight-line equation between stress σ and time Lgt,it is discovered that the higher the temperature,the greater the deviation of extrapclation value.As the L-M parameter P=T(20+Lgt)increases,rupture strength decreases linearly along a broken line(the turning Point p=20.30×10￣3)with two different slopes,therefore it is concluded that the cxtrapolation value of long-time rupture strength is more reliable when two different linear cquations of the relative curve between σ and P used.In present case,the creep fractures fundamentally display transgranular ductile fracture modes,only a small amount of intergranular fracture observed occasionally.Unlike low alloy Cr-Mo-V heat-resisting steel,for the present stcel there is no certain corresponding relationship between the occuring of the tutning poit on σ-P curve and transgranular or intergranular fracture mechanisms.
出处
《钢铁》
CAS
CSCD
北大核心
1994年第10期34-38,共5页
Iron and Steel
