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本文介绍了国外近年来在低应力强度疲劳裂纹扩展(LFCP)研究方面的一些情况,着重介绍了应力比R、材料强度、晶粒度和环境介质对LFCP的影响。当提高只或材料强度时,均可增加LFCP的da/dN 和降低(?)K_(tho)对铁素体-珠光体钢,粗化晶粒可以减少da/dN提高(?)K_(tho)对马氏体钢,晶粒度具有相反的影响。多数试验表明,在真空和惰性环境下可以降低LFCP的da/dN和提高(?)K_(tho)文章的后一部分,介绍了两个有关LFCP的模型。高强度钢的氢脆模型,把R、σ_y表征组织因素尺寸的ρ~*以及环境因素,对LFCP的影响联系起来了。应力松弛和循环蠕变模型,则解释了△K_t和△K_(th)的本质,并且说明了从大量试验归纳出来的△K_(ht)=0.7△K_t的简单定量关系。
In this paper, we introduce some recent researches on low stress fatigue crack propagation (LFCP) in foreign countries, and emphasize the influence of stress ratio R, material strength, grain size and environmental media on LFCP. Increasing the da / dN of LFCP and decreasing the K_ (tho) of ferrite-pearlite steel can only increase the da / dN (?) When the material strength is increased or only ) On martensitic steel, the grain size has the opposite effect. Most tests have shown that the latter part of the paper, which can reduce the da / dN of LFCP and increase (?) K tho under vacuum and inert atmosphere, introduces two models of LFCP. The hydrogen embrittlement model for high-strength steels is related to the influence of LF, by using R, σ_y to denote the ρ ~ * of the size of the tissue factor and the environmental factors. Stress relaxation and cyclic creep models explain the nature of ΔK_t and ΔK_ (th) and illustrate the simple quantitative relationship of ΔK_ (ht) = 0.7ΔK_t derived from a large number of tests.