低碳多元高强结构钢焊接接头疲劳强度试验及分析

Fatigue Tests and Analysis on Welded Joints of High Strength Steel

对低碳多元高强结构钢焊接接头在应力比r=0.12下,采用单点试验法和小样子升降法相结合的试验方法,进行了拉-拉疲劳强度试验。对焊接接头型式对疲劳寿命的影响进行了数理统计分析,并对疲劳断口进行了扫描电镜观察。试验结果和分析表明:对接接头的疲劳极限σ0.12=230MPa;角接接头的疲劳极限σ0.12=130MPa;得到了两种接头型式的S-N曲线和P-S-N曲线方程。在应力水平250MPa、可靠度95%条件下,对接接头的中值疲劳寿命是角接接头中值疲劳寿命的6～18倍。疲劳断口分析认为,焊缝的焊趾和裂纹是影响高强钢疲劳强度的主要原因。

Using the one-point experiment and the minimum of specimens expe riment, the fatigue tests on butt and angle welded joints of high strength steel were carried out at the stress ratio 0.12. The effects of butt and angle welded joints on the fatigue life and the fatigue fracture were analyzed with mathemat ical statistics and SEM. The results indicated that the fatigue limit (σ0.12) o f butt welded joints is 230 MPa and the fatigue limit (σ0.12) of angle welded j oints is 130MPa. Meantime, the fatigue curve questions of S-N and P-S-N were ac hieved. The fatigue life of butt welded joints is 6～18 times as long as that of angle welded joints under conditions of 250 MPa stress level and 95% reliabilit y. The main reason is the effect of weld toe and weld crack on the fatigue limit .