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利用等强度环法测定了在540℃、9.8 MPa下服役3×10~5h后汽缸螺栓用20Cr1Mo1V1钢在不同初紧应力下,540℃保温不同时间后的应力松弛曲线,外推得到了该钢保温1×10~4,3×10~4,1×10~5h松弛后的应力值,并与标准规定的不漏蒸汽时的最小应力值进行了对比。结果表明:采用319.51 MPa的初紧力对已服役3×10~5h的汽缸螺栓进行紧固可基本保证在一个大修期间内汽缸不漏蒸汽。
The stress relaxation curves of 20Cr1Mo1V1 steel for cylinder bolts under different initial tightening stresses and 540 ℃ for different time were measured by isochronous ring method after being used at 540 ℃ and 9.8 MPa for 3 × 10 ~ 5h. The stress relaxation curve was obtained by extrapolation Insulation 1 × 10 ~ 4, 3 × 10 ~ 4, 1 × 10 ~ 5h relaxation after the stress value, and with the standard leak-proof steam minimum stress value were compared. The results show that tightening the cylinder bolts which have been in service for 3 × 10 ~ 5h with the initial tightening force of 319.51 MPa can basically guarantee that the cylinder will not leak steam during an overhaul period.