Experimental Study on High-Cycle Fatigue Properties of Q420C Steel at Room Temperature

Yang, Liguo; Xing, Yongming

doi:10.1590/1980-5373-MR-2021-0589

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Article • Mat. Res. 25 • 2022 • https://doi.org/10.1590/1980-5373-MR-2021-0589 copy

Experimental Study on High-Cycle Fatigue Properties of Q420C Steel at Room Temperature

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

Q420 structural steel, which is widely used in transmission towers and offshore platform structures, has been studied less than other steels. However, fatigue failure of offshore platform structures can occur under repeated wave loads. The fatigue strength applied stress–number of cycles (S-N) curves of Q420C structural steel were obtained by performing static tensile tests and high-cycle fatigue tests, and the fatigue crack formation and development were investigated based on the fracture morphology. The steel fatigue lifetimes were compared with standard curves and those of steels with various strengths reported previously. The results showed that the fatigue failure of the specimen was typical, and the fracture surface could be divided into a crack initiation region, a propagation region, and a transient fracture region. The Q420C curve was above the BS7608:2014, GB50017-2017, and ANSI/AISC360-10 standard curves. The S-N curve specified in the standard is conservative for Q420C steel. The strength of the steel directly affected its fatigue properties, and the thickness of the steel plate had a significant effect on the fatigue properties.

Keywords:
High-cycle fatigue; fatigue strength; fatigue damage; S-N curve

components	C	Si	Mn	Ni	Cr	Cu	Mo	B	V	C_eq
Measured values	0.14	0.042	0.8	0.007	0.015	0.017	0	-	0	0.278
Factory values	0.07	0.19	1.08	0.01	0.02	0.03	0.004	-	0	-
Product standard	≤0.20	≤0.50	≤1.7	≤0.80	≤0.30	≤0.30	≤0.20	-	≤0.20	≤0.48

Specimen	Test classification	Subgroup	Number
Base metal	tensile test	MCD	3
Base metal	Fatigue test	MCX	12

Sample	F_y/kN	F_u/kN	f_y/MPa	f_u/MPa	F_y/F_u
MCD-1	57.4	65.6	478.3	546.7	0.87
MCD-2	58.0	66.8	483.3	556.7	0.87
MCD-3	56.8	64.5	473.3	537.5	0.88
average	57.4	65.6	478.3	546.7	0.87

Specimen number	k	P_max/KN	S_max/MPa	S/MPa	F/Hz	N
MCX-1	0.7	40.25	335.42	301.88	10	641,002
MCX-2	0.8	46	383.33	345.00	10	444,288
MCX-3	0.65	37.375	311.46	280.31	10	459,783
MCX-4	0.68	39.11	325.92	293.33	10	684,581
MCX-5	0.6	34.5	287.50	258.75	10	809,379
MCX-6	0.55	31.625	263.54	237.19	10	2,000,000
MCX-7	0.58	33.35	277.92	250.13	10	1,949,573
MCX-8	0.62	35.65	297.08	267.38	10	1,504,734
MCX-9	0.72	41.4	345.00	310.50	10	524,530
MCX-10	0.75	43.125	359.38	323.44	10	228,423
MCX-11	0.6	34.5	287.50	258.75	10	824,563
MCX-12	0.65	37.375	311.46	280.31	10	724,212

Data source	Steel grade	f_y/MPa	f_u/MPa	Stress ratio	t/mm	f/Hz	Load waveform
Ref. ²2 Shi G, Zhang JX, Wang Z, Song WJ. Fatigue test of structural steel Q390GJD. Steel Construction. 2014;29(8):21-6. [Chinese]	Q390GJD-16	392.0	565.0	0.1	16	100	Sine wave
Ref. ³3 Shi G, Zhang JX. Fatigue Performance test study on high strength steel Q460C and its welded connection. Building Structure. 2014;44(17):1-6. [Chinese]	Q460C-14	492.27	631.23	0.1	14	100	Sine wave
Ref. ⁴4 Shi G, Zhang JX. Fatigue test of high strength steel Q460D. Industrial Construction. 2014;44(3):6-10. [Chinese]	Q460D-14	465	560	0.1	14	100	Sine wave
Ref. ⁷7 Guo HC, Hao LP, Li YL, Liu YH, Wan JH. Experimental study on fatigue Performance of Q460D high-strength steel and its welded joints. Journal of Building Structures. 2018;39(8):157-64. [Chinese]	Q460D-8	504.9	592.0	0.1	8	30	Sine wave
Ref. ⁸8 Guo HC, Wan JH, Liu YH, Wang DF. Experimental study on fatigue Performance of Q690D high strength steel welded joints. Tumu Gongcheng Xuebao. 2018;51(9):1-9. [Chinese]	Q690D-8	786.3	832.0	0.1	8	20/25	Sine wave
Ref. ²⁵25 Guo HC, Wei HH, Yang DX, Liu YH, Wang ZS, Tian JB. Experimental research on fatigue performance of Q690 high strength steel in marine corrosive environment. Tumu Gongcheng Xuebao. 2021;54(5):36-45. [Chinese]	Q690D-8*	733.0	815.25	0.1	8	30	Sine wave
Ref. ⁵5 Kang L, Hong ST. Experimental investigation on fatigue properties of Q690D high strength steel. Journal of South China University of Technology [Natural Science Edition]. 2021;49(8):35-42.	Q690D-10	800.0	840.0	0.1	10	15/20	Triangular wave
This paper	Q420C-8	478.3	546.7	0.1	8	15	Sine wave

Type of steel	Relationship of S_max-N	Relationship of S-N
Q390GJD-16	S_max = 478.366N^−0.044	S = 444.88N^−0.044
Q460C-14	S_max = 948.593N^−0.10622	S = 882.19N^−0.10622
Q460D-14	S_max = 436.275N^−0.02647	S = 405.73N^−0.02647
Q460D-8	S_max = 933.66N^−0.06950	S = 868.3N^−0.06950
Q690D-8	S_max = 1216.35N^−0.0691	S = 1131.2N^−0.0691
Q690D-8*	S_max = 35776.68N^−0.3349	S = 33272.31N^−0.3349
Q690D-10	S_max = 3255.367N^−0.14941	S = 3027.49N^−0.14941
Q420C-8	S_max = 2588.6N^−0.1555	S = 2407.41N^−0.1555

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