Investigation on fatigue fracture behaviors of spot welded Q&amp;P980 steel

Wang, B.; Duan, Qingling; Ge, Yicheng; Pang, J.C.; Li, X.W.; Wang, L.; Zhang, Z.F.

doi:10.1016/j.ijfatigue.2014.03.004

Cited by 54 publications

(21 citation statements)

References 25 publications

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“…Wang et al [17] noted that the mechanical strength of RSW joints of 1.6 mm thick Q&P980 and DP780 steel sheets (the latter steel being examined for comparison purposes) was approximately the same after both shear tension and cross-tension tests. Studies conducted on TWIP steel sheets [18][19][20] have evaluated the effect of process parameters, and in particular the welding current, clamping force, and welding time on the microstructure, shear tension strength, and fracture mode of RSW joints.…”

Section: Introductionmentioning

confidence: 99%

Dissimilar Resistance Spot Welding of Q&P and TWIP Steel Sheets

Spena

Maddis

Lombardi

et al. 2015

Materials and Manufacturing Processes

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Dissimilar resistance spot welding of TWinning Induced Plasticity (TWIP) andQuenching and Partitioning (Q&P) steel grades has been investigated by evaluating the effects of clamping force, welding current, and welding time on the microstructure, shear tension strength, and fracture of welded samples. The spot welding of TWIP and Q&P steels promotes the occurrence of an asymmetrical weld nugget with a greater dilution of TWIP steel because of its lower melting temperature and thermal conductivity. As a result, weld nuggets exhibit an austenitic microstructure. TWIP steel undergoes a grain coarsening in the HAZ, whereas Q&P steel undergoes some phase transformations.Welded samples tend to exhibit higher shear tension strength as they are joined at the highest welding current, even though an improper clamping force can promote excessive metal expulsion, thereby reducing the mechanical strength of the welded joints. Shear tension welded samples failed through interfacial fracture with partial thickness fracture mode for a low welding current, while partial thickness with button pull fractures were observed when a high welding current was used. The weld spots predominantly failed at Downloaded by [FU Berlin] at 17:58 02 July 2015 2 the TWIP side. However, as TWIP steel can work harden significantly in the more resistant welded joints, the failures occur, instead, at the Q&P side.

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Section: Introductionmentioning

confidence: 99%

Dissimilar Resistance Spot Welding of Q&P and TWIP Steel Sheets

Spena

Maddis

Lombardi

et al. 2015

Materials and Manufacturing Processes

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show abstract

“…In the HAZ, the hardness value is varied in different regions, that is, the regions near the base material show a lower hardness value compared with the region near the nugget. Similar results were also found in spot welded Q&P980, DP780 and DP980 . There exists a zone near the base material where the hardness value is obviously lower than that of the base material, and such a zone is called soft zone as indicated in Fig.…”

Section: Resultsmentioning

confidence: 95%

“…used the finite element method to calculate the stress intensity factor and J ‐integral and found that the kinked angle of fatigue crack was about 75°. Wang et al . also observed that the kinked angle of spot welded Q&P980 was nearly 75°.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, it is of significant importance to investigate the fatigue performance of spot welds for achieving a safe and reliable design. Over the past decade, many studies on the fatigue behaviour of steels after resistance spot welding have been carried out . For example, it was found that the fatigue performance of spot weld was mainly determined by the geometric factor rather than the material and microstructure .…”

Section: Introductionmentioning

confidence: 99%

“…noted that for a thin spot welded sheet, its microstructure had an important effect on the fatigue strength; however, as the sheet thickness increased, the fatigue strengths of spot welds of different materials were almost the same. More recently, Wang et al . found that the fatigue performances of spot welded Q&P980 (1.6 mm) and DP780 (1.6 mm) were nearly the same, regardless of base material.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Fatigue fracture behaviour of spot welded B1500HS steel under tensile‐shear load

Wang

Duan

et al. 2015

Fatigue Fract Eng Mat Struct

Self Cite

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The microstructural characterizations, micro‐hardness measurements and fatigue tests of B1500HS steel spot welded tensile‐shear specimens were performed. The high hardness values of base material (470 HV) and nugget (515 HV) are closely related to the dominant formation of martensitic microstructures, while the occurrence of soft zone is the result of the formation of ferrite phases in inter‐critical heat‐affected zone (HAZ), as well as martensite tempering in sub‐critical HAZ. The fatigue failure modes involve the fracture along the circumference or along the direction of width. The fatigue property of spot welded B1500HS is found to be better than that of spot welded M190 because of the thicker sheet and suitable nugget size, which follows the standard rule of 5t0.5, where t is the sheet thickness.

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Effects of Process Parameters on Spot Welding of TRIP and Quenching and Partitioning Steels

Spena

Cortese

Maddis

et al. 2016

steel research int.

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This study investigates the resistance spot welding between a quenching and partitioning (Q&P) steel and a transformation-induced plasticity (TRIP) steel. The effects of welding current, electrode force, and welding time on microstructure and mechanical properties have been assessed by shear tension and hardness tests. Welding electrical parameters have been monitored to detect metal expulsion. An adequate shear strength of lap-joint Q&P/TRIP spots is observed, with the best mechanical strength (14kN) being obtained with a 7.5kA current. Metal expulsion is detected for the highest current (9kA), which limits the shear strength and nugget size of spot welds. The lap-joint samples mainly break by partial thickness with button pull; interfacial fractures only occur in the samples with the smallest nuggets

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Investigation on fatigue fracture behaviors of spot welded Q&P980 steel

Cited by 54 publications

References 25 publications

Dissimilar Resistance Spot Welding of Q&P and TWIP Steel Sheets

Dissimilar Resistance Spot Welding of Q&P and TWIP Steel Sheets

Fatigue fracture behaviour of spot welded B1500HS steel under tensile‐shear load

Effects of Process Parameters on Spot Welding of TRIP and Quenching and Partitioning Steels

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