Effect of Weld Schedule on the Residual Stress Distribution of Boron Steel Spot Welds

Abstract

2017) Effect of weld schedule on the residual stress distribution of boron steel spot welds. Metallurgical and Materials Transactions A, 48 (6). pp. 2900-2914. Permanent WRAP URL:Press-hardened boron steel has been utilized in anti-intrusion systems in automobiles, providing high strength and weight-saving potential through gage reduction. Boron steel spot welds exhibit a soft heat-affected zone which is surrounded by a hard nugget and outlying base material. This soft zone reduces the strength of the weld and makes it susceptible to failure. Additionally, different welding regimes lead to significantly different hardness distributions, making failure prediction difficult. Boron steel sheets, welded with fixed and adaptive schedules, were characterized. These are the first experimentally determined residual stress distributions for boron steel resistance spot welds which have been reported. Residual strains were measured using neutron diffraction, and the hardness distributions were measured on the same welds. Additionally, similar measurements were performed on spot welded DP600 steel as a reference material. A correspondence between residual stress and hardness profiles was observed for all welds. A significant difference in material properties was observed between the fixed schedule and adaptively welded boron steel samples, which could potentially lead to a difference in failure loads between the two boron steel welds.

Transient Softening at the Fusion Boundary of Resistance Spot Welds: A Phase Field Simulation and Experimental Investigations for Al–Si-coated 22MnB5

“…The most common production relevant strategies to increase the process window are welding with longer welding times and welding current modulation [2][3][4], resulting in welding times of up to several seconds, e.g., in the case of welding with production-related disturbances like gaps [3]. Opting for this solution not only causes a broader heat-affected zone (HAZ), but also can lead to softening at the fusion boundary, described for 22MnB5 with Al-Si [5][6][7][8] and Zn coatings [9]. This effect has also been reported for dual phase steels [10].…”

Validated Multi-Physical Finite Element Modelling of the Spot Welding Process of the Advanced High Strength Steel DP1200HD

“…The maximum current and hence the maximum diameter is limited by the expulsion of molten steel due to overheating. The different characteristic zones of the weld are the FZ, upper critical heat affected zone (HAZ I), sub-critical heat affected zone (HAZ II), and the unaffected base material (BM) as shown in Figure 1 b [ 30 , 31 , 32 , 33 ]. Additional important geometrical quantities used for validation are marked in this figure.…”

Optimization of Double-pulse Process in Resistance Spot Welding of Hot Stamped Steel Sheet

“…Eva et al 8) showed the Dynamic fracture behavior of 22MnB5. Raath et al 9) determined residual stress distributions for boron steel resistance spot welds. Bai et al 10) tested and evaluated the hardness distribution and fracture mode of the joint cross-section.…”