Induction Weld Seam Characterization of Continuously Roll Formed TRIP690 Tubes

Abstract

The weld seam characteristics of continuously roll formed and induction seam welded TRIP690 tubes were examined in this work. These tube are subsequently used in automotive hydroforming applications, where the weld seam characteristics are critical. The induction seam welds are created through a solid-state welding process and it was shown that by increasing the induction frequency by 26%, the weld seam width within the heat affected zone (HAZ) reduced due to a plateau in the hardness distribution which was a result of a delay in the transformation of martensite. 2D hardness distribution contours were also created to show that some of the weld conditions examined in this work resulted in a strong asymmetric hardness distribution throughout the weld, which may be undesirable from a performance perspective. An increase in the pressure roll force was also examined and revealed that a wider total weld seam width was produced likely due to an increase in temperature which resulted in more austenitization of the sheet edge prior to welding. The ring hoop tension test (RHTT) was applied to the tube sections created in this work. A Tensile and Notch style ring specimen were tested and revealed excellent performance for these welds due to high peak loads (~17.2 kN) for the Notch specimens (force deformation within weld) and lower peak loads (~15.2 kN) for the Tensile specimens for which fracture occurred in the base metal.

Experimental Investigation of Temperature and Contact Pressure Influence on HFI Welded Joint Properties

“…In tensile tests, the specimens in the welded state break almost always outside the hardened weld seam. This behavior has already been reported [ 17 , 34 , 35 ]. Thereby, the measured forces are often larger than those of the base material [ 36 ].…”

“…Flat specimens can be tested under uniaxial tensile loading according to DIN EN ISO 6892-1 and DIN 50125. This method is used in various publications to test welded specimens with hardened weld seams [ 17 , 34 , 35 ]. In almost all cases the fracture occurs outside the weld seam.…”

“…This paper also proposes a mechanism for joint formation during pressure welding. The mechanism of bonding line formation and further metallographic studies to characterize the weld seam are discussed in many other publications [ 17 , 18 , 19 , 20 , 21 , 22 ]. However, the effect of different temperatures and contact normal stresses on weld seam strength and microstructure formation in HFI welding has never been considered in a scientific publication.…”

A Study on Welding of Porous Metals and Metallic Foams

“…This is despite prior studies showing favorable results in welding aluminum foams using FSW. [ 13,14 ] As the FSW on steel CMF did not result in reasonable welds, any further investigation on the mechanical and microstructure properties of the welded samples was halted, and the focus of the study was diverted toward the induction welding of CMF. This technique would not cause the material to melt into nearby spheres but would instead fuse with adjacent material, forming a strong bond.…”

“…[ 10 ] This process is favored in joining seams along pipes and similar hollow bodies due to its ease of implementation, cost‐effectiveness, and versatility of induction coil geometry. [ 14,15 ] Application of this method in the joining of porous metals has never been reported due to concerns that the inherent porosities within such materials interfere with eddy current flow, exacerbating already present skin effects. However, the presence of a metallic matrix between the porosities of CMF makes induction welding a viable candidate for evaluation in this study.…”