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

Abstract

This paper presents an experimental electro-thermo-mechanical simulation of high-frequency induction (HFI) welding to investigate the effect of temperature and contact normal stress on the weld seam quality. Therefore welding experiments at different temperatures and contact pressures are performed using flat specimens of 34MnB5 steel sheet. In order to characterize the weld seam strength of the welded specimens, tensile and bending tests are performed. To obtain a relative weld seam strength, the bending specimens were additionally hardened prior to testing. With the hardened specimens, it can be shown that the weld seam strength increases with increasing temperature and contact normal stress until a kind of plateau is formed where the weld seam strength remains almost constant. In addition to mechanical testing, the influence of the investigated process parameters on the weld seam microstructure is studied metallographically using light optical microscopy, scanning electron microscopy, EBSD and hardness measurements. It is shown that the weld seam strength is related to the amount of oxides in the bonding line.

The Use of the Linear Energy Calculation Model in High-Frequency Induction (HFI) Tube Welding Technology to Obtain Optimal Microstructure and Weld Geometry

“…The shape of the metal flow lines resulting from the pressure is shown in Figure 7. The metallographic tests were also supposed to confirm metallurgical purity of the weld which means absence of MnSiO3 or Mn2SiO4 (oxides created by manganese and sili- The metallographic tests were also supposed to confirm metallurgical purity of the weld which means absence of MnSiO 3 or Mn 2 SiO 4 (oxides created by manganese and silicon diffusion) in the direction of the hot edges of the welded strip (reacting with atmospheric oxygen) [19], absence of FeO (formed in the case of low heat supply) and absence of Fe 3 O 4 (occurring when the heat supply is too high) [20].…”

“…As a result of squeezing/swelling, the high-carbon liquid phase is extruded in the welding/joining zone while the low-carbon solid phase stays in the bond line. Due to the partially ferritic microstructure, the bond line is also called the "ferritic line" (in the case of carbon steels) [19]. The microstructure of the bond zone, namely the center of weld zone 5, consisted of very fine ferrite grains and fine pearlitic colonies shown in Figure 17.…”

“…As a result of squeezing/swelling, the high-carbon liquid phase is extruded in the welding/joining zone while the low-carbon solid phase stays in the bond line. Due to the partially ferritic microstructure, the bond line is also called the "ferritic line" (in the case of carbon steels) [19]. In zone 4 with the dominant influence of mechanical deformation (Figure 17), occurring next to the bonding zone, ferrite grains grew to the standard series 5-6 due to the influence of heat, moving further into the thermomechanical deformation zone 3 (Figure 18) where the influence of heat and the time of its interaction was too small to initiate the grain growth processes.…”

Improving the Energy Efficiency of the Production of Pipes Welded with High-Frequency Induction

“…After leaving the 3rd fin-pass stand, the open pipe passed through the inductor where high-frequency eddy currents were induced [23,24]. Thanks to this, the convergent edges of the open pipe were heated and squeezed together to form the joint.…”

Localized Induction Heating of Cu-Sn Layers for Rapid Solid-Liquid Interdiffusion Bonding Based on Miniaturized Coils

“…Another field of induction-based joining is the longitudinal welding of pipes from advanced high strength steels (AHSS) by high-frequency induction welding. The authors demonstrated the longitudinal welding of 42SiCr- [33] and 34MnB5-pipes [34] in combination with subsequent heat treatments to manufacture pipes with enhanced mechanical properties.…”