Bonding Mechanisms in Resistance Microwelding of 316 Low-Carbon Vacuum Melted Stainless Steel Wires

Abstract

Resistance microwelding (RMW) is an important joining process used in the fabrication of miniature instruments, such as electrical and medical devices. The excellent corrosion resistance of 316 low-carbon vacuum melted (LVM) stainless steel (SS) wire makes it ideal for biomedical applications. The current study examines the microstructure and mechanical properties of crossed resistance microwelded 316LVM wire. Microtensile and microhardness testing was used to analyze the mechanical performance of welds, and fracture surfaces were examined using scanning electron microscopy. Finally, a bonding mechanism is proposed based on optimum joint breaking force (JBF) using metallurgical observations of weld cross sections. Moreover, comparisons with RMWs of Ni, Au-plated Ni, and SUS304 SS wire are discussed.

Crossed-Wire Laser Microwelding of Pt-10 Pct Ir to 316 Low-Carbon Vacuum Melted Stainless Steel: Part I. Mechanism of Joint Formation

“…Similar softening in SS materials was reported in the literature. [7][8][9] Khan et al [9] found that the microhardnesses of the HAZ and FZ were similar when welding 316 LVM SS using the RMW process. The original work-hardened structure of the SS wire was lost due to the thermal cycle of the welding process, leading to recrystallization and resolidification of the microstructure in the HAZ and FZ, respectively.…”

“…[2,[6][7][8][9]13] Khan et al showed that the joint formation mechanism of crossed 316 LVM wires during RMW was a combination of primary fusion welding and partial solid-state bonding when using relatively low welding force of 1.5 kg, [9] while the results of Fukumoto et al demonstrated a mechanism of predominantly solid-state bonding at a higher welding force of 5.6 kg when welding SUS 304 SS wires. [8] Chen reported a progression of mechanisms including solidstate bonding, short-time brazing, and finally fusion welding when RMW was used to join pure Pt wire to 316 LVM sheet.…”

“…[2][3][4][5] Recent literature on microwelding of crossed wires or sheet to sheet, such as Ni sheets, bare and Au-plated Ni wires, 316 low-carbon vacuum melted (LVM) stainless steel (SS), and 304 SUS SS wires have focused on the RMW process. [2,[6][7][8][9] For example, Khan et al [9] detailed the RMW joint formation mechanism and fracture modes of crossed 316 LVM wires. However, the increased complexity of medical devices has brought forth renewed challenges in the welding of dissimilar biocompatible materials.…”

Study on joint formation evolution in laser microwelding of Pt-10%Ir and 316 LVM SS crossed wiresCrossed wire, Laser microwelding, Simulation, Joint formation

“…Current literature on microwelding of crossed wires focuses on RMW processes such as the joining of Ni sheets, bare and Au-plated Ni wires, 316 LVM SS, and 304 SUS SS [3,4,7,8]. To date, only limited literature exists detailing the research on laser microwelding of crossed wire, this is especially true for dissimilar materials.…”

Mechanism of Resistance Microwelding of Insulated Copper Wire to Phosphor Bronze Sheet

“…[1][2][3][4][5][6] Researches on the RMW of a variety of materials including crossed nickel wire, 7) stainless steel wire, 8) Pt wire to stainless steel 9) and nickel-free austenitic stainless steel 10) etc. had been performed.…”