Welding Fasteners to Press-Hardened Materials

Projection welding of fasteners to hot stamped boron steel, press-hardened steels, where an AlSi coating is present.

Fastener welding of weld nuts and studs can be difficult. Fasteners are often considerably softer than the 1500 MPa stamping. With these large change in hardness, the projections in the fastener will collapse prior to a good weld being made. The end result is usually vaporized projections and extended weld times in an effort to forge the materials, instead of welding them. Furthermore, when this type of weld process is incorporated, the end result is weak, inconsistent torque and push-out values, as well as a large heat-affected zone (HAZ).

A M8 nut welded to 2-mm boron. A M6 nut welded to 2-mm boron.
M8 Nut Welded to 2mm Boron | Weld Systems Integrators M6 Nut Welded to 2mm Boron | Weld Systems Integrators

In addition, another concern is the consistency of the base material because of in-house processing.  The influences observed can be oven temperatures, heat cycle times, water flow rates, water temperatures, and quench times.

Challenge:

  • Fasteners are extremely soft compared to the base material.
  • Hot-stamp materials develop AlSi coating in the furnace.
  • Resistive qualities of AlSi coating can be inconsistent across the part, and from batch to batch.
  • Longer weld times with lower weld currents (as typically called for in projection welding charts) makes it difficult to deliver enough heat to the base material, often vaporizing the projections without welding.
  • Consistent projection welding is difficult with most processes, and even with many Capacitor Discharge Welding machines, which may not be properly designed for the projection welding process.

Solution:

As a result, fastener welding using Capacitor Discharge Welders from Weld Systems Integrators (WSI) is your solution. Capacitor discharge resistance welding (sometimes referred to as capacitive discharge) stores energy for extremely fast release of energy with large peak currents. More energy into weld formation and less into heating the surrounding material. The heat affected weld zone, where the properties of the metal have been changed is smaller, minimizing changes in the metallurgy of the workpiece.

Article - Projection Welding of Fasteners | Weld Systems Integrators
Video - Projection Welding of Fasteners | Weld Systems Integrators

Fastener Welding Articles and News

Contact Weld Systems Integrators

Weld Systems Integrators has over 10 years of proven results with tough-to-weld applications, like projection welding fasteners to hot stamped boron, press-hardened steels, extremely- hard aluminum, stainless steel alloys and the latest Gen III materials!

WSI capacitor discharge welders can make good welds on press hardened steels, 100% of the time.

Contact WSI TODAY to discuss projection welding options. Or for immediate assistance, please give us a call at 844-WSI-WELD.