WELDING PROCEDURE for SMAW Nickel

Nickel and nickel-alloy weld metals do not flow and spread like steel weld metal. The operator must direct the flow of the puddle so the weld metal wets the joint sidewalls and the joint is filled appropriately. This is sometimes accomplished by weaving the electrode slightly. The amount of
weave will depend on such factors as joint design, welding position, and type of electrodes. A straight drag (stringer) bead deposited without weaving may be used for single-bead work, or in close quarters on thick sections such as in the bottom of a deep groove. However, a weave bead is generally desirable. When the weave progression is used, it should not be wider than three times the electrode core diameter. Regardless of whether the welder uses weaving or the straight stringer technique, all weld beads should be deposited such that they exhibit the recommended slightly convex surface contour.


When used properly, SMC flux covered welding electrodes should exhibit a smooth arc and no pronounced spatter. When excessive spatter occurs, it is generally an indication that the arc is too long, amperage is too high, polarity is not reversed, or that the electrode has absorbed moisture. Excessive spatter can also be caused by magnetic arc below.

When the welder is ready to break the arc, it should first be shortened slightly and the travel speed increased to reduce the puddle size. This practice reduces the possibility of crater cracking and oxidation, eliminates the rolled leading edge of the crater, and prepares the way for the restrike.

The manner in which the restrike is made will significantly influence the soundness of the weld. A
reverse or “T” restrike is recommended. The arc should be struck at the leading edge of the crater and carried back to the extreme rear of the crater at a normal drag-bead speed. The direction is then reversed, weaving started, and the weld continued. This restrike method has several advantages. It establishes the correct arc length away from the unwelded joint so any porosity resulting from the strike will not be introduced into the weld. The first drops of quenched or rapidly cooled weld metal are deposited where they will be remelted, thus, minimizing porosity.

Another commonly used restrike technique is to strike the arc on the existing bead In this manner, the weld metal likely to be porous can be readily removed by grinding. The restrike is made 1/2 to 1 in. (13 to 25 mm) behind the crater on top of the previous pass, and the restrike area is later ground level with the rest of the bead. This technique is often used for applications requiring that welds meet stringent radiographic inspection standards. It is also noteworthy that it is much easier for welders with lesser levels of skill to produce high quality welds than they can using the “T” restrike technique.