The material used for your compression spring is probably unsuited for welding. While it is possible to weld a high carbon, high strength material like spring steel to a low carbon sheet steel, the resulting weld will be of poor quality-- brittle, prone to cracking, etc. If your intention is to weld a compression spring that has inactive coils at the ends (ground coils or just inactive turns), and the subsequent weld is not highly stressed, or dynamically stressed (fatigue environment), then it may be possible to obtain a suitable weld, with proper weld conditions (pre-heat, post-heat, filler material, etc.) I would recommend doing a google search (
I agree with TVP, that most likely, a weld made to a spring is unsuitable for most applications. You have to evaluate your application on an individual basis. Additional things to consider however, is not only will the weld most likely be hard and brittle, but the heat will change the temper of the spring, and its properties. All springs I can remember having seen welded, have eventually failed. I have seen failures both in the weld, and in the spring. If you application permits, you also might consider brazing the spring to the sheet metal. If done properly, it should effect the properties of the spring less than welding, and the braze should be less brittle than a high carbon content weld.
It is certainly a bad idea, although it may be possible. Have you considered resistance spot welding? It MIGHT be able to join the materials with minimal impact on the spring metallurgy, but you still would want to apply it only to unstressed coils. Any conventional type of welding is an extremely bad idea, as the required preheating for welding the high carbon steel will anneal the spring and it won't be a spring anymore. Without preheating, you just get a brittle weld that will break.
I aggree with all of you that welding of spring is a bad idea due to High Carbon. But I want ti try it for certain application.
I have taken trial on resistance spot welding & I could weld the Spring with inactive turns.
But I am uncertain whether the weld / spring will withstand for dynamic conditions. Also I wish to know how to qualify such welding on spring?
Well, as long as you understand that this represents a poor condition for welding, the following items should be considered for the proper qualification of this weld:
1. Visual inspection of the weld. Look for obvious defects like cracks, porosity, etc. Other welding faults include burn-through, pitting, gaps between the spring and sheet, metal press-out between spring and sheet (spatter) and surface spatter, excessive indentation, and electrode fusing.
2. Destructive testing of the weld. Typical tests would be shear, peel, and torsion testing. Evaluate test for ultimate load/force. Evaluate fracture surfaces for cracks, pores, spatter, insufficient bonding/penetration/fusion, inclusions, etc. An intact weld will produce a weld button equal to the spot weld diameter. Destructive tesing should also include dynamic testing should as fatigue and impact conditions. Parts that pass an ultimate test will quite often fail these tests due to internal defects or cracks that nucleate and propagate during the test.
3. Metallurgical inspection of the weld. Prepare metallographic cross-sections and inspect for penetration, weld bead diameter, porosity, inclusions, blowholes, etc. Etch the cross-section with acid and evaluate the microstructure. Is the heat-affected zone excessive? The fusion zone will probably have a terrible microstructure (almost entirely untempered martensite). You may want to consider a low-temperature stress relief that will also serve to temper the martensite in the weld so that is will not be as brittle.
