We just built one similar to that here in the shop. The heating elements will probably be added tomorrow.
So does that mean you can apply color to a stainless steel barrel?
If you have a custom rifle that has not been stress relieved you might want to read up some on finishes before you bake it.
Thanks Berg,All custom rifle barrels that I'm aware of have been stress relieved at least twice, once at the mill and once at the barrel maker. Button rifling (Rifling by displacement) and hammer forging (hamming the exterior barrel around a mandrel) introduce more stress than cut rifling (rifling by removing material) to the barrel but are still stress relieved at higher temperatures than we would cure the paint.More info on stress relief of 4130 and stainless steel.Stress relief is a type of heat treatment used to reduce or remove internal stress induced into metal components from various manufacturing methods (bending, shearing, forging, sawing, machining, grinding, milling, turning, welding, heating, cooling). As a general rule, the larger or more complex the part, the greater the amount of internal stress present.In heat treating, rapid cooling/quenching alone or in combination with pre-existing internal stresses can result in unwanted distortion, brittle fracture and stress corrosion cracking if near welds in certain grades of metal.Stress-relief operations are typically done by subjecting the parts to a temperature approximately 40-75ºC (105-165ºF) below the A1 transformation temperature — about 727ºC (1340ºF) for steel. Stress relief is typically performed for carbon steel at approximately 500-650ºC (930-1200ºF). The elimination of stress is not instantaneous (that is, the process is a function of both temperature and time). To achieve the maximum benefit, some time at temperature (typically one hour per 25 mm of cross-sectional area once the part has reached temperature) is required. This removes more than 90% of the internal stresses. Stress relief on alloy steels is often done at (slightly) higher temperatures. After removal from the furnace or oven, the parts are air cooled in still air. Rapid cooling will only serve to reintroduce stress and is the most common mistake made in stress-relief operations.For tool steels, the process is similar. It is common to perform a stress-relief operation in the temperature range of 500-550°C (925–1025°F) allowing the parts to slowly cool to room temperature before subsequent operations.For stainless steels, the situation is more complex. Stress relief is done in the range of 290-425°C (550-800°C), which is below the sensitization range. The operation is typically broken down into several cases.1. When stainless steel sheet and bar experience a reduction in area in the neighborhood of 30%, there is a peak in internal stress coupled with an increase in both tensile and yield strength. Stress relief will help reduce movement in subsequent machining operations. Since it is performed at temperatures below 425°C (800°F), carbide precipitation and sensitization to intergranular attack (IGA) are not a problem even in the higher carbon grades.2. After machining, stress relief at 425-595°C (800-1100°F) is normally adequate to reduce stress and minimize distortion that would otherwise exceed dimensional tolerances after machining. If weldments are involved, only the low-carbon "L" grades or the stabilized 321 and 347 grades above 425°C (800°F) as the higher carbon grades are sensitized to IGA when heated above about 425C (800F).Link:http://www.industrialheating.com/
Most rifle actions have not been stress relieved from the factory, (I know that some rifle builders do stress relive the action before machining) if you true an action that has not been relieved, then barrel the action, then bake a finish on, it is "possible" that the action will "move" as the stress is relieved. If you just spent a bunch of time truing the action face and lugs that might not be a good thing.
Have you heard of a factory action moving during an oven cure at 350ºF?I’m not trying to be argumentative; I’m just trying to understand the real harm in oven cure paint at its relatively low cure temperatures as it pertains to gun parts. Thanks again for your comments.
This took way to much time, my last post on the subject, I certainly did not mean to hurt anyone's feelings. All this info. is free, so that is probably what it's worth. GO SHOOT