Selection of structure for 20MnMoⅣ
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The material currently used for the end flanges of the packaging equipment is 20MnMoⅣ, but there are two holes with a diameter of φ159 at the ends; it is required to weld stainless steel onto them. Another solution is to use a stainless steel sleeve that is then welded on the outside. Under internal high pressure, the sleeve is tightened, so the requirements are met. But the leader’s answer was: surfacing provides higher strength, so surfacing is the chosen option. However, heat treatment is required after welding the transition layer. Cracks can easily occur; those with experience know that these cracks extend inward into the forging, so any defects that appear can be very problematic. Let’s discuss the structure here. Please give me some advice, seniors.
Using a liner is not a good approach. The two high-pressure reactors we have just designed and manufactured kept leaking at the welds at the base of the liner during hydrostatic testing; it took multiple repairs to resolve the issue, and leaks will definitely occur again during the operation of these devices, making it very troublesome to deal with such problems later on. For 20MnMo forgings, as long as the surfacing temperature and process parameters are well controlled, cracks generally do not occur. So I recommend choosing the surfacing method.