Is heat treatment required?
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There is a device whose cylinder is formed by welding together different types of steel; one of these steels is 16MnR with a thickness of 32 mm； Another type is 0Cr18Ni9, with a thickness of 28 mm. May I ask the experts: is heat treatment necessary, and if so, how should it be carried out?
Since these are two different materials, and in particular 16MNR has a higher linear shrinkage rate, the stresses generated during welding are greater. If high performance is required for applications involving cylinders, it is recommended to carry out stress-relief annealing.
Your device is a bit strange; I’ve never encountered a cylinder made up of two different types of stiffness, and you also haven’t specified the physical properties of the medium inside it. Here is something for your learning*: The post-weld heat treatment methods for pressure vessels and their components mainly fall into four categories: overall heat treatment in a furnace, segmented heat treatment in a furnace, local heat treatment, and on-site heat treatment. Standards such as GB150 stipulate that, unless otherwise specified in the drawings, welded joints of austenitic stainless steel do not require heat treatment (1. Austenitic stainless steel has a high degree of toughness reserve). 2. Austenitic stainless steels have sensitization zones and are difficult to heat treat). However, when post-weld heat treatment is necessary due to stress corrosion resistance requirements or the needs of the base layer of composite steel plates, special care must be taken to prevent the precipitation of chromium carbides in the austenitic stainless steel base material and welds, which could lead to intergranular corrosion. An effective way to prevent this is to carry out solution treatment on equipment with high corrosion resistance requirements. For containers made of stainless steel or composite steel plates that require corrosion protection, their surfaces generally need to undergo acid washing and passivation. The post-weld heat treatment for such containers should usually be carried out before the acid washing and passivation processes.
This device does exist; it is a piece of equipment used in the production of low-concentration fertilizers, and it seems to be a conversion furnace.
The shift section of small fertilizer plants is equipped with shift converters; there are both medium-pressure and low-pressure shift converters, but I can’t remember their exact structure. If you have the chance, could you give me a rough overview, hehe... By the way, have you decided on this issue yet? Is heat treatment necessary?
It seems no heat treatment is necessary, as heat treatment actually has a negative effect on stainless steel
Recommendation: Perform local heat treatment on the welds and heat-affected zones to eliminate welding stresses.