What kind of heat treatment falls under the category of heat treatments aimed at improving performance during the manufacturing of pressure vessels?

It refers to the improvement of a material’s mechanical properties through heat treatment methods, such as refining grains and enhancing toughness via normalizing treatment； Another example is quenched and tempered sheets: the design requirements specify that the heat-treated state of the material supplied should be the same as its state of use. However, during the manufacturing process, hot stamping leads to temperatures exceeding the original tempering temperature, resulting in a decline in mechanical properties, which can be improved through heat treatment.

The latter case you mentioned should fall under heat treatment to restore the mechanical properties of materials.

This post was last edited by wanlirn on 2016-12-5 at 17:49. If the temperature exceeds the tempering temperature in quenching and tempering heat treatment, the required heat treatment is one aimed at restoring mechanical properties

It refers to the improvement of a material’s mechanical properties through heat treatment methods, such as refining grains and enhancing toughness via normalizing treatment； It is generally normalized, whereas the material was not in a normalized state when it was supplied. . .

Normalizing refines grains and improves toughness； It is generally normalized

Related to recovery performance heat treatment are the concepts of cold deformation and recrystallization, which are independent of the performance heat treatment condition. However, since the recrystallization temperature cannot be determined, performance heat treatment (such as normalizing) is usually used as a substitute. If the forming temperature exceeds the tempering temperature, it is not cold forming; this is considered to destroy the original heat-treated properties, and it is necessary to restore the original heat-treated state. Performance-improving heat treatment is not aimed at counteracting the degradation of material properties caused by the manufacturing process; rather, it is an inherent part of the design itself, and is carried out to achieve higher or specific performance requirements. GB150 does not specify the heat treatment parameters for recovery performance heat treatment and performance improvement heat treatment, nor the specific inspection items for performance test plates; these should be specified in the design documents. These three heat treatment methods are primarily applied to the base material. The test plates for them can be combined with those used for product welding tests, but the inspection items and acceptance criteria for the base material and the welds should differ, and these should be specified in the design documents.

As explained in the definition of the new fixed capacity regulations under 4.2.6.1: \"In addition to the post-weld heat treatment specified by the designer, other heat treatment processes required due to manufacturing processes are to be determined by the manufacturing unit itself.\" . . . When heat treatment is required to achieve the desired strength and toughness parameters, heat treatment to improve the material properties of the compressive components should be carried out. ”I think there could be a practical example to illustrate this.

High-pressure equipment sealed with metal gasket rings requires that the hardness of the gasket ring material be 30HBW to 40HBW lower than that of the ring groove component material. The heat treatment of materials should be considered a treatment to improve those materials.

According to Section 4.6.2.1 of the Large-Diameter Vessels code, (2) when, during the manufacturing process, cold working causes significant deformation of the material or substantial changes in its microstructure, thereby affecting its mechanical properties; or when it is required that the material be in the same heat-treated state as at the time of delivery, and the heat-treated state of the material is altered during manufacturing – this situation corresponds to Article 8.1.4 of GB150, and performance heat treatment must be carried out again using the heat-treated state specified in the design requirements. Compression components shall undergo heat treatment to restore their material properties; however, the concepts involved are different.]； (3) When heat treatment is required to achieve the designed strength and toughness parameters, heat treatment to improve the material properties of the compressive members should be carried out.

I think it counts as well. However, in light of Article 9.1.1.1 of GB150 regarding welded test pieces, performance-improving heat treatment is primarily aimed at the materials of pressure vessels.