JB/T 6398-2018Heavy stainless acid resistant steel and heat resistant steel forgings - Technical specification (English PDF)

3.1

The purchaser shall specify name, material designation, technical requirements, inspection items, delivery condition and supply quantity of forgings and other additional requirements in the order contract.

3.2

The purchaser shall provide the order drawings and technical documents agreed by the supplier and the purchaser.

3.3

When the purchaser needs to witness the production and test of forgings, it shall propose the specific stages of production and test to be attended.

4.1 Smelting

4.1.1

Steel ingots for forgings shall be smelted by electric furnace and vacuum refined by ladle furnace, or other refining methods such as electroslag remelting agreed by the purchaser.

4.1.2

Without the consent of the purchaser, the supplier shall not intentionally add elements not listed in Table 1 to the steel, and shall also take reasonable measures to prevent the introduction of elements that may affect the corrosion resistance and mechanical performances of the steel from steel-making scrap steel or other materials.

4.2 Forging

4.2.1

The sprue and riser of steel ingot shall have adequate cut-off quantity so as to ensure that the forging is free from injurious defects like shrinkage cavity and excessive segregation.

4.2.2

Forgings shall be forged on a forging press with sufficient capacity to fully forge the entire section to the shape and size of the finished forging as much as possible. When ingots or billet are used for forging, forging ratio of forging's principal section shall not be less than 3 (that of electroslag remelted steel not less than 2); while where mill bars are used, it shall not be less than 1.6.

4.3 Heat treatment

4.3.1

Austenitic profile steel shall be subjected to solution heat treatment, while martensitic profile steel shall be subjected to quenching and tempering. Change of heat treatment state by the supplier shall be agreed by the purchaser.

4.3.2

All heat treatment processes (including heat treatment holding temperature and its deviation, holding time, heating rate and cooling method, etc.) shall be recorded. The temperature deviation of forgings during heat treatment holding time shall not exceed ±10°C.

4.4 Machining

All machining (such as cutting, sawing or grinding) shall be carried out before performance heat treatment as far as possible to avoid cold hardening of the material, unless the cold hardening can be removed by subsequent machining.

4.5 Welding repair

4.5.1

Welding repair may be conducted upon the agreement of the purchaser.

4.5.2

The supplier shall submit welding process specification (WPS), welding process qualification report (PQR) and welding personnel qualification document to the purchaser. Non-destructive testing methods and qualification levels before and after welding repair shall be agreed upon by the supplier and the purchaser.

4.5.3

Drawings for forging's welding repair parts, depth and area, welding materials and non-destructive testing report shall be provided by the supplier to the purchaser.