GB/T 33083-2016Heavy carbon structural steel forgings - Technical specification (English PDF)

1 Scope

China's national technical specification for heavy carbon structural steel forgings - the shafts, rotors, cylinders, discs and rings weighing tonnes apiece that go into turbines, presses, rolling mills and heavy machinery, and that cannot be replaced once installed without taking the machine apart. The standard specifies the ordering requirements, the manufacturing process, the technical requirements, the inspection rules and test methods, the acceptance and quality certificate, and the marking and packaging of carbon structural steel forgings for general use in mechanical products. It applies to the ordering, the manufacture and the inspection of heavy carbon structural steel forgings for general use. What distinguishes a heavy forging from a piece of bar stock is that its properties are not uniform: the centre of a large section cools slowly, so the structure and the properties there differ from those at the surface, and the piece may carry segregation and unsoundness at its axis from the ingot it was made from. The standard is written around that fact. It prescribes the manufacturing route - the smelting, the forging with its reduction ratio, the heat treatment and the conditions under which repair welding is permitted - and then the technical requirements: the chemical composition, the mechanical properties by strength grade, the hardness and the non-destructive testing. The inspection clause carries figures showing exactly where the test specimens are to be taken from a solid forging, a hollow cylinder, a disc and a ring, which is the heart of the document, because on a heavy forging the answer depends on where you cut; and it sets the retest and the re-heat treatment that may be applied when a first result fails, together with the acceptance, the quality certificate and the marking. Issued on 13 October 2016 and in force since 1 May 2017.

This Standard specifies the ordering requirements, manufacturing process, technical requirements, inspection rules and test methods, acceptance and quality certificate, marking and packaging, etc. of carbon structural steel forgings for general use in mechanical products. This Standard applies to the ordering, manufacture, and inspection of heavy carbon structural steel forgings for general use.

2 Normative references

The following documents are indispensable for the application of this document. For the dated references, only the editions with the dates indicated are applicable to this document. For the undated references, the latest edition (including all the amendments) are applicable to this document.

GB/T 223 (all parts) Methods for chemical analysis of iron, steel and alloy

GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature ( GB/T 228.1-2010, ISO 6892-1:2009, MOD)

GB/T 229 Metallic Materials - Charpy Pendulum Impact Test Method ( GB/T 229-2007, ISO 148-1:2006, MOD)

GB/T 231.1 Metallic materials - Brinell hardness test - Part 1: Test method ( GB/T 231.1-2009, ISO 6506-1:2005, MOD)

3 Ordering requirements

3.1 The purchaser shall specify the forging name, material designation, number of standard adopted, level, corresponding technical requirements and inspection items, delivery state, quantity supplied, and other additional descriptions in the ordering contract.

3.2 The purchaser shall provide the ordering drawings or related finishing drawings.

3.3 When the purchaser has additional requirements, it shall be agreed upon by the supplier and the purchaser.

4 Manufacturing process

4.1 Smelting The steel for forgings shall be smelted by electric furnace or other smelting methods agreed by the user which guarantee the quality.

7 Acceptance and quality certificate

7.1 The purchaser has the right to select certain test items of the forgings for acceptance. In acceptance inspection or subsequent processing or inspection, if it is found that the forgings do not meet this Standard and the supplementary technical requirements specified in the ordering contract, the purchaser shall promptly notify the supplier; the two parties shall negotiate to resolve.

7.2 The supplier shall provide the quality certificate to the purchaser. The quality certificate shall include at least the following contents:

a) Contract number;

b) Forging drawing number;

c) Number of standard adopted and material designation;