GB/T 33212-2016Steel open die forgings on hammer—General specifications (English PDF)

3.3 Technical Requirements

3.3.1 Steel ingot or steel billet, which is used for forging, shall eliminate surface detects that might affect the quality of forgings. On both sides of steel ingot, there shall be sufficient amount of removal.

3.3.2 Generally speaking, forgings shall be delivered after the first thermal treatment.

The specification of the thermal treatment shall be formulated by the supply-side.

When the demand-side has any special requirements, these requirements shall be negotiated and determined by both sides, then, indicated in drawings or the contract.

3.3.3 After the thermal treatment of forgings, when the generated bending and warpage deformation exceeds the range of tolerance and affects the quality of the forgings or the subsequent processing, it shall be corrected by the supply-side. The corrected forgings shall also guarantee the requirements of the mechanical property.

3.3.4 The mechanical property of commonly used grade of steel for forgings shall comply with the requirements of relevant standards. When there are any special requirements towards mechanical property, they shall be negotiated and determined by the demand-side and the supply-side and indicated in drawings or order contracts.

If there are no special requirements, the property data shall be deemed as longitudinal property data.

3.3.5 In accordance with the design requirements, working characteristics and purposes, the demand-side may comply with the stipulations in GB/T 12363 to determine the category of forgings. In accordance with GB/T 25136, the inspection of

a) In terms of forging surface which needs machining, when it is verified through examination that the depth of the defects can guarantee that over 50% machining allowance will be retained, the defects are allowed to be not eliminated. However, the demand-side's consent will be needed.

b) In terms of forging surface that no longer needs machining, the maximum depth of the renovation shall not exceed the lower deviation of the dimensions of that spot. In addition, the area of renovation shall be smooth.

c) When the depth of defects on forging surface exceeds the machining allowance, if repair welding is needed, the demand-side's consent will be needed. After completely eliminating the defects, conduct repair welding in accordance with appropriate procedures of repair welding. The quality of the repair welding shall comply with the demand-side's requirements towards forgings.

d) In terms of forgings which go through quenching and tempering after forging, the surface defects shall be completely eliminated.

3.3.10 Whether forging surface shall be cleaned and what method shall be adopted for cleaning shall be negotiated and determined by the demand-side and the supply-side during the ordering.

3.3.11 The supply-side shall guarantee that there is no white spot on the forgings.

3.4 Test Methods and Acceptance Inspection Rules

3.4.1 Test methods

3.4.1.1 The inspection of finished forgings shall comply with the stipulations in GB/T 25136.

3.4.1.2 The chemical composition analysis of steel for forgings shall comply with the stipulations in 3.2.5 ~ 3.2.7.

3.4.1.3 Mechanical property test a) The method of tensile test shall comply with the stipulations in GB/T 228.1;

b) The method of impact test shall comply with the stipulations in GB/T 229;

c) The method of hardness test shall comply with the stipulations in GB/T 231.1;

e) After samples are cut off, the samples shall not receive any thermal treatment that might affect the mechanical property.

c) If forging's strength performance index is relatively high, but its plasticity and toughness index cannot satisfy the stipulated requirements, the forging may receive supplementary tempering. The times of the supplementary tempering will not be restricted. After the tempering, conduct the test in accordance with the previous stipulations.

d) If forging's mechanical property test result does not comply with the stipulated requirements, the supply-side may conduct re-thermal treatment on the forging, then, conduct the test in accordance with the previous stipulations. Without the demand-side's approval, the times of the re-thermal treatment shall not exceed 2.

3.4.1.4 On the fracture surface of samples used for the tensile test on forgings, when there are cracks, nonmetallic inclusions and other defects, forgings shall receive macrostructure inspection and ultrasonic flaw detection. Furthermore, the location, range, depth and method of flaw detection, and acceptance inspection conditions shall be clarified. The test method shall comply with the stipulations in JB/T 8467. side may choose on its own (longitudinal, transversal or tangential).

d) In terms of sampling quantity, 2 tensile samples and 3 impact samples may be cut off from each test piece. In accordance with the service conditions of the forgings, the demand-side may also increase or decrease the sampling quantity.

However, it shall be clearly stipulated in the contract or drawings.

3.4.1.8 Please see the requirements of the re-test below:

a) In tensile test, if the sample fractures beyond the gauge, or beyond 1/2 of the distance between the gauge center and the gauge point, and the test result does not comply with the stipulated requirements, then, the sample is invalid.

In an adjacent location of the sample on the forging, re-take a sample for the test.

b) If the sample cannot satisfy the stipulated requirements, in an adjacent location of the sample, take a double quantity of the sample for a re-test. This double quantity of sample shall satisfy the stipulated requirements.

3.4.2 Acceptance inspection rules

3.4.2.1 The inspection and acceptance inspection of finished forgings shall be implemented by the supply-side's technical inspection department.

3.4.2.2 Except from appearance inspection of all the forgings, inspection shall also be conducted in accordance with the inspection items stipulated by the level of inspection, and the inspection items specified in the contract. If necessary, the demand-side may conduct re-inspection.

3.4.2.3 During the acceptance inspection process, the demand-side may arrange staff to evaluate and ratify the acceptance inspection; the supply-side shall provide conditions to make this convenient. However, the demand-side's acceptance […]