JB/T 7032-2000 This standard is a revision of JB/T 7032-1993 "Large All-Fiber Crankshaft Forgings". Some technical requirements were modified during the revision. This standard specifies the technical requirements, test methods, inspection rules, certificates and markings for integral large all-fiber crankshaft forgings. This standard applies to the ordering, manufacturing and acceptance of large all-fiber crankshaft forgings with a main journal diameter of 120 to 350 mm for diesel engines. This standard was first issued in September 1993, and this is the first revision. JB/T 7032-2001 Large All-Fiber Crankshaft Forgings JB/T7032-2001 Standard download decompression password: www.bzxz.net

ICS77.140.85
Machinery Industry Standard of the People's Republic of China
JB/T7032-2001
Large full fibre crankshaft forgings2001-06-04 Issued
China Machinery Industry Federation
2001-10-01 Implementation
JB/T7032-2001
This standard is a revision of JB/T7032-1993 "Large full fibre crankshaft forgings". The following changes have been made during the revision: 1. Deleted the 35# steel in the original standard;
2. Cancelled the backward open-hearth smelting method in 4.1.1; 3. Modified some technical requirements and indicators, which are stricter than the original standard. This standard replaces JB/T7032-1993 from the date of implementation. This standard is proposed and managed by Deyang Large Castings and Forgings Research Institute. The drafting unit of this standard is Tianjin Heavy Machinery Group Corporation. The main drafters of this standard are Sun Liguo and Xiao Chengren. This standard was first issued in September 1993 and this is the first revision. 1 Scope
Machinery Industry Standard of the People's Republic of China
Large Full Fiber Crankshaft Forgings
Largefull Fiber Crankshaft ForgingsJB/T7032-2001
Replaces JB/T7032-1993
This standard specifies the technical requirements, test methods, acceptance rules, certificates and markings for integral large full fiber crankshaft forgings. This standard applies to the ordering, manufacturing and acceptance of large full fiber crankshaft forgings with a main journal diameter of 120~350mm for diesel engines. 2 Reference Standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T222—1984
GB/T223—1981~1997
GB/T226—1991
GB/T228—1987
GB/T229—1994
GB/T231—1984
GB/T10561—1989
CB/T973—1981
JB/T9020—1999
YB/T5148—1993
3 Order Contents
Sampling Method for Chemical Analysis of Steel and Chemical Analysis of Finished Products Permissible deviation of composition Chemical analysis methods for steel and alloys
Macrostructure and defect acid etching test method for steel Metal tensile test method
Metal Charpy notch impact test method
Metal Brinell hardness test method
Microscopic evaluation method for non-metallic inclusions
Quality requirements for magnetic particle flaw detection of diesel engine parts
Ultrasonic inspection of large forged crankshafts
Method for determination of average grain size of metals
Both the supplier and the buyer shall specify the adopted standards, material grades, corresponding technical requirements and inspection items 3.1
and other additional instructions in the order contract or order agreement.
3.2 The buyer must provide the supplier with an order sample drawing (such as a rough processing drawing or a fine processing drawing) and indicate the power output end, size, tolerance, surface roughness and test block (sample) position of the product. 4 Technical requirements
4.1 Manufacturing process
4.1.1 Smelting
The steel for crankshaft forgings shall be smelted by electric furnace or other methods agreed by both parties. 4.1.2 Forging and heat treatment
4.1.2.1 When forging crankshaft blanks, a process method shall be adopted to ensure that the entire metal section is fully forged and a uniform structure is obtained. The better end of the steel ingot is the power output end of the crankshaft. 04 Approved
2001-10-01 Implementation
JB/T7032-2001
Crankshaft application Roughly processed crankshaft blanks are locally heated quickly and manufactured by full fiber forging method. 4.1.2.2
Both crankshaft blanks and forgings shall be subjected to timely post-forging heat treatment. 4.1.2.3
4.1.3 Straightening
After the performance heat treatment, the crankshaft forgings are allowed to be straightened, and the stress relief treatment should be carried out in time after straightening. 4.2 Chemical composition
4.2.1 The results of chemical composition smelting analysis should comply with the requirements of Table 1. If the purchaser has special requirements, it will be negotiated separately. Table
Chemical composition
35CrMo
42CrMo
0.42~0.50
0.32~0.40
0.38~0.45
0.15~0.37
0.17-0.37
0.50~0.80
0.40~0.70
0.50~0.80
The allowable deviation of chemical composition of finished products shall comply with the provisions of GB/T222. 4.2.2
4.3 Mechanical properties
The mechanical properties test results of crankshaft forgings shall comply with the provisions of Table 2. P
Table 2 Mechanical properties
35CrMo
42CrMo
Heat treatment type
Normalizing or
Normalizing + tempering
Section size
120~250
>250~350
120~250
>250~350
120~300
>300-350
120~ 160
>160~250
>250~350
560~750
560-720
590~740
590~740
≥685
≥635
800-950
750-900
690~840
Note: The hardness value is a reference value when the mechanical properties are qualified. 4.4 Metallographic inspection
General requirements
(0o2）
≥(550)
≥（550)
0.80~1.10
0.90~1.20
0.15~0.25
0.15~0.25
162~217
197~286
187~255
207~269
268~321
269~302
241~286
The macrostructure of crankshaft bad material is not allowed to have defects such as cracks, folds, shrinkage holes and residual defects. The macrostructure defects should not be greater than those specified in Table 3. Table 3
Grain size and non-metallic inclusions
General porosity
Ingot-shaped segregation
The measured grain size of crankshaft forgings after heat treatment shall not be coarser than Grade 5. Spot segregation
Subcutaneous bubbles
Sectional dimensions
JB/T7032-2001
Table 4 Non-metallic inclusions
Inclusion categories
Note: Sectional dimensions refer to the section dimensions of the main journal in the order drawing. 4.5 Non-destructive testing
4.5.1 Magnetic particle testing
For crankshaft forgings, the quality requirements for magnetic particle testing shall be selected by both the supplier and the buyer in accordance with CB/T973. 4.5.2 Ultrasonic flaw detection
4.5.2.1 The ultrasonic flaw detection areas are divided into main critical areas (Zone I), secondary critical areas (Zone II), and non-critical areas (Zone III), see Figure 1 for details.
4.5.2.2 No defects such as white spots and cracks are allowed inside the crankshaft forgings. 4.5.2.3 Defects with an equivalent diameter less than or equal to Φ2mm are not counted. For defects greater than Φ2mm, the spacing should be greater than three times the equivalent diameter of the defect.
4.5.2.4 The defect limit values ​​of each zone are as follows:bzxZ.net
Zone I: Defects with an equivalent diameter greater than 2mm are not allowed. Zone II: Defects with an equivalent true diameter greater than Φ4mm are not allowed. Zone III: Defects with an equivalent diameter greater than 6mm are not allowed. S/5
|5Test methods and acceptance rules
Figure 1 Division diagram of ultrasonic flaw detection areas
5.1 Chemical composition analysis
The supplier shall sample and analyze each furnace of molten steel during pouring. When multiple furnaces are poured together, the chemical composition shall be calculated according to the weight method, and the analysis method shall be carried out in accordance with the provisions of GB/T223. Finished product analysis is allowed to be carried out on mechanical properties test specimens, and the allowable deviation shall be carried out in accordance with the provisions of GB/T222. 5.2 Mechanical properties test
5.2.1 The mechanical properties test specimen may be left at the free end of the crankshaft or agreed upon by both parties, and the test specimen diameter is: d.=
Where: d—test specimen diameter, mm;
A—longitudinal cross-sectional area of ​​the first crank journal, mm2; [4 +A,]×4
JB/T7032-2001
5.2.2 After heat treatment, each crankshaft shall be cut or sleeved with a longitudinal specimen on the circumference of R/2 from the test block surface, and the number of samples shall be one tensile specimen and three impact specimens.
5.2.3 The tensile test shall be carried out in accordance with the provisions of GB/T228, the impact test shall be carried out in accordance with the provisions of GB/T229, and the Brinell hardness test shall be carried out in accordance with the provisions of GB/T231.
5.3 Nondestructive testing
5.3.1 The magnetic particle testing shall be carried out by the user in accordance with the provisions of CB/T973. 5.3.2 Ultrasonic testing shall be carried out in accordance with the method specified in JB/T9020. 5.3.3 The crack detection of the crankshaft shall be carried out after rough machining or semi-finishing machining, and the surface roughness of the crack detection shall be Ra<6.3μm. 5.3.4 Grain size and non-metallic inclusion inspection 5.3.4.1 The grain size inspection of the crankshaft forging can be carried out on the crankshaft body or on the impact specimen. If the grain size inspection is carried out on the crankshaft body, a representative crankshaft shall be taken from the crankshaft forgings of each heat treatment furnace to inspect two points, and the inspection position shall be on the outer crank arm of the crankshaft at both ends of the crankshaft.
5.3.4.2 The evaluation method of grain size shall be carried out in accordance with the provisions of YB/T5148. 5.3.4.3 The inspection of non-metallic inclusions shall be carried out in accordance with the provisions of GB/T10561. 5.3.4.4 The bad crankshaft shall be inspected at low magnification, and the inspection method shall be carried out in accordance with the provisions of GB/T226. 5.4 Retest
5.4.1 Retest is allowed when the mechanical property test fails, but retest is not allowed when the test result fails due to white spots, etc. 5.4.2 When one specimen fails the test, two specimens at adjacent positions shall be selected for retest, and the test results of both specimens must meet the requirements.
5.4.3 When any mechanical property or grain size requirement is unqualified in the retest results, the supplier may reheat treat the forging, but the number of reheating shall not exceed three times. The reheat treated forging shall be subjected to mechanical property test in accordance with the requirements of 5.2. 6 Quality Certificate
When delivering, the supplier must provide the purchaser with a certificate of conformity. The certificate of conformity shall include the following: a) Order contract number;
b) Order drawing number;
c) Product steel grade number;
d) Standard number;
e) Melting furnace number;
f Main dimensions and weight of the product;
g) Chemical composition analysis results;
h) Mechanical properties test results;
i) Nondestructive testing results;
j) Other additional inspection results.
7 Marking and Packaging
7.1 The supplier shall mark each forging with the contract number, furnace number, etc. and circle it with white paint. 7.2 The supplier shall pack according to the transportation conditions.
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