JB/T 7855-1995 Technical requirements for tungsten carbide steel bonded carbide free forgings
Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T7855-95
Tungsten carbide steel bonded hard alloy free forgings
Technical conditions
Published on December 1, 1995
Ministry of Machinery Industry of the People's Republic of China
Implementation on July 1, 1996,
Mechanical Industry Standard of the People's Republic of China
Tungsten carbide steel bonded hard alloy free forgings
Technical conditions
1 Subject content and scope of application
JB/T7855-95
This standard specifies the technical requirements for tungsten carbide steel bonded hard alloy materials for free forging, forging classification, machining allowance and limit deviation of forgings, and inspection rules for forgings.
This standard applies to three grades of forged tungsten carbide free forgings of hammer forging: F3000, F3001 and F3002. 2 Reference standards
GB/T3850
GB10417
GB10418
GB10419
GB10420
3 Terminology
Dense sintered metal materials and cemented carbides Density determination method Technical conditions for tungsten carbide steel-bonded cemented carbide
Determination of transverse rupture strength of tungsten carbide steel-bonded cemented carbide Determination of impact toughness of tungsten carbide steel-bonded cemented carbide
3.1 Forging ratio (expressed in K)
3.1.1 Lengthening
Determination of Rockwell hardness (C and A)
Where: F. is the cross-sectional area of the rough material before lengthening, mm\; F is the cross-sectional area of the rough material after lengthening, mm.
3.1.2 Upsetting
Where: H. Height of rough material before upsetting, mm; H-height of rough material after upsetting, mm.
3.2 Nominal size of forgings
The size of finished product plus machining allowance. 3.3 Forging tolerance
The allowable error of the actual size of the forged forging. 3.4 Forging drawing
A drawing drawn on the basis of the part drawing with machining allowance added. In the drawing, the shape of the forging is represented by a thick solid line, and the shape of the finished product is represented by a double-dotted line.
Technical requirements for raw materials
Tungsten carbide steel bonded carbide materials should comply with the relevant provisions of GB10417. 4.2 Material preparation
Approved by the Ministry of Machinery Industry on December 1, 1995
Implemented on July 1, 1996
JB/T7855-95
Calculate the rough material required for forgings based on the law of constant volume and adding fire consumption. It is advisable to select rough materials with a forging ratio of not less than 2 and a slenderness ratio of less than 2.3. 4.2.2
Classification of forgings
Bars (round bars, square bars, flat bars), blocks, discs, discs with holes, and seamless rings. 6 Bars
6.1 Scope of application
Round and square bars, flat bars with a width to thickness ratio and a length to width ratio of less than or equal to 5:1. It is suitable for bars with a finished product size of no more than 100mm in maximum thickness or width and a length of no more than 500mm. 6.2 Sectional shape and size
6.2.1 Sectional shape and size are shown in Figure 1.
A Round bar
6.2.2 Size
f, L—finished product size;
St.S2, Ls
forging size;
—machining allowance.
6.3 Machining allowance and limit deviation
Square bar
D Forging length surface
6.3.1 Machining allowance and limit deviation are obtained from Table 1. Sectional shape of bar forgings
Flat bar
Except for the thickness size of the flat bar, the machining allowance and limit deviation of each weft section and transverse section size are determined based on the nominal size.
The machining allowance and limit deviation of the thickness of the flat bar are found by the relevant dimensions, which are calculated as half of the sum of the width and thickness (arithmetic mean). The relevant dimensions can be equated with f and f or S and S in Table 1. Then, the machining allowance or limit deviation is obtained according to whether it is the finished product size or the forged 2
size. Or
JB/F7855-95
f+f or f
S+Ss, or S:
Table 1 Machining allowance (2z) and limit deviation of bar forgings Finished size
Cross section
6.3.2 Deviation of cross-sectional shape
Forging size
Bar length L
>200~350
Cross section
Forging size
S, or S:
Cross section
>350～500
Forging size
S, or S2
The limit deviation of the thickness dimension of round and square felling materials and the limit deviation of the thickness and width dimensions of flat bars include shape deviation, that is, the limit deviation of the geometric shape of the bar cross section must be within the range of size deviation. 7 Block type
7.1 Section shape and size
Section shape (see Figure 2)
JB/T7855-95
7.1.2 The size of the free forging block material is the distance between the two parallel sides as the thickness, and the width, length and thickness are equal. 7.2 Machining allowance and limit deviation
7.2.1 The machining allowance and limit deviation can be found in Table 2. The machining allowance and limit deviation of the section size are determined based on the nominal size. Table 2 Machining allowance (22) and limit deviation of block forgings Finished size
Deviation of section shape
Limit deviation
Forging size
Finished size
Limit deviation
Forging size
The limit deviation of the thickness size of the block material includes the shape deviation, that is, the limit deviation of the geometric shape of the block material bearing surface should be within the range of the size limit deviation.
8 Discs
8.1 Scope of application
Discs whose forging dimensions meet the following conditions: 0.ldh≤d
8.2 Dimensions and markings (see Figure 3)
8.3 Machining allowances and limit deviations are shown in Tables 3 and 4. Machining allowances and limit deviations are divided into two grades. Forging accuracy grade F is for general accuracy.
Forging accuracy grade E is suitable for higher requirements. 4
Forging accuracy grade
Outer diameter of finished parts
Note: Dimensions in brackets should be avoided as much as possible.
JB/T7855-95
Machining allowance of disc forgings (d1, and h2) 221, 2z2
>20~30
>30~40
Limit deviation (d and h2) 2z1, 2zz
Outer diameter of forgings
Accuracy grade of forgings
Note: Dimensions in brackets should be avoided as much as possible.
>20~30
>30~40
>40~50
>40~50
>50~60
>50~60
8.4 Forging Examples
Example Forging Dimensions
JB/T785595
Finished product dimensions: d,=140mm, hs=25mm. Required forging accuracy E, machining allowance is found in Table 3: d, is 6mm, h, is 5mm. Forging dimensions: d,=140+6=146mm, hz=25+5=30mm. The calculated limit deviations of forging dimensions d, and h, are found in Table 4. 8.5 Marking example
The finished product has dimensions d1=140mm and hl=25mm. The F3001 steel-bonded carbide free forged disc requires forging accuracy grade E. Its marking is:
Disc 140X25EJB/T7855-95-F30019 Disc with holes
9.1 Scope of application
Disc with holes that meet the following conditions: 0.1d and 20d0.4d
9.2 See Figure 4 for dimensions.
9.3 Machining allowance and limit deviation are shown in Table 5 and Table 6. Machining allowance and limit deviation are divided into two grades. Forging accuracy grade F is suitable for general accuracy. Forging accuracy grade E is suitable for higher requirements. 6
Forging accuracy grade
Finished part outer diameter
JB/T 7855-95
Machining allowance of forgings of disc with holes (d, d and h) 2z1, 2z2, 2z3
Note: Dimensions in brackets should be used as far as possible.
Finished part
Outer diameter d
Forging accuracy grade
Note: Dimensions in brackets should be used as far as possible.
>20~30
>30~40
of) 222, 2z3
Limit deviation (da, d.
>20~30
>30~40
>40~50
>40~50
>50~60
>50~60
9.4 Forging example
Example Forging size
JB/T7855-95
Finished part size: d=160mm, dz=40mm, hi=50mm. Forging accuracy grade F is required. The machining allowance is found in Table 5: d, is 8mm, d, is 12mm, h, is 8mm. Plated part size: d=1 60+8=168mm, d=40-12=28mm, hz=50+8=58mm. The calculated limit deviations of forging dimensions d1, d2 and h2 are obtained from Table 6. 9.5 Marking example
The free forged perforated disc of F3000 steel-bonded cemented carbide with finished dimensions d1=100mm, dz=40mm and h2=50mm requires forging accuracy grade F. Its marking is:
Perforated disc 160×40×50FJB/T7855-95-F300010 Seamless ring category
10.1 Scope of application
Ring. Its forging dimensions shall meet the following conditions: 0.2(dd)≤hz≤d
d.≥50.d,≤240,d. ≥0.8hz
10.2 Dimensions see Figure 5.
10.3 Machining allowance and limit deviation
Machining allowance and limit deviation are divided into two levels (check from Table 7 and Table 8). Forging accuracy grade F is general accuracy.
Forging accuracy grade E is suitable for higher requirements. 8
Forging accuracy grade
Plating accuracy grade
Finished parts
: 200
Forging outer diameter
JB/T7855-95
Seamless ring forging machining allowance (dd
Determination of forging size
-General wall thickness forging size determination
and h,
) 221, 22
Limit deviation (d3, d, and hz) 2z1, 2x forging
>10~15
>15~20
Finished product size: d=200mm.d=120mm, h=20mm. High
>20~25
When the wall thickness is
, the coefficient of the machining allowance
requires the forging accuracy grade F. The machining allowance is found in Table 7: d, is 10mm, d2 is 10nm.h, is 6mm. +2
JB/T7855-95
Forging size: d,=200+10=210mm, d,=12010=110mm, hz=20+6=26mm. Forging dimensions with thinner wall thickness are determined by
. Finished product dimensions: d, = 220mm, d, = 200mm, h, = 25mm. Forging accuracy grade F is required. The machining allowance is found in Table 7: d, is 12mm, d2 is 12mm, and h: is 7mm. When 220-200
0=10, the machining allowance coefficient is 1.3.
Forging dimensions: d, = 220 + (12×1.3) = 236mmd4 = 200 (12×1.3) = 184mm
hz = 25 + (7×1.3) = 34mm.
The limit deviations of the calculated forging dimensions d,, d. and h. are obtained in Table 8. The limit deviation values of d and d. are the same. 10.5 Marking example
The free forged seamless ring (N) with material F3002, forging accuracy grade F, finished product size dl=200mm, d=120mm, h,=20mm is marked as:
Ring N200X120X20FJB/T7855-95--F3002 Forging acceptance
Shape and size of forgings
Shape and size of forgings shall comply with the requirements of this standard. 11.2 Surface quality of forgings
There shall be no obvious cracks or folding defects on the surface of forgings, but defects within the range of machining allowance are allowed to be eliminated by appropriate methods. 11.3 Intrinsic quality of forgings
Ultrasonic flaw detection and metallographic inspection can be carried out as required. 11.4 Mechanical properties of forgings
Density, transverse rupture strength, impact toughness and hardness (annealed state) of forgings can be tested as required. The test methods shall be in accordance with the provisions of GB/T3850, GB10418, GB10419 and GB10420. 11.5 The chemical composition of forgings is not an acceptance item. 11.6 Marking and Certificate
11.6.1 Forgings that have passed the inspection shall be punched or written with paint that is not easy to fall off at a prominent position (or the position required by the contract). Small forgings can be labeled in batches to make marks including production number (or contract number), drawing number (part number), and brand number. 11.6.2 After the forgings have passed the inspection, the forging certificate shall be filled in. Its main contents include: name of forging unit, forging accuracy grade, this standard number, production number (or contract number), drawing number (part number), brand number, production date, number and total weight of forgings (kg), and stamp of the technical inspection department. 11.7 Packaging and Transportation
The packaging and transportation methods shall be indicated in the order agreement. Generally, this box is used for packaging, and dry paper scraps or wood shavings are used as cushioning fillers. The maximum weight of a single box for mailing is 25kg, and the maximum weight of a box for railway consignment is 80kg.3 Machining allowance and limit deviation
Machining allowance and limit deviation are divided into two levels (check Table 7 and Table 8). Forging accuracy grade F is general accuracy.
Forging accuracy grade E is suitable for higher requirements. 8
Forging precision grade
Plating precision grade
Finished parts
: 200
Forging outer diameter
JB/T7855-95
Seamless ring forging machining allowance (dd
Determination of forging size
-Determination of forging size with general wall thickness
and h,
) 221, 22
Limit deviation (d3, d, and hz) 2z1, 2xForging
>10~15
>15~20
Finished product size: d=200mm.d=120mm, h=20mm. High
>20~25
When the wall thickness is
, the coefficient
of the machining allowance
requires the forging accuracy grade F. The machining allowance is found in Table 7: d, is 10mm, d2 is 10nm.h, is 6mm. +2
JB/T7855-95
Forging size: d, =200+10=210mm, d, =12010=110mm, hz=20+6=26mm. The forging size with thinner wall thickness determines
The finished product size is: d, =220mm, d, =200mm, h, =25mm. The forging accuracy grade F is required, and the machining allowance is found in Table 7: d, is 12mmd2 is 12mm, h: is 7mm. When 220-200
0=10, the machining allowance coefficient is 1.3.
Forging size: d4=220+(12×1.3)=236mmd4=200(12×1.3)=184mm
hz=25+(7×1.3)=34mm. wwW.bzxz.Net
The limit deviations of the calculated forging sizes d,, d. and h. are obtained from Table 8. The limit deviation values of d and d. are the same. 10.5 Marking example
The free forged seamless ring (N) with material F3002, forging accuracy grade F, finished product size dl=200mm, d=120mm, h,=20mm is marked as:
Ring N200X120X20FJB/T7855-95--F3002 Forging acceptance
Shape and size of forgings
Shape and size of forgings shall comply with the requirements of this standard. 11.2 Surface quality of forgings
There shall be no obvious cracks or folding defects on the surface of forgings, but defects within the range of machining allowance are allowed to be eliminated by appropriate methods. 11.3 Intrinsic quality of forgings
Ultrasonic flaw detection and metallographic inspection can be carried out as required. 11.4 Mechanical properties of forgings
Density, transverse rupture strength, impact toughness and hardness (annealed state) of forgings can be tested as required. The test methods shall be in accordance with the provisions of GB/T3850, GB10418, GB10419 and GB10420. 11.5 The chemical composition of forgings is not an acceptance item. 11.6 Marking and Certificate
11.6.1 Forgings that have passed the inspection shall be punched or written with paint that is not easy to fall off at a prominent position (or the position required by the contract). Small forgings can be labeled in batches to make marks including production number (or contract number), drawing number (part number), and brand number. 11.6.2 After the forgings have passed the inspection, the forging certificate shall be filled in. Its main contents include: name of forging unit, forging accuracy grade, this standard number, production number (or contract number), drawing number (part number), brand number, production date, number and total weight of forgings (kg), and stamp of the technical inspection department. 11.7 Packaging and Transportation
The packaging and transportation methods shall be indicated in the order agreement. Generally, this box is used for packaging, and dry paper scraps or wood shavings are used as cushioning fillers. The maximum weight of a single box for mailing is 25kg, and the maximum weight of a box for railway consignment is 80kg.3 Machining allowance and limit deviation
Machining allowance and limit deviation are divided into two levels (check Table 7 and Table 8). Forging accuracy grade F is general accuracy.
Forging accuracy grade E is suitable for higher requirements. 8
Forging precision grade
Plating precision grade
Finished parts
: 200
Forging outer diameter
JB/T7855-95
Seamless ring forging machining allowance (dd
Determination of forging size
-Determination of forging size with general wall thickness
and h,
) 221, 22
Limit deviation (d3, d, and hz) 2z1, 2xForging
>10~15
>15~20
Finished product size: d=200mm.d=120mm, h=20mm. High
>20~25
When the wall thickness is
, the coefficient
of the machining allowance
requires the forging accuracy grade F. The machining allowance is found in Table 7: d, is 10mm, d2 is 10nm.h, is 6mm. +2
JB/T7855-95
Forging size: d, =200+10=210mm, d, =12010=110mm, hz=20+6=26mm. The forging size with thinner wall thickness determines
The finished product size is: d, =220mm, d, =200mm, h, =25mm. The forging accuracy grade F is required, and the machining allowance is found in Table 7: d, is 12mmd2 is 12mm, h: is 7mm. When 220-200
0=10, the machining allowance coefficient is 1.3.
Forging size: d4=220+(12×1.3)=236mmd4=200(12×1.3)=184mm
hz=25+(7×1.3)=34mm.
The limit deviations of the calculated forging sizes d,, d. and h. are obtained from Table 8. The limit deviation values of d and d. are the same. 10.5 Marking example
The free forged seamless ring (N) with material F3002, forging accuracy grade F, finished product size dl=200mm, d=120mm, h,=20mm is marked as:
Ring N200X120X20FJB/T7855-95--F3002 Forging acceptance
Shape and size of forgings
Shape and size of forgings shall comply with the requirements of this standard. 11.2 Surface quality of forgings
There shall be no obvious cracks or folding defects on the surface of forgings, but defects within the range of machining allowance are allowed to be eliminated by appropriate methods. 11.3 Intrinsic quality of forgings
Ultrasonic flaw detection and metallographic inspection can be carried out as required. 11.4 Mechanical properties of forgings
Density, transverse rupture strength, impact toughness and hardness (annealed state) of forgings can be tested as required. The test methods shall be in accordance with the provisions of GB/T3850, GB10418, GB10419 and GB10420. 11.5 The chemical composition of forgings is not an acceptance item. 11.6 Marking and Certificate
11.6.1 Forgings that have passed the inspection shall be punched or written with paint that is not easy to fall off at a prominent position (or the position required by the contract). Small forgings can be labeled in batches to make marks including production number (or contract number), drawing number (part number), and brand number. 11.6.2 After the forgings have passed the inspection, the forging certificate shall be filled in. Its main contents include: name of forging unit, forging accuracy grade, this standard number, production number (or contract number), drawing number (part number), brand number, production date, number and total weight of forgings (kg), and stamp of the technical inspection department. 11.7 Packaging and Transportation
The packaging and transportation methods shall be indicated in the order agreement. Generally, this box is used for packaging, and dry paper scraps or wood shavings are used as cushioning fillers. The maximum weight of a single box for mailing is 25kg, and the maximum weight of a box for railway consignment is 80kg.
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