Some standard content:
Mechanical Industry Standard of the People's Republic of China
JB/T6974-93
Wire Spraying Carbon Steel and Stainless Steel
Published on July 27, 1993
Ministry of Machinery Industry of the People's Republic of China
Implementation on July 1, 1994
Mechanical Industry Standard of the People's Republic of China
Wire Spraying Carbon Steel and Stainless Steel
1 Subject Content and Scope of Application
JB/T 6974-93
This standard specifies the main technical requirements and test methods for wire flame spraying and arc spraying of carbon steel, low alloy steel and stainless steel.
This standard is applicable to thermal spraying carbon steel and stainless steel for the purpose of improving wear resistance, corrosion resistance and restoring size. 2 Reference standards
GB8641
Metal Brinell hardness test method
Determination of tensile strength of metal thermal spray coatingsGB11373 General rules for surface pretreatment of thermal sprayed metal partsGB11374 Non-destructive measurement method for thickness of thermal sprayed coatingsMain spraying materials
3.1 Working layer materials
The selection of working layer materials should meet the use requirements of the workpiece and the processability of thermal spraying, or be agreed upon by the supply and demand parties. The types, steel grades and application ranges of the main spraying materials are shown in Table A1 in Appendix A (Supplement).3.2 Adhesive base material
When it is necessary to improve the bonding strength of the coating, the adhesive base can be sprayed. The main adhesive layer materials are shown in Table A2 in Appendix A.4 General rules for spraying process
4.1 Workpiece pretreatment
The sprayed surface of the sprayed part must be strictly cleaned and roughened. Depending on the specific surface condition of the workpiece, roughening methods such as sandblasting, nickel roughening, threading and knurling can be selected. Generally, pretreatment should be carried out in accordance with the requirements specified in GB11373. For specific workpieces such as crankshafts and machine tool guides, appropriate pretreatment processes and shielding measures should be taken to ensure that the spraying process does not damage the workpiece, ensure the coating quality and facilitate coating processing. 4.2. Spraying conditions
4.2.1 Compressed air
The compressed air used for spraying must be purified to prevent oil or water from contaminating the pretreated surface and coating. If oil or water is found in the compressed air during the spraying process, the spraying should be stopped immediately. 4.2.2 Spraying equipment
Before spraying, the spraying equipment must be checked to see if it is intact, to ensure that the spraying process parameters are controlled and adjusted within the required range, and to maintain the stability of the setting specifications. Mechanized spraying operations should be achieved as much as possible. 4.2.3 The spraying area should maintain air circulation to remove unbonded dust. The wind speed is generally controlled within the range of 1 to 2 m/s. When spraying large workpieces, dry compressed air should be used to blow away unbonded dust on the workpiece surface and prevent local overheating. 4.3 Spraying
4.3.1 Pretreatment to spraying residence time
Approved by the Ministry of Machinery Industry on July 27, 1993
Implementation on July 1, 1994
JB/T6974-93
After the pretreatment of the workpiece is completed, spraying should generally begin within 1 hour. If this time limit is exceeded, the workpiece surface to be sprayed should be protected by a clean plastic film or placed in a drying oven. Even in the case of dry air, the workpiece should not be placed for more than 4 hours. 4.3.2 Preheating and temperature control
The surface of the sprayed part to be sprayed should be quickly preheated to 100~150℃, and pollution and overheating should be avoided during the preheating process. During the spraying process, the workpiece cannot be overheated, and the temperature should be controlled at 100~200℃. 4.3.3 Spraying the bonding base layer
When it is necessary to spray the bonding layer, the process parameters that improve the bonding strength of the base layer and the surface roughness of the base layer should be used to continuously spray the bonding base layer. The thickness of the bonding layer is generally controlled within the range of 0.1~0.2mm. 4.3.4 Spraying the working layer
Start spraying the working layer within 1h after spraying the bonding layer. During the spraying process, the process parameters should be kept stable to control the thickness and uniformity of each coating. When coarse particles are found to be bonded to the coating, use a clean tool with a cutting edge to remove the coarse particles. When coarse particles appear continuously, spraying should be stopped and can only be continued after troubleshooting. During the spraying process, dust should be avoided on the surface. If there is dust, it should be removed with a clean steel brush before spraying the next coat. 4.3.5 Flame spraying process parameters
Neutral flame spraying is generally used. Oxygen-acetylene pressure and flow rate, wire feeding speed should be adjusted according to the requirements of the spray gun, with the particle bundle density as the standard. The operating parameters should make each coat even, without local overheating and should have high deposition efficiency. The general selection range is shown in Table 1. The atomizing air pressure is generally not less than 0.5MPa.
Flame spraying process operating parameters selection range Spraying distance
120~150
4.3.6 Arc spraying process parameters
≥60°
Workpiece linear speed
Spray gun moving speed
Appropriate arc voltage and wire feeding speed should be selected, and there should be sufficient atomizing air pressure to make the particle bundle dense and fine, and avoid excessive oxidation and alloy element burning. The general arc spraying process parameter selection range is shown in Table 2. Table 2 Arc spraying process parameter selection range
Arc voltage
Arc current
120~200
Coating post-processing
5.1 Coating post-processing
5.1.1 Oil penetration treatment
Spraying distance
150~200
Spraying angle
Workpiece linear speed
Spray gun moving speed
After the spraying of the steel coating that needs oil penetration treatment is completed, when the coating cools to 40°C, immerse the workpiece in oil for several hours to allow the lubricating oil to penetrate into the pores of the coating. It is best to immerse it in hot oil above 80°C for more than 8 hours. Large parts can be painted with 2 to 3 layers of lubricating oil. 5.1.2 Sealing treatment
After the corrosion-resistant stainless steel coating is sprayed, the sealing agent can be applied immediately to allow the sealing agent to penetrate into the pores of the coating. If necessary, the sealing agent can be applied again after the coating is machined. 5.2 Coating processing
For different spraying materials and coating hardness, the coating can be cut and ground. The selection of tools and processing technology should avoid damage to the coating due to processing stress and local overheating. When turning, the coating should not fall off. When grinding, the coating surface should not be discolored or cracked. During the grinding process, cooling should be strengthened and attention should be paid to dressing the grinding wheel. 6 Technical requirements for coating
6.1 Appearance
JB/T6974-93
The coating surface should be flat and uniform in color. No defects such as cracks, coarse adherent molten particles and traces of overheating are allowed. 6.2 Chemical composition of coating materials
The main chemical composition of coating materials should be consistent with the main chemical composition of spraying materials. For flame spraying, the burnout of main alloying elements should not be greater than 15%. For arc spraying, the burnout of main alloying elements should not be greater than 30%. 6.3 Thickness
The minimum thickness of the coating should meet the design requirements of the coating. The maximum thickness of the coating should not exceed 30% of the minimum thickness. For shaft parts, the minimum thickness of the coating should ensure that the thickness after machining is not less than 0.3mm. 6.4 Coating bonding strength
6.4.1 The coating must be well bonded to the substrate, and there should be no peeling or warping. 6.4.2 The coating with bonding strength greater than 10MPa is qualified coating, and the coating with bonding strength greater than 15MPa is good coating. The coating with tensile strength greater than 20MPa is high-quality coating.
6.5 Coating hardness
For high-carbon pot, carbon tool steel, high-carbon alloy steel and stainless steel coatings that require wear resistance, the coating surface hardness shall not be lower than the requirements of Table 3.
High-quality carbon structural steel
Coating surface hardness lower limit
Hardness HB10/3000
Low carbon steel
Cr13 stainless steel
18-8 stainless steel
Coating performance test method
7.1 Determination of coating thickness
The coating thickness shall be measured in cold state, which can be detected by mechanical measuring tools or by non-destructive measurement method according to GB11374. 7.2 Tensile test of coating bonding strength
The tensile test of coating bonding strength shall be carried out in accordance with the provisions of GB86417.3 Coating hardness test method
The Brinell hardness of the coating shall be determined according to the GB231 metal Brinell hardness test method. When preparing the sample, the coating thickness shall generally be not less than 3mm.
JB/T697493
Appendix A
Wire spray steel thermal spray materials
(Supplement)
The main working layer materials and bonding bottom layer materials of wire spray steel are shown in Table A1 and Table A2 respectively. Table A1
High-quality carbon structural steel
Carbon tool steel
Carbon spring steel
Low alloy steel
Low carbon steel
Medium carbon steel
High carbon steel
Low alloy steel
Low alloy steel
Low alloy steel
Martensitic stainless steel
Type 18-8
Austenitic stainless steel
Main working layer materials
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12CrNi2
20Cr2Ni4||t t||40CrNi
12CrNi3
45CrNi
45CrNiMov
12Cr2Ni4
40CrNiMo
2Cr133Cr134Cr13
OCr18Nig
1Ct18Ni9T
1Cr18Ni11Mo
1Cr18Mn8Ni
CCr18Ni12Mo2Ti
OCr17Ni14 Mo3
Application range
Carbon steel with carbon content of 0.1%~0.25%, the coating is easy to cut, and the wear resistance is better than the same kind of steel. However, the coating shrinkage rate is large, which is suitable for filling holes in shaft castings
Carbon steel with carbon content of 0.25%~0.65%, the coating is easy to cut, has good wear resistance, and the coating shrinkage rate is large, which is suitable for shaft parts and size restoration
Plain steel with carbon content of 0.65%~0.9%, the coating has high hardness, good wear resistance, easy to grind, and small coating shrinkage rate, which is suitable for shaft parts and inner surface spraying wear-resistant coating
Carbon tool steel with carbon content of 0.65%~0.9%, the coating has high hardness, good wear resistance, low shrinkage rate, and is suitable for wear-resistant Coating, mostly used for shaft spraying
Carbon manganese steel with carbon content of 0.62%~0.7%, high coating hardness, good wear resistance, low shrinkage, suitable for wear-resistant coating, mostly used for shaft spraying
Low carbon alloy steel containing Cr and Ni, easy to cut, low shrinkage, the bonding strength between coating particles is higher than that of carbon steel coating, and thick coating can be sprayed
Medium carbon low alloy steel containing Cr and Mn, good coating wear resistance, can be cut, low shrinkage, high bonding strength between coating particles, suitable for wear-resistant coating
High carbon low alloy steel containing Cr and Mn, high coating hardness, wear resistance, low shrinkage, easy to grind, compared with spraying high carbon steel, the bonding strength between coating particles is higher High combined strength
Cr13 type high carbon martensitic stainless steel, good self-hardness of coating, high hardness, wear resistance, low shrinkage, machinable and easy to grind, high bonding strength between coating particles, good impact toughness on large contact surface, suitable for shafts. Low carbon Cr18-Ni9 type austenitic stainless steel, coating has good corrosion resistance and wear resistance. Easy to cut. But the coating shrinkage is large, so be careful when spraying thick coatings and inner surfaces.
Mn-containing low carbon Cr-Ni austenitic stainless steel, coating has good phenolic corrosion resistance and wear resistance, low shrinkage, suitable for spraying thick coatings and inner surfaces.
Mo.Ti-containing low carbon Cr-Ni austenitic stainless steel. The layer has good corrosion resistance, suitable for corrosion resistance. Surface materials with special requirements
QA19-2
QA19-4, etc.
Additional instructions:
JB/T6974-93
Adhesive layer materials
Blunt aluminum wire, self-adhesive material, used for flame spraying carbon steel, low alloy steel, Cr13 stainless steel adhesive layer
Nickel aluminum composite wire, exothermic self-adhesive material, used for spraying carbon steel, low alloy steel, stainless steel adhesive base
Aluminum bronze wire containing 6% to 10% AI, used for arc spraying carbon steel and stainless steel adhesive base on copper substrate
This standard is proposed and managed by the Wuhan Materials Protection Research Institute of the Ministry of Machinery Industry. This standard is drafted by the Wuhan Materials Protection Research Institute of the Ministry of Machinery Industry. This standard is drafted by Wang Jing and Gao Rongfa.
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