Simply talking about the welding points and welding characteristics of stamping

TIME：2018-09-18

Stamping elbow belongs to one kind of elbow. It has a certain manufacturing process. The forming process of stamping elbow is complex. It needs to be welded according to different materials and uses, and gradually formed under a certain pressure. The forming of stamping elbow needs to be carried out according to a certain process, and the corresponding process should be strictly followed, otherwise the quality problems will arise. A circular ring shell can be cut into four 90 degree elbows or six 60 degree elbows or elbows of other specifications. This process is suitable for manufacturing large-scale push elbows of any specifications whose ratio between the middle diameter of elbows and the inner diameter of elbows is greater than 1.5. It is an ideal method for manufacturing large-scale push elbows at present.

Attention for stamping elbow welding:

1. First punch elbow has certain corrosion resistance (oxygen reactive acid, organic acid, cavitation), heat resistance and wear resistance. It is usually used in power plant, chemical industry, petroleum and other equipment materials. The weldability of stamping elbow is poor. Attention should be paid to welding technology, heat treatment precondition and suitable welding electrodes.

2. When the stamping elbow is welded, carbides are repeatedly heated to reduce corrosion resistance and mechanical properties.

3, and the stamping elbow after welding hardening is large, easy to produce cracks. If the same type of stamping elbow is used for welding, it is necessary to preheat above 300 C and slow cooling treatment around 700 C after welding. If the weldment cannot be heat treated after welding, the stamping elbow electrode should be used.

4. There are titanium calcium type and low hydrogen type in the stamping elbow. Titanium-calcium type can be used for AC and DC, but AC welding penetration is shallow, while easily red, so as far as possible to use DC power.

5. In order to improve the corrosion resistance and weldability of stamping elbow, appropriate amount of irregular elements Ti, Nb, Mo etc. are added, and the weldability of stamping elbow is better than that of stamping elbow. The same type of chromium stainless steel electrode should be preheated above 200 C and tempered around 800 C after welding. If the weldment cannot be heat-treated, chrome nickel stainless steel electrode should be used.

6. The electrode should be kept dry when used. The titanium-calcium type should be dried at 150 C for 1 hour, the low hydrogen type should be dried at 200-250 C for 1 hour (can't be dried repeatedly, otherwise the coating will easily crack and peel off), so as to prevent sticky oil and other dirt in the electrode coating, so as not to increase the carbon content of the welding seam and affect the quality of the welding parts.

7. In order to prevent the corrosion between the eyes caused by heating, the welding current should not be too large, about 20% less than carbon steel electrode, the arc should not be too long, and the layers should be cooled quickly, so the narrow bead should be preferred.

8. Stamping elbow electrode has good corrosion resistance and oxygen resistance, and is widely used in chemical industry, fertilizer, petroleum, medical machinery manufacturing.

The raw material of stamping elbow is steel which is resistant to weak corrosive medium such as air, steam and water, and corrosive medium such as acid, alkali and salt. In practical application, steel resistant to weak corrosion medium is often called stainless steel, and steel resistant to chemical medium is called acid steel. Because of the difference in chemical composition, the former is not necessarily resistant to chemical corrosion, while the latter is generally stainless. Stainless steel is also one of the materials with high strength in building metal materials. Because stainless steel has good corrosion resistance, it can make structural parts to maintain the integrity of engineering design for a long time. Therefore, the stamping elbow will not cause corrosion, pitting, corrosion or abrasion.

The stamping elbow has the characteristics of sanitation, high temperature resistance and ultraviolet resistance. It is a new material with high added value. The stamping elbow pipe has the advantages of smooth inner wall, small heat medium flow resistance, acid and alkali resistance, long service life and easy installation. The heat conductivity of stamping elbow used in floor heating requires good heat conductivity, low temperature heat shock resistance and low temperature impact resistance. During winter construction, the pipe is not easy to be impacted and ruptured, which increases the flexibility of construction arrangements and environmental protection can be recycled, without polluting the environment. However, it will cause secondary pollution if it can not be recovered, and there are problems such as controlling crosslinking degree and crosslinking uniformity, etc. The processing is complex and directly affects the performance of the pipe.

Welding characteristics of stamping elbow:

The welding current should not be too large, about 20% less than that of carbon steel electrode, the arc should not be too long, the interlayer cooling should be fast, and the narrow bead should be preferred.

The stamping elbow is more hardened after welding and easy to crack. If the same type of stamping elbow is used for welding, it is necessary to preheat above 300 C and slow cooling treatment around 700 C after welding. If the weldment cannot be heat treated after welding, the stamping elbow electrode should be used.

The metal ions detached from the workpiece and phosphoric acid in the polishing solution form a phosphate film adsorbed on the surface of the workpiece. This kind of mucous membrane is thinner in the bulge and thicker in the concave. It dissolves quickly because of the high current density in the bulge. With the flow of the mucous membrane, the concave-convex changes constantly, and the rough surface is gradually leveled. The workpiece is used as anode to connect the positive pole of the DC power supply. The conductive materials, such as lead and stainless steel, which are corroded by electrolyte, are used as cathodes to connect the negative pole of the DC power supply. When the electrolyte is immersed in sulfuric acid and phosphoric acid at a certain distance from each other (usually with sulfuric acid and phosphoric acid as the basic components), and the temperature, voltage and current density (generally less than 1 A/cm 2), the tiny bulge on the surface of the workpiece will dissolve first and gradually become a smooth and bright surface.