Stainless steel composite pipe is often used in guardrails and railings. It is relatively good in terms of wear resistance and corrosion resistance. For stainless steel composite pipe, its requirements are relatively strict, and it must be hard and shiny. Stainless steel composite pipe in the production of the steps is more rigorous, which is an important step is welding. The temperature, humidity, welding rod and temperature required for welding are different. Production should be carried out according to the purpose to make its performance and characteristics reach the standard. The technical performance required for welding of stainless steel composite pipe is relatively high, and many masters do not have the ability to weld. The following is a small series to introduce the relevant welding steps for your reference:

1. There are two kinds of stainless steel composite pipe welding rod: titanium calcium type and low hydrogen type. DC power supply can be used as much as possible for welding current, which is beneficial to restrain the redness and penetration of welding rod. The electrode of titanium calcium type drug skin is not suitable for full-position welding, only suitable for flat welding and flat fillet welding. The electrode of low hydrogen type drug skin can be welded in full position.

2, stainless steel composite pipe welding rod in the use of should adhere to the boring. In order to avoid cracks, pits, pores and other defects, the titanium calcium type coating is dried at 150-250 ℃ for 1h before welding, and the low hydrogen type coating is dried at 200-300 ℃ for 1h before welding. Can not be repeatedly dried, otherwise the medicine skin is easy to fall.

3, weld clearance clean, but also to avoid the welding rod stained with oil and other dirt, so as not to add the weld carbon content and affect the welding quality.

4, in order to avoid heating and intergranular erosion, welding current should not be too large, ordinary should be about 20% lower than carbon steel electrode, arc should not be too long, fast cooling between layers, narrow channel welding is appropriate.

5, should try to use short arc welding, arc length of ordinary 2-3mm, the arc is too long prone to thermal cracking.

6, transport: short arc welding should be used, the general does not allow the lateral swing, the goal is to reduce the stainless steel composite pipe welding heat and heat affected zone width, progress weld intergranular erosion resistance and reduce the tendency of thermal cracking.

7, stainless steel composite pipe welding strategy should be stable selection of welding rod, to avoid improper selection of welding rod show hot crack or high temperature heat treatment caused by sigma phase precipitation, so that the metal embrittlement. Refer to the stainless steel composite pipe and dissimilar steel electrode selection specification for selection, and accept the appropriate welding process.

The welding process and manufacturing process of stainless steel composite pipes are relatively rigorous, and the performance requirements for the technology are relatively high. Welding should be carried out in accordance with relevant steps. If problems occur, accidents will occur, especially for bridge guardrails, railings and facilities used in traffic made of stainless steel composite pipes. Therefore, accidents must be qualified for welding!

When stainless steel castings are just produced, we may not notice some of the processing stripes that exist on it. These stripes are not deliberately processed, so why do stainless steel castings have stripes:

Stainless steel castings two metal flow is not the same to fill the cavity and stay of the residual signs, it may be caused by this situation, the mold temperature is low, such as zinc alloy mold temperature is lower than 150 ℃, aluminum alloy mold temperature is lower than 180 ℃, are prone to such defects.

The filling speed of stainless steel castings is too fast, and it is easier to form such stripes, or the amount of paint is too much, and the stripes will be produced. In short, the existence of stripes means that this batch of stainless steel casting products, because it does not have a beautiful appearance, affecting the aesthetic requirements of stainless steel castings.

In normal circumstances, we will do some measures to prevent stainless steel castings. If we want to make the quality of stainless steel castings very good, we need to choose the right casting method. There is also the choice of materials, and then there is a lot of experience extracted from daily work. These statements seem to be valid, and they also help us find a casting method for making. The cross-sectional area and position, shape and size of the inner gate can determine the flow velocity, flow direction and flow state of the molten metal, which is closely related to the quality of the casting. The thin inner gate and the high movement of the metal liquid are beneficial to filling thin walls and various parts, making the appearance of the casting clear, and the speed needs to be adjusted appropriately. Adjusting the mold temperature and increasing the overflow tank can also avoid these problems; in order to avoid stripes, the paint is thin and uniform.

precision casting partsIt is a casting part formed by pouring the casting metal liquid into a certain mold and cold treatment. There are many casting processes for precision castings, including metal mold casting, pressure casting, investment casting, lost foam casting and V method casting, etc. The finished casting products made by the precision casting process are relatively precise, and the later stage can be processed without reprocessing, or only a very small amount of processing. At the same time, precision casting can complete the casting of castings with complex shapes and thin thicknesses, not only for small castings, but also for large castings. From the current situation, the world's precision casting forming process is developing rapidly and has a wide range of applications. In the future, the development trend of precision casting technology is that casting products are getting closer to component products.

General casting partsCompared with the precision casting parts, it is rough and belongs to the scope of forging. General casting is in the case of high pressure at a higher rate of metal liquid quickly filled into the casting solid model, under the action of pressure, so that it is solidified, and then still need to be put into use through the late finishing treatment. However, because of the external force of casting multi-material, the deformation of casting parts often occurs in the process of solidification and molding. General casting is usually suitable for the use of equipment machinery geometric dimensional tolerances and the use of performance requirements are not high castings.

Guardrail accessories manufacturers next for everyone to analyze how to distinguish the quality of zinc steel guardrail accessories.

1. Look at the quality of appearance: the surface of galvanized parts has uniform and complete galvanized layer, the color is consistent, the surface has practicability and smoothness, and there are various pinholes, pitting, peeling, blistering, cutting, yin and yang surfaces, spots, scorching, fog, and spongy deposits on inferior guardrail accessories.

2. Weight of galvanized layer: Due to the galvanizing process, the galvanized layer of galvanized parts of guardrail fittings cannot be completely uniform. The general standard uses two indexes to measure the galvanizing amount: average zinc adhesion amount M and ****** zinc adhesion amount Mmin. It is required that the average value of galvanizing amount shall not be less than M, and the galvanizing amount must be greater than Mmin. The popular point is the arithmetic average of the local thickness measured a specified number of times in the basic measurement plane. * Small local thickness * small value of the local thickness measured on the main surface of a part.

3. Zinc layer adhesion of galvanized parts of guardrail accessories: the galvanized layer is firmly combined with the base metal, and the iron part is in a zinc bath at a certain temperature for a certain period of time, the surface of the iron part reacts with the zinc liquid to form a zinc-iron alloy layer.

The design requirements for precision castings are as follows:
1. Should try to avoid casting with a large level;
2. The casting holes on the plane wall of the casting should be reinforced with convex edges to reduce the wall thickness;
3. The casting structure should be as far as possible so that it can be cooled without hindrance to shrink;
4. There should be a number of connecting columns for large-area sandwich cavities such as waterways and gas paths in castings.

The development direction of stainless steel precision casting industry is as follows:

1. Complete the transformation of the growth mode from labor and resource intensive to technology capital intensive, from extensive pollution type to green intensive type. The quality, variety and quantity of products are equivalent to the world's advanced level, and the proportion of excellent materials is increasing rapidly.

2. Form some research and development and education and training bases with reasonable structure and high overall level of production, education and research, which can continuously send professionals to enterprises, and continuously develop new varieties of high-quality and high-grade casting materials to meet the growing needs of casting materials. At the same time, gradually increase the intensity of technology export.

3. To complete the adjustment of industrial structure, eliminate a number of small precision casting factories with low technical level, poor product quality, serious pollution and poor economic benefits, and form relatively concentrated "small giants" and "famous enterprises" to realize "specialization and large-scale" production.

stainless steel precision castingHas its own advantages, for example, the precision of stainless steel precision casting is very high, and the surface of stainless steel precision casting is very smooth. That is to say, the production and processing of stainless steel precision casting castings can save a lot of machining work, directly for life.
 

Therefore, stainless steel precision casting is very convenient, and very material saving, can save resources.
 

Many casting methods can only cast relatively simple castings, and another advantage of stainless steel precision casting is that it can cast very complex castings. Whether it's a jet blade or a streamlined lumen. It can be said that there is no stainless steel precision casting can not do, only human beings can not think.
 

Although the economic crisis has affected the stainless steel precision casting industry, the decline in raw material prices seems to have brought opportunities to the stainless steel precision casting industry, so the future development of the stainless steel precision casting industry is still in their own hands.

Investment casting is also called lost wax casting, or dewaxing casting. Using investment casting to make a part is usually a more time-consuming process, that is, making a wax prototype of a part and then repeatedly immersing it in liquid ceramic. The ceramic hardens and then the wax is melted, leaving a ceramic mold. The molten metal is then poured into the ceramic chamber. Once the metal solidifies, the ceramic mold is broken and removed, leaving the metal cast. The molds used to create wax patterns can be used many times, but ceramic molds are broken and discarded during the production of each part.

The difference between the chemical composition of cast iron and cast steel is mainly the carbon content and the content of other alloying elements.

Cast iron is an iron alloy containing 2 to 4 percent carbon, while cast steel is a steel alloy containing a lower carbon content, typically 0.2 to 1.5 percent carbon.

Electrogalvanizing: Electrogalvanizing is a commonly used galvanizing process, which can form a uniform, dense, and corrosion-resistant zinc layer on the surface of precision castings. The advantages of electro-galvanizing are uniform coating thickness, beautiful appearance, and good corrosion resistance. It is suitable for the surface protection of precision casting parts. It is often used in the manufacture of furniture, electrical appliances, and auto parts.

Hot-dip galvanizing: Hot-dip galvanizing is a galvanizing process in which the surface of steel is immersed in molten zinc to chemically react with the surface of steel to form a zinc-iron alloy layer. The advantages of hot-dip galvanizing are large coating thickness, good corrosion resistance, and high mechanical properties. It is suitable for manufacturing heavy-duty parts of precision castings and parts with high corrosion resistance requirements. It is widely used in construction, bridges, automobiles, ships and other fields.