The "Q" in the name represents yield strength, and "345" represents that the lower limit of yield strength at room temperature is 345MPa.
In the market, Q345 steel has always been very popular. However, many people have noticed that even though it is called Q345. However, the riveting and welding prices of Q345 thick plates (above 30mm) of different grades and thicknesses are also different. The price gap is extremely significant, especially for thick plates with a thickness of 30mm or more. If you buy them more expensively, you will suffer huge losses.
Prices vary greatly depending on the grade
Q345 steel is divided into five grades from A to E. The higher the grade, the better the impact toughness and the more expensive the price. Grade A does not carry out low-temperature impact testing, and its price is the lowest; Grade E needs to pass the impact test at minus 40 degrees, and its price is the highest.
The key indicator for distinguishing grades is phosphorus and sulfur content. E-grade steel has the lowest phosphorus and sulfur content and the highest purity, so the smelting cost is higher. Projects in cold areas basically use D-grade or E-grade steel. Although it is more expensive, it is safe and reliable.
Thickness affects strength and quote
Q345 has a characteristic that its yield strength decreases as the plate thickness increases. For plates below 30mm, and for plates above 40mm, if they are of the same material grade, their performance indicators are different.
When quoting, manufacturers often determine the price based on the thickness range. The thicker the plate, the more difficult it is to roll, the longer the production cycle, and the cost will of course be higher. When thick plates are riveted and welded, the man-hours required will also be longer, and these conditions will be reflected in the final price.
How is Q345 better than Q235?
Q345 belongs to the category of low-alloy high-strength steel, with the addition of alloying elements such as manganese and vanadium. This is the fundamental reason why it has better performance than Q235 carbon steel. Its yield strength is significantly higher. Q345 thick plate (above 30mm) riveting price , based on this structural part can be made lighter and thinner.
When in a low-temperature environment, Q345 performs far better than Q235. Q235 tends to become fragile and brittle when the temperature is below zero. However, the E-class of Q345 can withstand impacts of minus 40 degrees. This is also the reason why Northern Engineering and cryogenic vessels will regard Q345 as the first choice.
Market price fluctuation patterns
Greatly affected by the cost of raw materials, steel prices fluctuate, and the prices of iron ore and coke fluctuate. Such fluctuations can be directly transmitted to the steel market. When environmental protection policies tend to tighten, steel mills implement production restrictions. At such times, steel prices often rise.
The demand side is also a key factor. When the construction industry is booming, the demand for steel is strong, causing its price to continue to rise. When the economy enters a downward stage, the product has a backlog of inventory, which causes the price to fall accordingly. In addition, the output volume of thick plate products above 30mm is relatively small, so the price fluctuations are more significant compared with ordinary plates.
How to calculate the cost of riveting and welding processing
The cost of riveting and welding processing is generally calculated based on working hours or based on tonnage. Thick plates are more difficult to weld. They require preheating and heat treatment after welding. All of these processes will increase costs. The consumption of welding materials is much higher than that of thin plates.
There are great differences in the processing complexity of different structures. The amount of labor required for a simple spliced structure and a complex frame structure is completely different. It is best to provide detailed drawings before quoting, so that the manufacturer can make an estimate based on the actual process, so as to avoid disputes about additional items in the later stage.
What to pay attention to when purchasing
When purchasing, it is necessary to clearly clarify the grade of materials required and the impact temperature. Do not place an order hastily just by mentioning Q345. Among them, the riveting price of Q345 thick plate (above 30mm) , there is a price difference between grade A and grade E, and the difference is as much as several hundred yuan per ton. If you choose the wrong level, it will not only cause a waste of funds, but also pose security risks.
Thickness tolerances and surface quality must also be clearly agreed in the contract. The negative deviation of thick plates occasionally appears to be too large. When receiving the actual goods, you need to use calipers to measure it. Once problems are discovered, you must immediately communicate and deal with them to prevent coordination problems during installation.
After reading so much, do you know what grade of Q345 thick plate you need? Tell us about your project requirements in the comment area to help you analyze the selection suggestions.
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