It has good comprehensive performance, low temperature performance, cold stamping performance, welding performance and processability. Widely used in bridges, vehicles, ships, buildings, pressure vessels and so on.
Q represents the yield of this material, and the latter 345 refers to the yield value of this material, which is about 345MPa. And the yield value will decrease with the increase of material thickness.
Extended data
I. Tool steel
1, and the steel grade is marked with "t" to avoid mixing with other steel grades.
2. The number in the steel grade indicates the carbon content, which is expressed by a few thousandths of the average carbon content. For example, "T8" means that the average carbon content is 0.8%.
3. If the manganese content is high, mark "Mn" at the end of the steel grade, such as "T8Mn".
4. The phosphorus and sulfur content of high-quality carbon tool steel is lower than that of ordinary high-quality carbon tool steel. Add the letter "a" at the end of the steel number to show the difference, such as "T8MnA".
Second, free-cutting steel.
1, and the steel grade is marked with "y" to distinguish it from high-quality carbon structural steel.
2. The number after the letter "Y" indicates the carbon content, which is expressed as a few ten thousandths of the average carbon content. For example, the free-cutting steel with an average carbon content of 0.3% has a brand name of "Y30".
3. If the manganese content is high, mark "Mn" after the steel grade, such as "Y40Mn".
References:
Baidu encyclopedia -Q345b