Material issue

Q235 indicates that the yield strength of this steel is 235 MPa. Q235-AF denotes grade A boiling steel, which is commonly used in the manufacture of pressure vessels. This post was last edited by wwxxss_1 on 2009-3-6 at 11:28

Q235 ordinary carbon structural steel – plain plate is a type of steel material. Q represents the yield strength of this material, and the 235 that follows indicates that the yield strength is around 235. And its yield value decreases as the thickness of the material increases. Q235A，Q235B，Q235C，Q235D。 This is a distinction based on grades; what it represents is mainly the difference in the temperature of the impact! What differs among A, B, C, and D is the impact temperature of their properties. They are respectively: Q235A grade, which does not require impact testing ； Grade Q235B: impact at 20 degrees Celsius ； Grade Q235C: impact at 0 degrees ； Grade Q235D: impact at -20 degrees Celsius. At different impact temperatures, the values of impact also vary. Element content: A, B, C, D; the sulfur content decreases in sequence ； A and B have the same phosphorus content; C has a lower phosphorus content, while D has the lowest phosphorus content. The chemical composition of various grades of Q235: Q235 is divided into four grades – A, B, C, and D (GB700-88). Grade Q235A contains 0.14–0.22% carbon, 0.30–0.65% manganese, Si≤0.30, S≤0.050, and P≤0.045. Grade Q235B contains 0.12–0.20% carbon, 0.30–0.670% manganese, Si≤0.30, S≤0.045, and P≤0.045. Grade Q235C contains ≤0.18% carbon, 0.35–0.80% manganese, Si≤0.30, S≤0.040, and P≤0.040. Grade Q235D contains ≤0.17% carbon, 0.35–0.80% manganese, Si≤0.35, S≤0.040, and P≤0.035. In terms of deoxidation methods, these can be represented by F, b, and z, referring to boiling steel, semi-killed steel, and killed steel respectively. Boiling steel is steel with incomplete deoxidation, and it has poor plasticity and toughness. Welded structures made of this material are prone to cracks at the joints under dynamic loads. It is not suitable for operation at low temperatures, and hardening may occur sometimes. In contrast, calm steel has excellent and uniform quality, with good plasticity and toughness. This post was last edited by hwindforce on 2009-3-6 14:25]

1. In Amendment No. 1 to GB150, \"Steel Pressure Vessels\", issued on April 16, 2002, the steel grades Q235-A.F and Q235-A are no longer recommended due to issues with their specifications. (Repost) 2. The scope of application for Q235 - AF is containers with a design pressure of less than or equal to 0.16 MPa, a design temperature ranging from 0 °C to 250 °C, a shell thickness of less than 12 mm, and that do not contain flammable or toxic substances ； Q235A is suitable for containers with a design pressure of 1.10 MPa or less, a design temperature ranging from 0 °C to 350 °C, a shell thickness of less than 16 mm, and those that do not contain liquefied petroleum gas or toxic substances. 3. Q235 is a low-carbon steel; Q235 - AF denotes grade A boiling steel, while Q235 - A refers to low-carbon steel with a carbon content of 0.14–0.22%.