What is the difference between A3 steel pipe and Q235 steel pipe?

What is an A3 steel pipe

First of all, A3 steel pipe is the name of the past, although it is still in use, but it is limited to spoken language, it is no longer used in written documents, it is a class A steel pipe, it is a carbon steel pipe with a low carbon content, of which a represents the mechanical properties of steel pipe, a3 is a grade in the steel pipe standard, which is the old standard GB/T700. This type of steel pipe manufacturers only guarantee mechanical properties and do not guarantee the chemical composition when they leave the factory, so the impurity components such as S and P may be a little more, and their carbon content is about 0.2%, which is roughly equivalent to the No. 20 steel pipe, which is comparable to the new standard Q235. This type of steel pipe is the most widely used one, due to the moderate carbon content, in terms of strength, plasticity and weldability and other aspects of the better fit, from the comprehensive performance is more excellent. Of course, the title of a3 steel pipe is no longer used in the written materials now, but in people who have become accustomed to using the old standard, they still use this statement in the habit, so there are often new people who do not understand what the teacher often says about the a3 steel pipe.

Q235 steel pipe introduction
Q235 steel pipe is a kind of carbon structural steel pipe. Q represents the yield limit of this material, and the 235 in the back refers to the yield value of this material, which is around 235MPa. Usually, the steel pipe is used directly without heat treatment. It consists of Q+ number + mass grade symbol + deaeration method symbol. Its steel pipe number is crowned with “Q”, which represents the yield point of the steel pipe, and the number after it represents the yield point value, and the unit is MPa, such as Q235, which represents the yield stress (σs) of carbon structural steel pipe with a yield stress of 235 MPa. If necessary, the pipe number can be followed by a symbol indicating the quality level and deoxidation method. The quality class symbols are A, B, C, and D. Deoxidation method symbol: F means boiling steel pipe; b means semi-calm steel pipe: Z means calm steel pipe; TZ means a special calming steel pipe, and the calming steel pipe can be unmarked, that is, Z and TZ can be unmarked. For example, Q235-AF represents a class A boiling steel pipe.

Q235A, B, C, D What is the difference

GB/T 700-2006 standard carbon structural steel pipe Q235 according to metallurgical quality is divided into A, B, C, D four grades, the chemical composition of each grade of steel pipe is: Q235A, B, C, D four grades (GB/T 700-2006), in turn to A grade quality is poor, D grade quality is the highest. The sulfur content of A, B, C and D decreases sequentially; Phosphorus content of A and B is the same, followed by phosphorus content of C, D phosphorus content is at least Q235A grade contains C 0.14-0.22% Mn 0.30-0.65% Si ≤0.30% S ≤0.050 P ≤0.045Q235B contains C 0.12-0.20% Mn 0.30-0.70% Si ≤0.30% S ≤0.045 P ≤0.045Q235C contains C ≤0.18% Mn 0.35-0.80% Si ≤0.30% S ≤0.040 P ≤0.040Q235D class contains C ≤0.17% Mn 0.35-0.80% Si ≤0.30% S ≤0.035 P ≤0.035Q235A, Q235B, Q235C, Q235D Different grades represent, mainly the impact temperature is different. A refers to not doing impact, B is above 20 degrees, C is above 0 degrees, D-20 degrees or more, A to E is different, referring to the difference in their performance of the impact temperature. Respectively: Q235A class, is not required for impact toughness test; Q235B grade, is used for normal temperature (20 °C) impact toughness test; Q235C grade, is for 0 °C impact toughness test; Q235D grade, is for -20 °C impact toughness test.