Roundness: mainly for the circular cross-section rolled products, such as the cross section round and round steel pipe, unequal diameters in all directions.

Because of the pre-weld own characteristics, in the back of the welding operations, there often produce tumors, burn, wrong side, solder partial, broken weld (broken arc), weld reinforcement is too low or too high, porosity and slag and other defects. Among them burn, broken weld (broken arc) more likely to be found to take timely repair welding, generally does not have a significant impact on the internal and external welding quality.

NONDESTRUCTIVE TESTING METHODS An NDT method is classified according to its underlying physical principle.

Mild steel consists of iron alloyed with less than 0.3 percent carbon, most commonly between 0.1 to 0.25 percent. The building industry frequently uses mild steel pipe in construction because of its ductility and malleability.

Welding residual stress refers to weldments in the welding process, the thermal stress, transformation stress, machining stress exceeds the yield limit (Yield strength), so that after cooling left weldment fails to eliminate the stress.

Deformation by a principle known thermal processing, when thermal processing, high temperature produced compression deformation due to the heating temperature is uneven, the parts of the contract is also by other parts of the (low-temperature cooling zone or the first part) blocking when cooling, resulting in a variety of residual stresses and distortion.

Because the tube is low intensity, 400 ℃ following is basically no plastic, when the tensile stress exceeds the tensile strength of steel, weld cold cracking occurs.

Iron and steel industry is the basic industry of the national economy, which is the national economic level and an important indicator of overall national strength, the steel industry directly affects the development of the defense industry and its associated buildings, machinery, shipbuilding, automobiles, home appliances and other industries. However, to some extent, steel pipe price will also affect the mobilization of relevant industries a price volatility.

Other countries and ISO stainless steel standards are provided for hot-rolled (forged) steel, in addition to heating pressure processing steel, the general heat treatment delivery (heat treatment requirements need to be specified in the contract).

Aluminum alloy quenching furnace is heated in hood and mobile undercarriage component.

Slab dishing factors and improvement measures mainly in the following areas:

Skew rolling flaring wall-expanding process, extending coefficient of 1. In the event of the main deformation, inevitably be some extra additional deformation.