In the international community, owing to years of unceasing efforts by several countries, particularly the U. S., creating the ERW steel pipe seamless has been a lot of happy with the answer. ERW steel pipe seamless was divided into geometric seamless and physical seamless.
About geometric seamless, its definition is removing the burr of ERW steel pipe on the within and out of doors. because the continuous improvement of the structure of the inner burr removal system and cutting implement, the clearance of the burrs within the massive and medium diameter pipes has been well handled. Burr are often controlled within the -0.2mm ~ O.5mm or so.
Physical seamless implies that the distinction between the metallographic structure within the weld and also the base metal leads to a decrease within the mechanical properties of the weld space. it's necessary to require measures to create it uniform and consistent. The high-frequency attachment method of ERW steel pipe, resulted within the temperature distribution gradient close to the sting of the tube, and fashioned melting zone, semi-melting zone, superheated organization, normalized space, incomplete normalized space, tempered space and alternative characteristic areas. owing to the attachment temperature within the superheated organization is on top of one thousand ℃, the primary solid solution grain grows chop-chop, the laborious and brittle coarse crystalline section is made beneath cooling conditions. additionally, the existence of gradient can manufacture attachment stress. during this method, scenario|things|matters|true|the case} that the weld space of mechanical properties is not up to the bottom metal situation are going to be fashioned. Physical seamless is that the native typical heat treatment method of weld (that is exploitation MF heating device to heat weld region to AC3 (927 ℃)), then proceed the 60m length, the speed of 20m / min air cooling method.If it's necessary, the water cooling are going to be carried. the employment of this methodology has achieved the aim of eliminating stress, softening and purification the structure, and rising the excellent mechanical properties of the warmth affected zone. So far, this methodology has been wide utilized by the world's most advanced ERW unit to contend with the weld, which has achieved smart results. The high-quality ERW steel pipe not solely cannot make out the weld, and also the weld constant will reach to one, achieves the weld space organization and base metal match.