生產(chǎn)無縫異型鋼管所用的坯料，叫做管坯，合格的管坯是無縫異型鋼管生產(chǎn)的先決條件。由于斜軋穿孔的變形特點(diǎn)，對管坯質(zhì)量（尤其是表面質(zhì)量）提出了以下嚴(yán)格的技術(shù)要求：

The blank used to produce seamless special-shaped steel pipe is called tube blank. Qualified tube blank is a prerequisite for the production of seamless special-shaped steel pipe. Due to the deformation characteristics of cross-rolling piercing, the following strict technical requirements are put forward for the quality of billet (especially the surface quality): （一）管坯直徑過大或橢圓度過大，會(huì)使無縫異型鋼管穿孔時(shí)咬入條件變壞，還會(huì)因管坯直徑壓縮量過大而促使內(nèi)折的發(fā)生；

(1) If the diameter of billet is too large or the ellipticity is too large, the biting condition of seamless special-shaped steel pipe will be worsened when it is perforated, and the internal folding will occur because of the excessive compression of the diameter of billet;

（二）管坯的表面質(zhì)量十分重要，因?yàn)樵诠芘鞲叭魏螝堈隙际袔У街破?a href="http://m.emudi.cn" title="無縫異型鋼管" target="_blank" class="sitelink">無縫異型鋼管上，并且有殘障的地點(diǎn)頻頻會(huì)釀成應(yīng)力集中，通過塑性變形將使殘障加深、加長；

(2) The surface quality of the billet is very important, because the billet is brought to the seamless special-shaped steel pipe in any disabled city, and the place where the billet is disabled often results in stress concentration, which will deepen and lengthen the disability through plastic deformation.

（三）內(nèi)部組織緊要是指縮孔和中央疏松，非金屬夾雜的積累、氣體的含量等。這種要求的嚴(yán)格程度，隨無縫異型鋼管的用途和鋼種的差異而異；

(three) internal organization is closely related to shrinkage porosity and central porosity, accumulation of non-metallic inclusions, and gas content. The strictness of this requirement varies with the use of seamless profiled steel pipe and the difference of steel grades.

（四）要對無縫異型鋼管坯進(jìn)行顯微組織的檢驗(yàn)，以測定非金屬夾雜物（如硫化物、氧化物及碳化物）的含量及分布形態(tài)，鑒別帶狀組織與脫碳層等；

(4) The microstructures of seamless special-shaped steel tube blanks should be examined to determine the content and distribution of non-metallic inclusions (such as sulphides, oxides and carbides), and to identify the banded structure and decarbonization layer.

（五）為了擔(dān)保穿孔過程的合理進(jìn)行和獲得高質(zhì)量的無縫異型鋼管，必需對管坯的幾何尺寸，低倍組織和表面狀態(tài)等提出嚴(yán)格的要求；

(5) In order to ensure the reasonable piercing process and obtain high quality seamless special-shaped steel tubes, strict requirements must be put forward on the geometric size, macrostructure and surface state of the billet.

（六）無縫異型鋼管坯的低倍組織不應(yīng)有肉眼可見≥1級的殘余縮孔、翻皮、分層、氣泡、砂眼、非金屬夾雜、白點(diǎn)及裂紋等。

(6) The macrostructure of the seamless special-shaped steel tube blank should not be visible to the naked eye as residual shrinkage, skin turning, delamination, bubbles, sand holes, non-metallic inclusions, white spots and cracks, etc.