冷拔管和热轧管区别

Difference between cold drawn tube and hot rolled tube

一.热轧

One. Hot rolling

  优点:可以破坏钢锭的铸造组织，细化钢材的晶粒，并消除显微组织的缺陷，从而使钢材组织密实，力学性能得到改善。这种改善主要体现在沿轧制方向上，从而使钢材在一定程度上不再是各向同性体；浇注时形成的气泡、裂纹和疏松，也可在高温和压力作用下被焊合。 

Advantages: it can destroy the ingot casting, steel grain refinement, and eliminate the defects in microstructure, so that steel dense tissue, improved mechanical properties. This improvement is mainly reflected along the rolling direction, so that steel is no longer a certain extent, isotropic body; casting formed when bubbles, cracks and loose, can also be welded under high temperature and pressure.  

  缺点:1.经过热轧之后，钢材内部的非金属夹杂物（主要是硫化物和氧化物，还有硅酸盐）被压成薄片，出现分层（夹层）现象。分层使钢材沿厚度方向受拉的性能大大恶化，并且有可能在焊缝收缩时出现层间撕裂。焊缝收缩诱发的局部应变时常达到屈服点应变的数倍，比荷载引起的应变大得多； 2.不均匀冷却造成的残余应力。残余应力是在没有外力作用下内部自相平衡的应力，各种截面的热轧型钢都有这类残余应力，一般型钢截面尺寸越大，残余应力也越大。残余应力虽然是自相平衡的，但对钢构件在外力作用下的性能还是有一定影响。如对变形、稳定性、抗疲劳等方面都可能产生不利的作用。3.热轧的钢材产品，对于厚度和边宽这方面不好控制。我们熟知热胀冷缩，由于开始的时候热轧出来即使是长度、厚度都达标，最后冷却后还是会出现一定的负差，这种负差边宽越宽，厚度越厚表现的越明显。所以对于大号的钢材，对于钢材的边宽、厚度、长度，角度，以及边线都没法要求太精确。

Disadvantages: 1. after after rolling, steel internal non-metallic inclusions (mainly sulfide and oxide and silicate) were pressed into thin slices, layered (laminated) phenomenon. The layering can greatly deteriorate the tensile properties of the steel along the thickness, and it is possible to tear interlayer tearing when the weld is contracted. The local strain induced by weld shrinkage often reaches several times of yield point strain, much larger than that caused by load, and 2. residual stress caused by non-uniform cooling. The residual stress in the external force is no internal stress self balanced, hot-rolled steel section with the residual stress, general steel section size is larger, the greater the residual stress. Although the residual stress is self - phase equilibrium, it has a certain influence on the performance of steel members under external force. Such as deformation, stability, anti fatigue and other aspects may have adverse effects. 3. hot rolled steel products are not well controlled for thickness and side width. We are familiar with thermal expansion and cold contraction. Since the hot rolled at the beginning, even if the length and thickness are all up to standard, there will be a certain negative difference after cooling. The wider the negative side width is, the thicker the thickness is, the more obvious the performance is. Therefore, for the large steel, the width, thickness, length, angle, and border of the steel are not too precise.

二.冷轧

Two. Cold rolling

      是指在常温下，经过冷拉、冷弯、冷拔等冷加工把钢板或钢带加工成各种型式的钢材。

Refers at room temperature after cold drawing, cold, cold and cold processing of the steel sheet or strip processed into various types of steel.

       优点：成型速度快、产量高，且不损伤涂层，可以做成多种多样的截面形式，以适应使用条件的需要；冷轧可以使钢材产生很大的塑性变形，从而提高了钢材的屈服点。 

Advantages: fast forming speed, high yield, and no damage to the coating can be made into a variety of forms, cross section, in order to meet the needs of the conditions of use; cold rolled steel to produce plastic deformation greatly, thus improving the yield point of steel.  

       缺点:  1.虽然成型过程中没有经过热态塑性压缩，但截面内仍然存在残余应力，对钢材整体和局部屈曲的特性必然产生影响； 2.冷轧型钢样式一般为开口截面，使得截面的自由扭转刚度较低。在受弯时容易出现扭转，受压时容易出现弯扭屈曲，抗扭性能较差； 3.冷轧成型钢壁厚较小，在板件衔接的转角处又没有加厚，承受局部性的集中荷载的能力弱。

Disadvantages: 1. although the molding process without hot plastic compression section, but still existed in the residual stress characteristics of steel overall and local buckling of the inevitable impact; 2. cold rolled steel style is generally open section, the section of the torsional stiffness of the lower. It is prone to torsion when it is subjected to bending. When it is compressed, it is prone to bend, twist and flexure, and its torsion resistance is poor. 3., the cold rolling forming steel has small wall thickness, and it is not thickened at the corner of plate joining, and it is weak to bear local concentrated load.

三.热轧和冷轧的主要区别是： 

Three. The main difference between hot and cold is:

    1、冷轧成型钢允许截面出现局部屈曲，从而可以充分利用杆件屈曲后的承载力；而热轧型钢不允许截面发生局部屈曲。 

1, cold formed steel section allows local buckling, which can make full use of bar buckling bearing capacity; and hot rolled steel does not allow the local buckling of cross section.  

    2、热轧型钢和冷轧型钢残余应力产生的原因不同，所以截面上的分布也有很大差异。冷弯薄壁型钢截面上的残余应力分布是弯曲型的，而热扎型钢或焊接型钢截面上残余应力分布是薄膜型。

The reason residual 2, hot-rolled steel and cold-rolled steel stress are different, so the distribution on the section are quite different. The residual cold-formed steel section stress distribution is curved, and hot rolled steel or steel welding section on the residual stress distribution is thin.

两种钢管在成品上没有多大的区别,一般都是按标准制造的.机械性能都没什么样区别

There is not much difference between the two kinds of steel tubes in finished products. They are generally made according to standard. There is no difference in mechanical properties.

存在的多数是加工工艺不同,以及最后出来的精度不同,一般来讲冷拔尺寸精度及表面光洁度较高.

Most of the existing processing technology is different, and the final accuracy is different, generally speaking, the cold drawing precision and the surface finish are high.

热轧工艺:管坯---加热---穿孔---轧管---定径---冷床---矫直---切管---检验---打包---发货

Hot rolling tube - heating - - perforated tube rolling - sizing - bed - straightening - - - - pipe cutting test package delivery

冷拔工艺:管坯---加热---穿孔----热轧(二穿)等---打头--酸洗--磷化--冷拔--退火(可以多道次重复打头至后工序)---矫直----切管---检验---打包---发货

Cold drawing process: tube billet -- Heating -- piercing -- hot rolling (Er Chuan) and so on -- start up -- acid pickling -- phosphating -- cold drawing annealing, which can be repeated multiple times to the later process -- straightening, cutting and checking -- packing -- shipment.

钢管作为钢铁产品的重要组成部分，因其制造工艺及所用管坯形状不同而分为无缝钢管（圆坯）和焊接钢管（板，带坯）两大类。

As an important part of iron and steel products, the steel pipe is divided into two main categories: seamless steel tube (round billet) and welded steel pipe (slab and billet) because of its manufacturing process and the shape of tube blank.

（1）无缝钢管

(1) seamless steel pipe

因其制造工艺不同，又分为热轧（挤压）无缝钢管和冷拔（轧）无缝钢管两种。冷拔（轧）管又分为圆形管和异形管两种。

Because of its different manufacturing process, it is divided into two kinds of hot rolling (extrusion) seamless steel pipe and cold drawn (rolling) seamless steel pipe. The cold drawing (rolling) tube is divided into two kinds of circular tube and special tube.

a．工艺流程概述

Overview of A. process flow

热轧（挤压无缝钢管）：圆管坯→加热→穿孔→三辊斜轧、连轧或挤压→脱管→定径（或减径）→冷却→坯管→矫直→水压试验（或探伤）→标记→入库。

Hot rolled (extruded seamless steel pipe): round tube billet, heating, piercing, three roll skew rolling, continuous rolling or extrusion, pipe stripping, diameter setting or reducing, cooling to blank tube to straightening, water pressure test (or flaw detection), marking to storage.

冷拔（轧）无缝钢管：圆圆管坯→加热→穿孔→打头→退火→酸洗→涂油（镀铜）→多道次冷拔（冷轧）→坯管→热处理→矫直→水压试验（探伤）→标记→入库。

Cold drawn (rolled) seamless steel tube: round tube billet, heating, piercing, heading to annealing, acid pickling, oiling (copper plating), multi pass cold drawing (Leng Zha), tube to heat treatment, straightening, water pressure test, marking to storage.