我们要从辩证的角度来理解，主要体现在加热阶段和结晶阶段。
We should understand it dialectically, which is mainly reflected in the heating stage and crystallization stage. 加热阶段Heating stage 在工作状态下，高频直缝焊管的管坯边缘从室温加热到焊接温度。
在此期间，管坯边缘完全暴露在空气中，没有任何保护，这不可避免地与空气中的氧气和氮气有关。
发生剧烈反应，显着增加焊缝中的氮和氧化物。
据测量，焊缝中的氧含量增加7～35倍，氮含量增加20～45倍；同时，有利于焊接。
大量的锰、碳等合金元素烧尽蒸发，降低了焊缝的力学性能。
这样可以看出，焊接速度越慢，焊接质量越差。
In the working state, the billet edge of high frequency longitudinal welded pipe is heated from room temperature to welding temperature. During this period, the edge of the tube blank is completely exposed to the air without any protection, which is inevitably related to oxygen and nitrogen in the air. Violent reactions occurred, significantly increasing nitrogen and oxides in the weld. According to the measurement, the oxygen content in the weld increases by 7 ~ 35 times and the nitrogen content increases by 20 ~ 45 times; At the same time, it is conducive to welding. A large number of manganese, carbon and other alloy elements are burned out and evaporated, which reduces the mechanical properties of the weld. It can be seen that the slower the welding speed, the worse the welding quality. 不仅如此，即焊接速度越慢，加热管坯的边缘暴露在空气中的时间越长，会导致更深的层中产生非金属氧化物，这些深层的非金属氧化物将难以用于后续的挤压和结晶过程。
从焊缝完全挤出后，结晶后会以非金属夹杂物残留在焊缝中，降低焊缝的强度，从而破坏焊缝组织的连续性，形成明显的脆性界面。
焊接速度快，从而氧化时间短，产生少量的非金属氧化物，而且仅存在于表层。
在后续的挤压过程中很容易被挤出焊缝，焊缝中不会有太多的非金属，氧化物残留，焊接强度高。
Moreover, the slower the welding speed, the longer the edge of the heated tube blank is exposed to the air, which will lead to the generation of non-metallic oxides in the deeper layer. These deep non-metallic oxides will be difficult to be used in the subsequent extrusion and crystallization process. After fully extruded from the weld, non-metallic inclusions will remain in the weld after crystallization, which will reduce the strength of the weld, destroy the continuity of the weld structure and form an obvious brittle interface. The welding speed is fast, so the oxidation time is short, and a small amount of non-metallic oxide is produced, which only exists in the surface layer. In the subsequent extrusion process, it is easy to be extruded from the weld, and there will not be too many non-metallic in the weld. Oxide residue, high welding strength. 结晶阶段Crystallization stage 为了获得高强度焊缝，根据金属学原理，焊缝组织的晶粒必须尽可能细化，而细化的方式就是在短时间内产生足够多的晶核。
当它们尚未显著长大时相互接触便结束结晶过程。
通过加快焊接速度，让焊缝迅速离开加热区，在过冷度大的情况下迅速结晶；当过冷度增加时，成长率增加较少，生核率能够大大增加，从而达到细化焊缝晶粒的目的。
In order to obtain high-strength weld, according to the principle of metallography, the grain of weld structure must be refined as much as possible, and the way of refinement is to produce enough nuclei in a short time. When they have not grown significantly, they contact each other and end the crystallization process. By accelerating the welding speed, the weld can leave the heating zone quickly and crystallize rapidly under the condition of high undercooling; When the undercooling degree increases, the growth rate increases less, and the nucleation rate can increase greatly, so as to refine the weld grain. 因此，在满足基本焊接条件下，焊接速度越快，质量就越好。
Therefore, under the basic welding conditions, the faster the welding speed, the better the quality.