無縫異型鋼管的生產(chǎn)分類與規(guī)格類型：無縫異型管是將帶鋼擠壓成型而成。塑性是指金屬材料在載荷作用下，產(chǎn)生塑性變形(永久變形)而不破壞的能力。硬度是衡量金屬材料軟硬程度的指針。目前生產(chǎn)中測定硬度方法最常用的是壓入硬度法，無縫異型鋼管是用一定幾何形狀的壓頭在一定載荷下壓入被測試的金屬材料表面，根據(jù)被壓入程度來測定其硬度值。

Production Classification and Specification Type of Seamless Special-shaped Steel Pipe: Seamless Special-shaped Steel Pipe is formed by extrusion of strip steel. Plasticity refers to the ability of metal materials to produce plastic deformation (permanent deformation) without destroying under load. Hardness is the index to measure the degree of hardness and softness of metal materials. Pressure hardness method is the most commonly used method to measure hardness in production. Seamless special-shaped steel pipe is pressed into the tested metal material surface with a certain geometric shape of the pressure head under a certain load, and its hardness value is measured according to the degree of pressure. 常用的方法有布氏硬度(HB)、洛氏硬度(HRA、HRB、HRC)和維氏硬度(HV)等方法。前面所討論的強度、塑性、硬度都是金屬在靜載荷作用下的機械性能指針。實際上，許多機器零件都是在循環(huán)載荷下工作的，在這種條件下零件會產(chǎn)生疲勞。以很大速度作用于機件上的載荷稱為沖擊載荷，金屬在沖擊載荷作用下抵抗破壞的能力叫做沖擊韌性。

Common methods include Brinell hardness (HB), Rockwell hardness (HRA, HRB, HRC) and Vickers hardness (HV). The strength, plasticity and hardness discussed above are all mechanical performance indicators of metals under static loads. In fact, many machine parts work under cyclic loads, under which fatigue occurs. The load acting on the machine parts at a great speed is called impact load, and the ability of metal to resist damage under impact load is called impact toughness.