塑性 塑性是指金屬材料在載荷作用下，產生塑性變形（永久變形）而不破壞的能力。

Plastic plasticity refers to the ability of a metal material to undergo plastic deformation (permanent deformation) without failure under load.

硬度 硬度是衡量金屬材料軟硬程度的指針。目前生產中測定硬度方法常用的是壓入硬度法，它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，根據被壓入程度來測定其硬度值。

Hardness is a pointer that measures the softness and hardness of a metal material. At present, the most commonly used hardness measurement method in production is the Indentation hardness method, which uses an indenter with a certain geometric shape to press into the surface of the metal material to be tested under a certain load, and determines its hardness value according to the degree of indentation.

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。

The commonly used methods include Brinell hardness (HB), Rockwell hardness (HRA, HRB, HRC), and Vickers hardness (HV).

疲勞 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載荷下工作的，在這種條件下零件會產生疲勞。

The strength, plasticity, and hardness discussed earlier on fatigue are all indicators of the mechanical properties of metals under static load. In fact, many machine parts operate under cyclic loads, which can lead to fatigue.

沖擊韌性 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。

Impact toughness refers to the load applied to the machine at a high speed, which is called impact load. The ability of metals to resist damage under impact load is called impact toughness.

強度 強度是指金屬材料在靜荷作用下抵抗破壞（過量塑性變形或斷裂）的性能。由于載荷的作用方式有拉伸、壓縮、彎曲、剪切等形式，所以強度也分為抗拉強度、抗壓強度、抗彎強度、抗剪強度等。各種強度間常有一定的聯系，使用中一般較多以抗拉強度作為基本的強度指針。

Strength refers to the resistance of metal materials to failure (excessive plastic deformation or fracture) under static load. Since the Mode of action of load includes tension, compression, bending, shear and other forms, the strength is also divided into tensile strength, compressive strength, Flexural strength, shear strength and so on. There is often a certain connection between various strengths, and in use, tensile strength is often used as the most basic strength indicator.

方管的用途有建筑，機械制造，鋼鐵建設等項目， 造船，太陽能發電支架，鋼結構工程，電力工程，電廠，農業和化學機械，玻璃幕墻，汽車底盤，機場,鍋爐建造，高速路欄桿，房屋建筑，壓力容器，石油儲罐，橋梁，電站設備，起重運輸機械及其他較高載荷的焊接結構件等。

The square tube is used for building, machinery manufacturing, steel construction and other projects, shipbuilding, solar power generation support, steel Structural engineering, power engineering, power plant, agricultural and chemical machinery, glass curtain wall, automobile chassis, airport, boiler construction, highway railings, housing construction, pressure vessels, oil tanks, bridges, power station equipment, lifting and transportation machinery and other high load welding structural parts.