塑性 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。

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(chǎn)中測(cè)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(cè)試的金屬材料表面，根據(jù)被壓入程度來測(cè)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(qiáng)度、塑性、硬度都是金屬在靜載荷作用下的機(jī)械性能指針。實(shí)際上，許多機(jī)器零件都是在循環(huán)載荷下工作的，在這種條件下零件會(huì)產(chǎn)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(jī)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(qiáng)度 強(qiáng)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(qiáng)度也分為抗拉強(qiáng)度、抗壓強(qiáng)度、抗彎強(qiáng)度、抗剪強(qiáng)度等。各種強(qiáng)度間常有一定的聯(lián)系，使用中一般較多以抗拉強(qiáng)度作為基本的強(qiáng)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(jī)械制造，鋼鐵建設(shè)等項(xiàng)目， 造船，太陽能發(fā)電支架，鋼結(jié)構(gòu)工程，電力工程，電廠，農(nóng)業(yè)和化學(xué)機(jī)械，玻璃幕墻，汽車底盤，機(jī)場(chǎng),鍋爐建造，高速路欄桿，房屋建筑，壓力容器，石油儲(chǔ)罐，橋梁，電站設(shè)備，起重運(yùn)輸機(jī)械及其他較高載荷的焊接結(jié)構(gòu)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.