Mechanical Properties of Materials

We should probably start by admitting that the list of mechanical properties is pretty long. Some are more important and common than others, when describing a material. Therefore, we are looking at the topic from an engineer’s perspective. He needs to know the basics to differentiate金属类型from one another to make an informed decision when designing something.

物质压力和应变

First, we need to explain some of the physical concepts behind the mechanical properties. The main one isstress。压力告诉您，力的大小适用于该区域。在机械工程中，它主要以MPA或N/mm表示²。这两个是可以互换的。压力的公式是：

σ=F/A, where F is force (N) and A is area (mm²).

第二个重要概念是strain。应变没有单位，因为它是长度的比例。计算如下：

ε=(l-l₀）/l₀, where l₀is starting or initial length (mm) and l is stretched length (mm).

Young’s Modulus

From those two concepts we get to our first mechanical properties –刚性and弹性相反。在解决物理问题时，这是工程师的重要因素（对某些应用的物质适用性）。

Stiffness is expressed as Young’s modulus, also known as modulus of elasticity. As one of the primary mechanical properties of materials, it defines the relationship between stress and strain – the bigger its value, the stiffer the material.

这意味着，如果Young的模量有所不同，相同的负载将变形两个同等大小的零件。同时，较小的价值意味着材料更具弹性。

The formula for Young’s modulus:

E=σ/ε (MPa)

Yield Strength

屈服应力或屈服强度是工程计算中最常使用的值。它使材料在MPA中具有应力值，在塑性变形之前可以采用。这个地方称为屈服点。在此之前，材料在抬高负载时会恢复其以前的形状。超过屈服点后，变形为永久性。

There is a good reason for using yield stress as the most important factor in mechanical engineering. As can be seen from thestress-strain curve，当压力超出屈服点时，损害还没有灾难性。在建筑完全失败之前，这留下了“缓冲”。

抗拉强度

最终的拉伸强度或者只是抗拉强度,下一步yield strength. Also measured in MPa’s, this value indicates the maximum stress a material can withstand before fracturing.

When choosing a suitable material to tolerate known forces, two materials with a similar yield strength may have different tensile strengths. Having higher tensile strength may help to avoid accidents, if unforeseen forces are applied.

Plasticity

Plasticity is a mechanical property of materials that shows the ability to deform under stress without breaking, while retaining thedeformedshape after the load is lifted. Metals with higher plasticity are better for forming. This is evident inmetal bending。

材料的两个相关机械性能是延性and锻造性。延展性与可塑性的描述几乎相似 - 这是材料在破裂前经历塑性变形的能力。它表示为伸长百分比或降低面积百分比。例如，延展性是在绘制细金属线时所需的属性。这样的延性材料的一个很好的例子是铜。This makes the fabrication of wires possible.

Malleability is, by definition, also similar. But it actually characterises a material’s suitability for compressive deformation. In essence, a metal with good malleability is fitting for producing metal plates or sheets by rolling or hammering.

韧性

韧性是强度和可塑性的结合。坚韧的材料可以不破裂而进行艰苦的打击。韧性通常被定义为材料在不破裂而不破裂的情况下吸收能量的能力。

所需韧性的一个例子是采石装载机。如果材料坚硬，将巨大的岩石扔进垃圾箱会导致变形，而不是裂缝。

Hardness

工程材料的另一个重要属性。高的hardness valuesshow that a material resists localised pressures. In simple terms, a hard material is not easy to scrape or punctuate with lasting marks (plastic deformation). It is especially important when heavy磨损过程take place. In such circumstances, hard materials likeHardox合适。硬度和韧性是两个解释的特质耐用性。

Hardness is measured by scratching, bouncing or indentation. The most common way to describe hardness is through indentation hardness. There are different ways to carry out these tests, depending on the material. Each results in a different hardness unit – Brinell, Vickers or Rockwell. If you want to compare 2 materials that have hardness values in different systems, you have to convert them to the same type (e.g Vickers) first.

Brittleness

Brittleness is usually quite an unwanted material property in mechanical engineering. It means that a material breaks without noticeable plastic deformation. An indication of a material’s brittleness is the snapping sound it makes when breaking.

尽管在考虑脆性时，它可能与低强度有关，但实际上并非如此。这两个不是互斥的。坚固的材料仍然可以脆弱。一个例子就是陶瓷。铸铁是脆性金属的一个例子。

疲劳强度

Fatigue strength, or fatigue limit，表达材料承受的能力循环应力。的情况下ferrous alloys，金属可以抵抗的明显限制。如果压力低于极限（根据周期的数量），则不必担心破裂。

在设计轴时要记住这是一个重要的材料属性。力的方向随着轴的旋转而不断变化，这意味着应力是周期性的。

With other metals, likealuminium和铜，周期性应力抗性没有明显的限制。他们仍然倾向于在一定量之后破裂reversed bending stress。For such materials, there is another similar measurable value –耐力力量。

如果应力值低于疲劳极限，则具有疲劳强度，具有无限的寿命。在具有耐力强度的情况下，您将获得一个值，低于该材料可以为一定数量的循环工作。通常设置为10⁷。

我f you have made an informed decision about your material selection, it is time for manufacturing. We are here to help you with在线制造服务呢