低合金结构钢是指合金总成分小于5%的合金结构钢。这种钢的碳含量类似于低碳钢,并且主要通过少量合金元素来增强其碳含量,以提高韧性和可焊性。它的强度远高于相同的碳素钢。广泛用于压力容器,化工设备,锅炉,桥梁,车辆,船舶和大型钢结构。锰,硅和钼等合金元素会导致固溶强化。钒和铌可以细化晶粒并提高韧性。钼可以改善淬透性,贝氏体组织和热强度。

什么是低合金结构钢2

品牌及其代表

Low alloy structural steel grades and their expression: there are five grades of low alloy structural steel in China, and the main elements are manganese, silicon, vanadium, titanium, sharp, chromium, nickel and rare earth elements. Its trademark is composed of yield point letter Q, yield point value and quality grade (Grade A, B, C, D, e). It is divided into five grades, which are expressed as follows: yield point grade – quality grade. Yield point grade: q295, Q345, Q390, Q420, Q460.

什么是低合金结构钢3

性能要求

1.良好的综合机械性能。普通的低合金结构钢起初应具有较高的屈服极限,但由于其工作条件的复杂性,还应具有良好的综合力学性能。例如,它可以承受使用中的各种应力(例如温差应力,交替疲劳载荷产生的应力等)的影响,并且可以承受加工过程中的剪切,冷弯,焊接等加工程序。制造过程,以及由此产生的老化脆性。

2.良好的工艺性能。要求普通的低合金钢应具有良好的加工成型性能,并采用剪切,冲压,热弯,焊接等常用方法制造出优质的成品。对于锅炉,压力容器,钢结构等,一般采用焊接方法,因此钢应具有良好的火焰切割性能和焊接性能,焊缝附近热影响区的性能变化较小,焊缝及其部位相邻区域不得产生裂纹,且焊接接头的综合机械性能不得小于(或很少小于)母材。另外,要求钢具有良好的冷冲压性能。

3.良好的耐腐蚀性。由于普通低合金钢及其强度远高于碳钢,并且压力容器和由其制成的钢结构的壁厚比碳钢小,因此大气腐蚀(尤其是海洋大气腐蚀)造成的损失率因此,必须提高其抗腐蚀能力,以便在各种大气条件下具有良好的抗腐蚀能力。因此,不仅应在实验室中而且还要在现场进行钢的耐蚀性测试。当然,对于碳素钢,低合金钢和其他材料,必须采用适当的外部防腐技术。

什么是低合金结构钢4

合金元素的作用

The common low alloy steel widely used in pressure vessel is mostly ferrite pearlite structure. The final properties are obtained by hot rolling or normalizing, and its structure is accepted by the equilibrium structure of steel. The main alloy element in steel is carbon. Increasing the carbon content can increase the quantity of pearlite and increase the yield limit and strength limit. However, there is a certain limit to increase the carbon content, because the increase of carbon content will affect the welding performance and other properties of steel (such as stamping performance, etc.), so that the brittleness transition temperature increases and the cold brittleness goes bad. Therefore, the carbon content of low alloy structural steel for pressure vessels is generally limited to less than 0.20%. When the carbon content is limited, the increase of the strength of this kind of steel mainly depends on the addition of a small amount of various alloy elements (the total addition is less than 5%, generally less than 3%, mostly 1% – 2%). For the low alloy structural steel with ferrite pearlite structure, the effects of adding alloy elements on its strength are as follows:

①相同溶液强化铁素体;

②增加珠光体的相对含量;

③控制晶粒尺寸;

④影响珠光体的分散;

⑤沉淀硬化。

锰和硅都固溶于铁素体中,具有明显的固溶强化作用。其他元素包括铬,镍,铜,钴等。考虑到节省成本和节约资源的条件,锰和硅是中国低合金钢中常用的合金元素。在低碳的条件下,当锰含量小于1.8%时,不仅可以提高钢的强度,而且可以保持可塑性和韧性。另外,锰可以扩大奥氏体区并使钢的共析点向左和向下移动,从而使它具有更多的珠光体组织和更细的结构,并相应地提高了钢的强度。

The silicon content in low alloy structural steel is generally in the range of 0.2% – 1.7%, which will reduce the toughness. Chromium and nickel are also solid solution strengthening elements of ferrite, and nickel has a good effect on improving low temperature toughness; phosphorus strengthening ferrite has a significant effect, but due to the increase of cold brittleness, the maximum content should be limited to 0.15%, and the total content of phosphorus and carbon should be limited to less than 0.25%.

应用

根据国家标准(低合金高强度结构钢)(GB 1591),规定了每种等级的低合金高强度结构钢的化学成分和力学性能。低合金结构钢由于合金元素的强化作用,不仅具有较高的强度,而且具有较好的可塑性,韧性和可焊性。 Q345钢具有良好的综合性能,是钢结构的通用品牌。 Q390等级也是推荐的品牌。与碳素结构钢Q235相比,低合金高强度结构钢可以节省20%〜30%钢,并具有良好的动载荷和抗疲劳性。低合金结构钢主要用于轧制各种型材,钢板,钢管和钢筋。它广泛用于钢结构和钢筋混凝土结构,尤其是各种重型结构,大跨度结构,高层结构和桥梁工程,承受动态和冲击载荷的结构等。

低合金结构钢是一种低碳结构钢。合金元素含量小于3%,主要用于细化晶粒,提高强度。这种钢的强度明显高于相同碳含量的碳钢,因此通常被称为低合金高强度钢。它还具有良好的韧性,可塑性,可焊接性和耐腐蚀性。最初用于桥梁,车辆,轮船等行业,其应用范围已扩展到锅炉,高压容器,油管,大型钢结构,汽车,拖拉机,土方机械等产品。