Technical Information

Effects of Alloy Elements

In order to provide their unique properties which cannot normally be obtained from carbon steels, steels made by adding one or more alloying elements are alloyed steels.

The effect of alloy elements is most effective in steel structure compared to other metals.Moreover, since the effects of alloying elements cannot be collected, the expected changes in properties can only be considered in the general framework if a large number of alloying elements are present.

Alloyed steels are divided into two main groups as low alloy steels and high alloy steels. The total amount of alloy elements (other than carbon and non-refractory elements) is called low-alloy steels to those with less than 5%.The total amount of alloy elements is higher than 5% and is called high alloy steels.The most important characteristic of low alloy steels with similar behavior to non-alloyed steels is their higher hardening ability. In addition, the properties such as hardness, tensile strength, yield limit, elasticity modulus and heat resistance, tempering resistance are increased. Generally, the values such as elongation at break, section narrowing, notch impact resistance are reduced. Unalloyed and low-alloyed steels are used in the absence or inadequacy of high-alloy steels. This type of alloying, besides increasing the mechanical strength at normal temperatures, aims at obtaining some desirable properties, in particular heat, scale and corrosion resistance, temperature hardness and non-magnetization.

Stainless Steel Types

In the case of stainless steels, different properties can be obtained by changing the chemical composition. The most important alloying elements are Iron, Chrome, Nickel, Mobilden and Manganese. According to the proportions of these elements, mainly stainless steel types are collected in five main groups.
Austenitic steels Ferritic steels Martensitic steels Duplex steel Stainless steels that can be hardened by precipitation

Austenitic steels are the most commonly used steels and their main composition is 16-26% chromium, max 35% nickel and 0,40% carbon.Although there are 200, 300 and 304 series, 304 is the most commonly used. Belirgin özelliği nonmanyetik olmaları ve sertleştirme ısıl işlemi uygulanamaz olmalarıdır. Their share in the total stainless family is about 70%. Its main areas of application are machine manufacturing, chemical plants, kitchenware and decoration.Below are the nominal chemical analysis values of austenitic steels.

Ferritic stainless steels are non-hardenable Fe-Cr alloys.Maximum steel up to 0,20%, chromium containing 11-30% chromium. The most prominent feature is that they are magnetic and they show faster corrosive properties in humid environments. The main applications are kitchen utensils, auto parts, exhaust elements and hot water boilers.Below, nominal chemical analysis values of ferritic stainless steels are listed.

Martensitic stainless steels, carbon ratio up to 1.2%, chromium is 11-18% of the steel are. The most important feature is that they are subjected to hardening heat treatment. Its main applications are cutting tools. The nominal chemical analysis values of standard and non-standard martensitic steels are listed below.

Duplex stainless steels, chromium ratio of 18-28%, nickel ratio is in the range of 5-8%. This group of steel generally contains 2-4% mobile, besides the good strength properties, they are ductile.Main fields of application are chemical equipment manufacturing and marine equipment. Stainless steels that can be set by precipitation; It contains alloying elements which allow to harden to steel by heat treatment such as aluminum and solidification (precipitation). These steels are also subdivided into martensitic, semi-austenitic, austenitic precipitation steels.