Alloy steel: Properties, processing and leading Indian producers - BigMint analysis

Alloy steels represent a crucial segment of the steel industry, offering enhanced properties beyond those of regular carbon steel. These materials are created by combining carbon steel with various alloying elements such as manganese, silicon, nickel, titanium, copper, chromium, and aluminum. The specific combination and proportions of these elements dictate the resulting properties, including increased hardness, corrosion resistance, strength, formability (ductility), and weldability.

Capacity and production

The Indian alloy steel sector has an installed capacity of approximately 11.5 million tonnes (mnt), while the actual production hovers around 7 mnt. This indicates a capacity utilisation rate of roughly 61-70%, leaving a significant portion of the potential output untapped. Despite this underutilisation, the alloy steel industry holds substantial value, accounting for a notable share of the total steel production value due to its specialised applications in critical sectors like automotive, defence, and engineering.

Alloy steel market dynamics:

The Indian alloy steel market demonstrates a dynamic landscape, characterised by both robust domestic production and significant import/export activity. Here's a breakdown:

Domestic production:

Over 45 manufacturers produce alloy steel products across India, highlighting a well-established domestic industry. Specifically, seven-eight manufacturers specialise in alloy steel flat products, catering to diverse industrial needs.

A network of downstream producers further process alloy flat steel, creating value-added products like cold-rolled specialty steel (CRSS).

Import dynamics:

India relies on imports for high-performance flat steel products, such as wear-resistant and high-strength steels, primarily sourced from European countries, indicating a demand for specialised, high-grade materials.

For alloy steel long products, major import sources include China, Japan, and South Korea, signifying strong trade relationships with these Asian steel producers.

Export activity:

India actively exports alloy steel products to various international markets, including Southeast Asia (Thailand), Europe, and the United States, showcasing the competitiveness of Indian alloy steel on a global scale. This shows that the Indian alloy steel market is not only sustaining the domestic needs, but also contributing to the global market.

India's alloy steel capacity and leading producers

India's total alloy steel capacity is approximately 11.5 million tonnes (mnt), as per data maintained by BigMint. The top alloy steel producers with capacity greater than 1 mnt in India are:

• JSW Ispat Special Products Pvt Ltd (Raigarh)
  
  
• Tata Steel Long Products Limited (Gamharia)
  
  
• JSPL (Patratu)
  
  
• Jayaswal Neco Industries Ltd (Raipur)
  
  
• JSW Steel Ltd. (Salem)
  
  
• Sunflag Iron and Steel Co Ltd (Bhandara)
  
  
• Mukand Group
  
  

Alloy steel grade classification:

Alloy steels are created by adding elements like nickel, copper, chromium, or aluminum etc. to regular steel. This blending process significantly enhances the steel's properties, making it stronger and more ductile, as well as improving its resistance to corrosion and making it easier to machine. Common examples of alloy steels include grades like En-8, En-19, 20MnCr5, 42CrMo4, and SAE 4140.

Stainless steels represent a specific category of alloy steels characterised by a high nickel, high chromium content, typically ranging from 10% to 20%. They also often include nickel, silicon, manganese, and carbon in their composition. This unique blend gives stainless steels exceptional resistance to corrosion, making them ideal for outdoor construction and ensuring their longevity even in harsh weather conditions. Stainless steel is widely used in electrical devices. Examples of popular stainless steel grades are SS 200 series, SS 400 series, SS 304 and SS 316.

Die and tool steels are another important classification of alloy steels, specifically designed for use in cutting and drilling tools. These steels typically contain elements like tungsten, molybdenum, cobalt, and vanadium. These additions significantly improve their resistance to heat and overall durability. A key characteristic of tool steels is their ability to maintain their shape even under heavy and prolonged use, making them the preferred material for a wide range of hand tools. Examples of die and tool steel grades include En-31, D2, H13, and H11.

Alloy steel applications:

Alloy steels, with their enhanced properties, find diverse applications across numerous industries. In automotive, they are crucial for engine components, gears, and suspension systems due to their high strength and wear resistance.

Aerospace relies on them for structural parts and jet engine components, where heat resistance and durability are paramount. In construction, alloy steels are used in heavy machinery and structural elements, offering superior load-bearing capacity.

The oil and gas industry employs alloy steels for pipelines and drilling equipment, needing corrosion resistance and high-pressure tolerance.

Tool and die making utilises them for cutting tools and molds, leveraging their hardness and wear resistance. Essentially, any application demanding superior strength, durability, or resistance to extreme conditions benefits from alloy steel's unique characteristics.

Key properties and benefits of alloy steel

The addition of alloying elements significantly alters the characteristics of steel. Notably, alloy steels are prized for:

Increased hardenability: This allows for deeper and more uniform hardening during heat treatment.

Increased corrosion resistance: Certain alloying elements, like chromium, enhance the steel's resistance to rust and other forms of corrosion.

Retention of hardness and strength: Alloy steels maintain their mechanical properties at elevated temperatures, making them suitable for demanding applications.

Enhanced ductility and machinability: Specific alloys improve the ability to be shaped, and machined.

Moreover, alloy steel contributes a substantial 25% to the total steel revenue in the industry, highlighting its economic significance.

Heat treatment processes for alloy steel

Alloy steel properties are meticulously tailored through various heat treatment processes. Spheroidizing yields the softest, most ductile form, while full annealing reduces internal stresses. Process annealing relieves stress in cold-worked steel. Isothermal annealing ensures a uniform microstructure. Normalizing refines the grain for enhanced strength. Quenching provides extreme hardness, albeit with increased brittleness, which can then be tempered to improve toughness. Each method manipulates the steel's microstructure to achieve specific desired mechanical properties.

Manufacturing route of alloy steel in India:

Blast furnace-basic oxygen furnace (BF-BOF) route: This conventional method involves producing steel from iron ore in a blast furnace, followed by refining and alloying in a basic oxygen furnace to achieve the desired alloy steel properties.

Electric arc furnace (EAF) Route: Steel scrap is melted in an electric arc furnace, where alloys are added during the refining stage to produce high-quality alloy steel efficiently.

Induction furnace route: This method uses electromagnetic induction to melt steel scrap and ferroalloys, offering precise control over the alloy composition with minimal energy wastage.

Way Forward

The Indian alloy steel sector holds immense potential, contributing approximately 25% to total steel industry revenue. Despite production currently at 7 million tonnes and a capacity utilisation of 61-70%, the industry has ample opportunity for expansion. By bridging this utilisation gap, advancing high-performance steel production, and fostering innovation, India can enhance its domestic capabilities and strengthen its global presence.