C45/1045/1.1191/S45C Carbon Steel

1045/C45 steel is defined as medium carbon steel which has 0.4%-0.5% Carbon.It offers good weldability, good machinability, high strength and impact properties,but low in hardenability because of lack of suitable alloying elements,but it can obtain surface hardnesses 54-60HRC after flame or induction hardening. 1045/C45 steel is generally supplied in the black hot forged or normalized condition,and has a tensile strength of 570 -700 MPa with surface hardness170-210HB.

Chemical Composition(%)

Application

1045 Round bar is used in a variety of industry sectors for applications requiring more strength than low carbon mild steels. Some typical applications for 1045 round bar are axles, bolts, connecting rods, studs, rams, pins, rolls, spindles, ratchets, crankshafts, torsion bars, sockets, worms, light gears, guide rods etc.

Mechanical Property

Heat Treatment Conditions

# An In-Depth Look at 1.1191 Steel – Properties, Applications, and More

Steel alloys designated 1.1191 refer to a family of chromium-molybdenum steels that possess excellent mechanical properties and corrosion resistance. With controlled additions of alloying elements like chromium, molybdenum, and vanadium, 1.1191 steels exhibit high strength, hardness, and creep resistance even at elevated temperatures. This makes them suitable for a wide range of demanding applications in industries like power generation, chemical processing, and transportation.

## Overview of 1.1191 Steel

The 1.1191 designation indicates a chromium-molybdenum steel alloyed with vanadium. Typical compositions contain 0.08-0.15% carbon, 0.3-0.6% manganese, 0.25-0.45% silicon, 10.5-12.5% chromium, 0.8-1.2% molybdenum, and 0.15-0.25% vanadium. Small amounts of other elements like nickel, niobium, and nitrogen may also be present.

Key characteristics of 1.1191 steel include:

– High strength and creep resistance at elevated temperatures up to approximately 540°C
– Excellent corrosion and oxidation resistance
– Good fabricability and weldability compared to other high-alloy steels
– Attractive combination of properties relative to cost

The microstructure of 1.1191 steel consists of tempered martensite and fine vanadium-rich carbide precipitates. The chromium provides oxidation resistance while molybdenum and vanadium contribute to high-temperature strength through solid solution and precipitation strengthening mechanisms.

1.1191 steels are produced using specialized melting, casting, hot working, heat treatment, and thermomechanical processing to develop the desired microstructure and properties. They can be supplied in various product forms including plate, pipe, forgings, and bar.

## Mechanical Properties

The mechanical properties of 1.1191 steel can vary depending on exact composition and processing. However, typical properties include:

– Tensile strength: 650-850 MPa
– Yield strength: 450-650 MPa
– Elongation: 16-22%
– Reduction of area: 30-45%
– Hardness: 190-230 HB

The material retains good ductility along with high strength. 1.1191 steel is significantly stronger than common carbon and low-alloy steels while having better fabricability than more highly alloyed grades.

The properties of 1.1191 are maintained up to approximately 500-550°C. At higher temperatures, creep resistance becomes the limiting factor. With proper heat treatment and processing, 1.1191 can provide rupture strength over 100 MPa for 100,000 hours at 540°C. This allows the material to withstand very demanding high-temperature applications.

## Corrosion Resistance

A critical advantage of 1.1191 steel is its corrosion and oxidation resistance stemming from the chromium content. In most environments, the material forms a protective chromium-rich oxide surface film that resists corrosion.

1.1191 exhibits excellent resistance to high-temperature oxidation and carburization. It also withstands corrosive atmospheres containing carbon dioxide, sulfur compounds, and hydrogen sulfide. This makes it well-suited for equipment exposed to hot gases, combustion products, and chemical fumes.

For increased corrosion resistance, 1.1191 steel can be produced with slightly higher chromium levels up to 13%. The material has good resistance to chloride-induced stress corrosion cracking, which can be an issue with some stainless steels. Overall, 1.1191 provides a valuable combination of mechanical strength and environmental durability.

## Applications of 1.1191 Steel

The unique properties of 1.1191 steel make it suitable for demanding applications in multiple industries:

**Power Generation**

– Boiler parts
– Steam pipes and tubing
– Heat exchangers
– Valves, fittings, and fasteners

**Chemical Processing**

– Reformer tubes
– Cracking furnaces
– Heat exchangers
– Process piping and vessels

**Transportation**

– Turbine and exhaust components
– Engine valves and fasteners
– Piping and tubing systems

**Oil and Gas Production**

– Downhole tubing
– Wellhead equipment
– Transmission pipelines

In these challenging environments, 1.1191 provides the required mechanical performance at high temperatures along with resistance to corrosion, oxidation, and carburization. It offers a cost-effective solution relative to more expensive nickel-based alloys.

## Working with 1.1191 Steel

Despite its high strength, 1.1191 steel can be readily fabricated and machined using conventional methods. It has good cold formability and responds well to bending, drawing, heading, and other forming operations. The material also has excellent weldability compared to other chromium-molybdenum alloys.

Preheating may be required for welding or other joining processes depending on section thickness and service requirements. Post-weld heat treatment can help relieve stresses and restore optimal properties. Standard machining techniques work well for 1.1191 but high-speed steel tooling is recommended due to the material’s strength and work hardening characteristics.

With proper precautions, 1.1191 steel provides a very useful engineering material that can be fabricated, joined, and machined using typical workshop methods. Its combination of fabrication flexibility and performance in demanding environments makes it a valuable alloy.

## 1.1191 vs. Other Alloys

1.1191 steel occupies a middle ground between lower alloy ferritic steels and more highly alloyed austenitic grades:

– Compared to low alloy Cr-Mo steels like P22, 1.1191 offers higher temperature capability and corrosion resistance due to increased alloy content.

– Relative to 300 series stainless steels, 1.1191 has higher strength at elevated temperatures along with better creep resistance and thermal fatigue properties.

– Versus nickel-based superalloys, 1.1191 provides good high-temperature properties at much lower cost while being easier to fabricate and weld.

In many situations, 1.1191 hits a sweet spot between performance, ease of fabrication, and cost-effectiveness. Its capabilities align well with applications that operate in the 500-600°C range where strength and corrosion resistance are critical.

## Availability of 1.1191 Steel

1.1191 steel is readily available from major producers in standard plate, pipe, bar, and forgings. It may also be sourced as custom castings or fasteners to meet application-specific property requirements. Some inventory is normally held by distributors and service centers for rapid delivery.

Being a widely used alloy, 1.1191 benefits from well-established manufacturing and supply infrastructure. Lead times are reasonable, especially for common product forms and sizes. End users can easily source this material for prototyping needs through full-scale production demands.

While not the most exotic or highly engineered alloy, 1.1191 steel provides an optimal combination of fabrication characteristics, mechanical properties, and corrosion resistance for critical high-temperature applications. With capabilities that bridge the gap between stainless steels and superalloys, it serves an important role across multiple industries. For designers, engineers, and procurement specialists dealing with demanding equipment environments, 1.1191 is a versatile material choice worth considering.