51CrV4 Spring Steel Strip
51CrV4 is Cloudhammer’s entry level spring steel. It’s perfect for a beginner cutter since it has good resilience and is very durable.
1.8159 (51CrV4) spring steel is a CrV alloy steel which is delivered in the pre-hardened condition. This grade is used for large-section, high load important springs and engineering parts.
Hardening and Tempering
In addition to chromium and vanadium, this grade contains silicon and manganese which all play an important role in improving the steels response to heat treatment. As a result of this it has high hardenability but also high toughness, 51CrV4 spring steel strip making it suitable for use in large-cross-section springs and high load applications.
It can be supplied in the hardened and tempered condition or in the annealed state. The hardening and tempering processes are designed to relieve stresses and achieve more controlled tensile strengths.
When hardened and tempered, the 51CrV4 spring steel strip has good mechanical properties which include tensile strength and elongation at break. The addition of vanadium makes it an excellent alloy for use in parts exposed to stress, shock and vibration.
The microstructure of the as-received commercial 51CrV4 steel bar consists of spheroidite and ferrite grains with spherical carbides distributed dispersed in the ferrite. X-ray diffraction patterns of the as-received and quenched and tempered specimens are shown in Figures 1a and 1b respectively. At the oil-bath temperature of 50 degC, the carbide peaks are small and uniformly distributed, and at 80 degC out-of-oil temperatures, more pronounced dimples are observed in the fracture surface, which indicates a better ductility.
It is important to note that the 51crv4 German spring steel will rust relatively easily, so care should be taken to maintain a thin coating of oil on it. This is particularly important when it is being used for cutting.
Annealing
A good alternative to 5160 is 51crv4, which is what Cloudhammer uses for their smaller knives. This German Spring steel is a great entry level blade material since it can handle much more abuse than the standard T10 clay tempered grades and still retain a good edge. It also holds up to the heat of a hammer, making it easier for the new cutter to get a good edge on softer targets.
This alloy construction steel is often used for springs and other parts that are subject to stress and shock. It is a high quality steel with excellent toughness and can be easily formed. It can be annealed to allow the creation of very complex shapes, while maintaining its strength and toughness.
In the annealed condition, this alloy is very resistant to cracking and brittleness. It can also be forged and machined. Forging is usually done at a temperature between 1050degC and 850degC, with the forged part being slowly cooled down in air.
Bending this type of steel is a little tricky. When bending, it is important to use the largest possible inside radius. If the steel is bent at a lower radius, it will exceed its yield strength and Tinplate steel coils supplier may crack or break. The best way to avoid this is to heat the steel until it is orange-red and then cool it slowly in air.
Heat Treatment
CHROME STEELS containing vanadium (CrV) or molybdenum (CrMo) have even better parameters in comparison with silicon steels, especially in terms of hardness and ductility. They are able to work under significantly higher temperatures, which is why they are used for heavy-duty springs and parts of larger dimensions. This group of grades is also well-known under the designations 58CrV4, 1.8161, and 59CrV4.
The heat treatment of 51CrV4 spring steel strip is one of the main processes that influence its mechanical properties, particularly with regard to its proportional limit and strength, but also its tempering stability and plasticity when cold deformed. It is important that retained austenite does not occur as it can cause dimensional inaccuracies, reduce fatigue strength and adversely affect other material properties.
This is achieved by means of a comprehensive and well-controlled quenching process which is controlled by the oil-bath temperature, the out-of-oil working piece temperature, the cooling rate and the soaking time. By optimising these process conditions the level of spheroidal carbide formation and the distribution of these within the ferrite grains can be optimised, which has a significant positive impact on the microstructure and thus on the mechanical properties of the steel. By doing so, cracks triggered by tensile testing are less likely to propagate along the more brittle grain boundaries and therefore have less detrimental effects on the toughness of the material.
Mechanical Properties
51CrV4 spring steel is a very tough material. It is used for applications that require high toughness, especially in the automobile industry. It can also be used for machine and gear construction, such as camshafts and racks. This material is characterized by its great hardenability, good hot working performance and comprehensive mechanical properties.
This work investigated the effects of quenching conditions on the microstructure and mechanical properties of 51CrV4. The morphological examination focused on the as-quenched martensite and tempered troostite. The tensile and hardness tests showed that the tempered microstructure improved with increasing oil-bath temperature. The tempered microstructure displayed more spherical carbide particles and smaller intercarbide spacings, which resulted in better ductility.
In addition, the soaking time and tempering temperature were optimized for the best possible mechanical properties. The resulting steel was used to fabricate coil springs for train bogies. These bogies are required to carry heavy loads and impose stringent requirements on the mechanical properties of the springs.
The soaked and tempered 51CrV4 steel has excellent resistance to fatigue and can withstand heavy loads. It can be butt welded by argon arc welding to form quality welds. The welds show obvious brittle fracture morphology at the fusion line and in the heat-affected zone. This characteristic improves the reliability of bogies for transporting very heavy and long goods.
