Cast steel valves are steel used to pour castings. A kind of casting alloy. Cast steel is divided into cast carbon steel, cast low alloy steel, and cast special steel 3 categories. Cast steel is a steel casting produced by the casting method. Cast steel is mainly used in the manufacture of some complex shapes, difficult to forge or cut and shape, but also requires high strength and plasticity of the parts.
Forging steel refers to the use of the forging method and produces a variety of forging materials and forgings. The quality of forged steel parts is higher than cast steel parts, can withstand large impact force, plasticity, toughness, and other mechanical properties are higher than cast steel parts, so where some important machine parts should be used forged steel parts.
Forged steel valves and cast steel valve difference:
The quality of forged steel valves to cast steel valves, which can withstand large impact force, plasticity, toughness, and other aspects of mechanical properties, are higher than cast steel parts. Still, the nominal diameter is relatively small, generally in the DN50 below. The casting of the valve pressure level is relatively low, commonly used nominal pressure of PN16, PN25, PN40, 150LB-900LB. forged steel valve level: PN100, PN160, PN320, 1500LB-3500LB and so on.
Cast steel is mainly used to manufacture complex shapes, difficult to forge, or cutting process forming but also requires high strength and plasticity of the parts.
Casting is liquid forming, and forging is a plastic deformation process. Forging forming a workpiece can improve the internal structure of the organization, good mechanical properties, and grain uniformity, important draught workpiece must be developed, casting will cause organization segregation, and organisational defects, of course, casting has its benefits, forming complex workpiece forging is not easy to open the mold, has been taken to casting.
Introduction to forged valves (forged steel valves):
1, Forging according to the forming method can be divided into:
(1) Closed mode forging (die forging).
Can be divided into die forging, rotary forging, cold heading, extrusion, etc., the metal billet in a forging die with a certain shape of pressure deformation and obtain forgings. The deformation temperature is divided into cold forging (forging temperature is room temperature), warm forging (forging temperature is lower than the recrystallization temperature of the billet metal), and hot forging (forging temperature is higher than the recrystallization temperature).
(2) Open forging (free forging).
1, Manual forging and mechanical forging in two ways, the metal billet on the upper and lower two anvils (against the iron) between the use of impact or pressure to deform the metal billet so as to obtain the required forgings.
2, Forging is one of the two main components of forging, machinery, high load, severe working conditions of the important parts, more forging, and the shape of the simpler available rolled welded parts, except for the profile plate. The forging can eliminate the welded metal material holes and casting state of the loose.
3, The correct choice of forging to improve product quality and reduce costs have a great relationship. Forging materials are mainly carbon steel, stainless steel, and alloy steel. The forging ratio refers to the metal before the deformation of the cross-sectional area and the deformation of the ratio of the mold area. The original state of the material is ingot, bar, liquid metal, and metal powder.
4, The mechanical properties of forgings are generally better than the same material castings, forging is through the forging machinery on the metal billet pressure so that the metal billet plastic deformation in order to obtain a certain shape and size and mechanical properties of the better processing methods.
Casting valves (cast steel valves) details:
1, There are many types of casting, according to the modelling method of ordinary sand casting and special casting:
① Ordinary sand casting, including dry sand, wet sand, and chemical hardening sand 3 categories.
② Special casting, according to the casting material sub-special casting of ore and metal materials, the special casting of two categories;
③ Special casting, according to the casting material sub-special casting of ore and metal materials, special casting.
The special casting of metal as the mould material, including: pressure casting, metal casting, low-pressure casting, continuous casting, centrifugal casting, and so on.
To natural mineral sand and gravel for the casting of special casting materials, including: such as real casting, investment casting, foundry shell casting, mud casting, negative pressure casting, ceramic casting, and so on.
2, Casting is a metal thermal processing technology, casting production has better integrated mechanical properties, casting production of adaptability is broader, and the blank cost is low, for the shape of the more complex, especially with the complex internal structure of the parts, more like casting production of the economy.
3, Casting is the foundation of the modern machinery manufacturing industry, the metal is melted into a liquid and poured into the casting mold, and then after cooling and solidification of the casting will be taken out of the casting after finishing treatment to get a predetermined size and shape and mechanical properties of the casting (billet or parts).
4, Casting process usually includes:
① Preparation of casting molds (so that the liquid metal becomes a solid casting of the molds used, casting molds directly affect the quality of castings), casting molds according to the number of times can be divided into a one-time type, many times the type and the permanent type of casting molds according to the material: metal, sand, mud, ceramic, graphite, etc., ② casting the melting of metal, sand, clay, ceramics, graphite, etc., the casting process is usually included in the casting process, the casting process is usually included in the process.
② Casting metal melting and pouring, casting metal is mainly cast iron, carbon steel, and stainless steel;
③ Casting processing and inspection, casting processing, including the removal of casting surface foreign objects and cores, treatment of protrusions (shovel grinding burrs, excision of pouring risers and treatment of phi seams, etc.), casting heat treatment, shaping, roughing prevention and rust treatment.
5, Casting production mode of disadvantages, casting will produce noise, harmful gases and dust, and other pollution of the environment, and the materials required (such as molding materials, metal, fuel, wood, etc.) and equipment (such as core making machine, metallurgical furnaces, molding machines, sand mixing machines, shot blasting machines, etc.) more.
6, Cast steel is divided into cast carbon steel, cast low alloy steel, and cast special steel 3 categories.
① Cast carbon steel.
Carbon is the main alloying element and contains a small number of other elements of cast steel. Carbon less than 0.2 per cent of the casting of low-carbon steel, carbon 0.2 per cent to 0.5 per cent of the casting of carbon steel, carbon greater than 0.5 per cent of the casting of high-carbon steel. With the increase of carbon content, cast carbon steel strength increases, hardness increases. Cast carbon steel has high strength, plasticity and toughness, low cost, in heavy machinery used in the manufacture of parts to withstand large loads, such as steel mill stand, hydraulic press base, etc.; in railway vehicles used to manufacture the force and impact parts such as rocking pillow, side frame, wheels and hooks.
② Cast low alloy steel.
Containing manganese, chromium, copper and other alloying elements of cast steel. The total amount of alloying elements is generally less than 5%, with greater impact toughness, and can be heat-treated to obtain better mechanical properties. Cast low alloy steel than carbon steel has better performance, can reduce the quality of parts, improve service life.
③ Casting special steel.
Refined to meet the special needs of the alloy cast steel, a wide range of varieties, usually containing one or more of the high amount of alloying elements to obtain a particular performance. For example, containing manganese 11% to 14% of high manganese steel can resist impact wear, more for mining machinery, engineering machinery wear parts; chromium or chromium-nickel as the main alloying element of various stainless steel, used in corrosive or 650 ℃ or more than 650 ℃ high temperature parts, such as chemical valves, pumps, containers, or large-capacity power station turbine shells and so on.
Valve casting process:
1, Casting: that is, the metal is melted into a liquid to meet certain requirements and poured into the casting, after cooling and solidification, cleaning treatment to get a predetermined shape, size and performance of the casting (parts or blanks) of the process. The basic process of modern machinery manufacturing industry.
2, Casting production of blanks at low cost, for complex shapes, especially with complex internal cavity parts, more to show its economy; at the same time it is more adaptable, and has a better overall mechanical properties.
3, But the casting production of materials required (such as metal, wood, fuel, moulding materials, etc.) and equipment (such as metallurgical furnace, sand mixer, moulding machine, core machine, sand machine, shot blasting machine, cast iron plate, etc.) more, and will produce dust, harmful gases and noise and environmental pollution.
4, There are many types of casting, according to the moulding method is customarily divided into:
① Ordinary sand casting, including wet sand, dry sand and chemical hardening sand 3 categories.
② Special casting, according to the modelling material can be divided into natural mineral sand and gravel as the main modelling material for special casting (such as investment casting, mud casting, foundry shell casting, negative pressure casting, solid casting, ceramic casting, etc.) and metal as the main casting material for the special casting (such as metal casting, pressure casting, continuous casting, low-pressure casting, centrifugal casting, etc.) two categories.
5, Casting process usually includes:
① Casting (so that the liquid metal into a solid casting container) preparation, casting according to the material used can be divided into sand, metal, ceramic, mud, graphite, etc., according to the number of times can be divided into a one-time type, semi-permanent and permanent type, casting is ready to prepare for the quality of the casting is the main factor affecting the quality of the casting;
② Casting metal melting and pouring, casting metal (casting alloys) are mainly cast iron, cast steel and cast non-ferrous alloys;
③ Casting processing and inspection, casting processing, including the removal of core and casting surface foreign matter, excision of pouring riser, shovelling burrs and phi seams and other protrusions, as well as heat treatment, shaping, rust treatment and roughing, etc..
Valve forging process:
1, Forging: is the use of forging machinery to exert pressure on the metal billet, so that it produces plastic deformation in order to obtain a certain mechanical properties, certain shapes and sizes of forgings processing methods.
2, One of the two main components of forging. Through the forging can eliminate the casting of metal looseness, welded holes, the mechanical properties of forgings are generally better than the same material castings. Machinery in the high load, severe working conditions of important parts, in addition to the shape of the simpler available rolled sheet, profile or welded parts, more forgings.
3, Forging according to the forming method can be divided into:
① Open forging (free forging). The use of impact or pressure to make the metal in the upper and lower two against the iron (anvil) between the deformation to obtain the required forgings, mainly manual forging and mechanical forging of two kinds.
② Closed mode forging. Metal billet in a certain shape of the forging die chamber pressure deformation and obtain forgings, can be divided into die forging, cold heading, rotary forging, extrusion and so on. According to the deformation temperature forging can be divided into hot forging (processing temperature higher than the recrystallisation temperature of the billet metal), warm forging (lower than the recrystallisation temperature) and cold forging (room temperature).
4, Forging material is mainly a variety of components of carbon steel and alloy steel, followed by aluminium, magnesium, titanium, copper and its alloys. The original state of the material has bar, ingot, metal powder and liquid metal. The ratio of the cross sectional area of the metal before deformation to the mould sectional area after deformation is called forging ratio. The correct choice of forging ratio has a great relationship with improving product quality and reducing cost.
WESDOM Group specializes in pipeline fluid systems: R&D, production and sales of valves, pipe fittings, water meters, flow meters, etc. The products cover cast iron, cast steel, stainless steel, copper, plastics and other materials, which are widely used in hydropower stations, heat, buildings, Water supply and drainage, petroleum, chemical industry, electric power, medical and other fields.
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