Características y aplicaciones de las tuberías de acero dulce

What is mild steel pipe?

As the name suggests, low-carbon steel pipes are steel pipes with mild content. Generally speaking, low-carbon steel pipes are different from seamless carbon steel pipes. Low-carbon steel pipes refer to steel pipes with a carbon content of less than 0.3%.Seamless mild steel tube belong to one of them.In addition to general steel pipes, low and medium pressure boiler steel pipes, high pressure boiler steel pipes, alloy steel pipes, stainless steel pipes, petroleum cracking pipes, and other steel pipes, low carbon steel pipes also include carbon thin-walled steel pipes, alloy thin-walled steel pipes, and stainless steel thin-walled steel pipes. , Shaped steel pipe.

Low carbon steel is also called mild steel because of its low strength, low hardness and softness. It includes most ordinary carbon structural steels and some high-quality carbon structural steels, most of which are used for engineering structural parts without heat treatment, and some are used for mechanical parts requiring wear resistance after carburizing and other heat treatments. Low carbon steel with carbon content from 0.10% to 0.30% is easy to accept various such as forging, welding and cutting, and is often used in chains, rivets, bolts, shafts, etc.

20 gauge steel

The 20 of No. 20 steel refers to the carbon content of 0.2%, which belongs to low carbon steel. Steel can be divided into low carbon steel, medium carbon steel and high carbon steel.
Carbon content: low carbon steel is generally less than 0.25%; medium carbon steel is generally between 0.25 and 0.60%; high carbon steel is generally greater than 0.60%.
In addition to the carbon (C) element and a certain amount of silicon (Si) (generally not exceeding 0.40%) and manganese (Mn) (generally not exceeding 0.80%, up to 1.20%) alloying elements for deoxidation, the steel contains Contains no other alloying elements (except residual elements).
Usually, those with a carbon content of less than 0.02% are called wrought iron, those with a carbon content of more than 2.11% to 4.3% are called pig iron, and the ones in the middle are steel.

Characteristic

(1) Characteristics The steel belongs to high-quality low-carbon carbon steel, cold extruded, carburized and hardened steel. The steel has low strength, good toughness, plasticity and weldability. The tensile strength is 253-500MPa, and the elongation is ≥24%.
The characteristics of 20 steel are basically similar to those of 15 steel, but its strength is slightly higher. Uses: Suitable for the manufacture of small and medium-sized carburizing carbonitriding and other parts that are not important in the manufacture of automobiles, tractors and general machinery manufacturing, such as hand brake shoes, lever shafts, gearbox speed forks, transmission passive gears and other parts on automobiles. Camshafts on tractors, suspension equalizer shafts, inner and outer bushings of equalizers, etc.; used to manufacture various mechanical parts that are not stressed but require high toughness under hot rolling or normalizing; in heavy and medium-sized machinery manufacturing Among them, such as forged or pressed tie rods, shackles, levers, sleeves, clamps, etc. In the steam turbine and boiler manufacturing industry, it is mostly used for pipes, flanges, headers and various fasteners working in non-corrosive media with a pressure of ≤6N/square and a temperature of ≤450°C; it is used to make crosses on railways and rolling stock Head, piston and other castings.
Normalizing can promote the spheroidization of the steel, refine the large proeutectoid ferrite, and improve the cutting performance of the blank less than 160HBS.
The process route of the steel mold part is: blanking→forging mold blank→annealing→mechanical rough machining→cold extrusion molding→recrystallization annealing→mechanical finishing→carburizing→quenching, tempering→grinding and polishing→assembly.
(2) Supply status and hardness: Unheated state, hardness ≤ 156HBS.

Chemical composition
(3) Chemical composition of standard JB/T 6057-92 steel (mass fraction, %)

(4) Refer to the corresponding steel number. my country's GB/JB standard steel number is 20, my country's Taiwan CNS standard steel number S20C, German DIN standard material number 1.0402, German DIN standard steel number CK22/C22, British BS standard steel number IC22, France AFNOR standard steel grade CC20, French NF standard steel grade C22, Italian UNI standard steel grade C20/C21, Belgium NBN standard steel grade C25-1, Swedish SS standard steel grade 1450, Spanish UNE standard steel grade F.112, American AISI/ SAE standard steel grade 1020, Japanese JIS standard steel grade S20C/S22C.

Mechanical properties
(5) Phase transition temperature (approximate value) Ac1=735°C, Ac3=855°C, Ar3=835°C, Ar1=680°C
(6) Normalizing specification temperature 920 ~ 950 ℃, air cooling out of the furnace. Hardness 131~156HBS.
(7) Specifications for softening treatment of cold-pressed blanks: Temperature is 700~720°C, holding time is 8~15h, and then at a cooling rate of 50~100°C/h, the temperature is lowered with the furnace to ≤550~600°C, and the furnace is air-cooled.

The hardness before treatment is ≤143HBS, and the hardness after softening is ≤131HBS.
(8) Quenching Specification Temperature 910℃±10℃, 10%NaCl brine cooling.
(9) Measured yield strength fy=245Mpa, elastic modulus E=206Gpa, Poisson's ratio ν=0.3.
(10) The shear strength is 275~392MPa, the tensile strength is 253~500MPa, the yield strength is 275MPa, and the elongation is 25%.
(11) The annealing temperature is only 600-650 degrees, and the holding time is 1-2h.

Allowable stress
The allowable stress of No. 20 steel at 225°C: (16-36mm) between 111-124MPa; (6-16mm) between 117-131MPa
Allowable stress of No. 20 steel at 100°C: 108MPa

Features of mild steel pipe

Mild steel pipe has the characteristics of strong hardness, good toughness, corrosion resistance, high temperature resistance, and superior impact resistance. The surface of low-carbon steel pipe is compact and has many advantages. It can even be galvanized when additional corrosion protection is required.When additional corrosion protection is required, it can even be galvanized, and it has fast forming speed, high output, and does not damage the coating. It can be made into a variety of cross-sectional forms to meet the needs of the use conditions.

Application of mild steel pipe

Mild steel tube is an essential tool in many areas of construction including industrial applications, transport projects and even architectural jobs.

According to the amount of carbon element, iron is usually divided into high carbon steel, medium carbon steel and low carbon steel. The higher the carbon content, the harder the iron, the poorer the toughness, and the easier it is to break. Low-carbon steel is generally rolled into angle steel, channel steel, I-beam, steel pipe, steel strip or steel plate, and is used to make various building components, containers, boxes, furnaces and agricultural machinery. At the same time, low carbon steel pipe.Also an important tool in many fields of construction, including industrial applications, transportation projects and even construction work.

What is the Difference Between High Carbon Steel and Mild steel tube?

1. The difference in toughness: the annealed structure of low carbon steel is ferrite and a small amount of pearlite, its strength and hardness are low, and its plasticity and toughness are good. Therefore, its cold formability is good, and it can be cold formed by curling, bending, stamping and other methods. After proper heat treatment or cold drawing hardening, high carbon steel has high strength and hardness, high elastic limit and fatigue limit, and the cutting performance is acceptable, but the welding performance and cold plastic deformation ability are poor.
2. Application difference: low carbon steel has good weldability. Low carbon steel with carbon content from 0.10% to 0.30% is easy to accept various processing such as forging, welding and cutting, and is often used to manufacture chains, rivets, bolts, shafts, etc. High carbon steel is mainly used to make springs and wear-resistant parts. Carbon tool steel is a high-carbon steel that basically does not add alloying elements. It is also a tool steel with low cost, good cold and hot workability, and a wide range of applications.
3. Different carbon content: low-carbon steel is carbon steel with a carbon content of less than 0.25%, which has low strength and hardness, and good plasticity and toughness; high-carbon steel is often called tool steel, and its carbon content ranges from 0.60% to 1.70%, with high strength and hardness, high elastic limit and fatigue limit, acceptable cutting performance, but poor welding performance and cold plastic deformation ability.