The difference between stainless steel seamless pipe and seamless carbon steel pipe mainly refers to the difference in design rules between stainless steel and carbon steel, which means that the design rules of these two types of steel cannot be used in common. These differences are summarized as follows:
1. Stainless steel undergoes work hardening during cold working, for example, it has anisotropy during bending, that is, the properties of the transverse and longitudinal directions are different. The added strength of cold working can be utilized, but if the bending area is small relative to the total area and this increase is ignored, the added strength can provide some degree of safety factor.
2. The shape of the stress/strain curve is different. The elastic limit of stainless steel is about 50% of the yield stress. As far as the minimum value specified by the standard is concerned, the yield stress value is lower than that of medium carbon steel.
3. Stainless steel has no yield point, usually expressed as 60.2, and the yield stress is considered an equivalent value.
What is seamless carbon steel pipe?
Seamless carbon steel pipes are made of steel ingots or solid tube blanks that are perforated into capillary tubes, and then made by hot rolling, cold rolling or cold drawing. From the perspective of caliber, <φ76 accounts for 35%, and <φ159-650 accounts for 25%. In terms of varieties, general-purpose pipes are 1.9 million tons, accounting for 54%; petroleum pipes are 760,000 tons, accounting for 5.7%; hydraulic props and precision pipes are 150,000 tons, accounting for 4.3%; stainless steel pipes, bearing pipes, and automotive pipes total 50,000 tons tons, accounting for 1.4%.
The raw material for seamless carbon steel pipe is round tube billet, and the round tube billet should be cut by cutting machine to grow billets with a length of about 1 meter, and transported to the furnace by conveyor belt. Billet is fed into the furnace to heat, the temperature is about 1200 degrees Celsius. The fuel is hydrogen or acetylene. Furnace temperature control is a key issue. After the round tube billet is out of the furnace, it must be pierced through a pressure piercer. Generally, the more common piercer is the cone roll piercer. This kind of piercer has high production efficiency, good product quality, large perforation diameter expansion, and can wear a variety of steel types. After piercing, the round tube billet is successively cross-rolled, continuous rolled or extruded by three rolls. After extrusion, the tube should be taken off for sizing. Sizing by high-speed rotary cone drill holes into the billet to form a tube. The inner diameter of the steel pipe is determined by the length of the outer diameter of the drill bit of the sizing machine. After the steel pipe is sized, it enters the cooling tower and is cooled by spraying water. After the steel pipe is cooled, it will be straightened. After straightening, the steel pipe is sent to the metal flaw detector (or hydraulic test) by the conveyor belt for internal flaw detection. If there are cracks, bubbles and other problems inside the steel pipe, they will be detected. After the quality inspection of steel pipes, strict manual selection is required. After the quality inspection of the steel pipe, paint the serial number, specification, production batch number, etc. with paint. And hoisted into the warehouse by crane.
What is stainless steel seamless pipe?
Stainless steel seamless pipe is a steel pipe that is resistant to weak corrosive media such as air, steam, water, and chemically corrosive media such as acid, alkali, and salt. Also known as stainless acid-resistant steel pipe.
The corrosion resistance of stainless steel seamless pipes depends on the alloying elements contained in the steel. Chromium is the basic element for stainless steel to obtain corrosion resistance. When the chromium content in the steel reaches about 12%, the chromium interacts with the oxygen in the corrosive medium to form a thin oxide film (self-passivation film) on the surface of the steel. , can prevent further corrosion of the steel matrix. In addition to chromium, commonly used alloying elements for stainless steel seamless pipes include nickel, molybdenum, titanium, niobium, copper, nitrogen, etc., to meet the requirements for the structure and performance of stainless steel for various purposes.
Stainless steel seamless pipe is a hollow long round steel, widely used in petroleum, chemical, medical, food, light industry, mechanical instrumentation and other industrial pipelines and mechanical structural components. In addition, when the bending and torsional strength are the same, the weight is lighter, so it is also widely used in the manufacture of mechanical parts and engineering structures. It is also commonly used to produce various conventional weapons, barrels, shells, etc.
Production process of stainless steel seamless steel pipe
a. Round steel preparation; b. Heating; c. Hot-rolled perforation; d. cut head; e. pickling; f. Grinding; g. lubrication; h. Cold-rolled processing; i. skim; j. Solution heat treatment; k. straightening; l. pipe cutting; m. pickling; n. Product testing.
The difference between the alloy amount of stainless steel pipe and carbon steel pipe:
Chromium in stainless steel pipes is an alloying element, and the content of chromium alloys is very high, while the main alloying element in carbon steel pipes is carbon, and the content of carbon is the lowest in steel alloys.
The difference between the chemical elements of stainless steel pipe and carbon steel pipe:
Another difference between stainless steel pipe and carbon steel pipe is that the main components of stainless steel pipe are chromium, carbon, phosphorus, manganese, sulfur, nickel and molybdenum in stainless steel pipe while the main components of carbon steel pipe are carbon, manganese, silicon, and copper.
Stainless steel pipes and carbon steel pipes are ferroalloys and belong to the steel class. Steel contains the most carbon by weight. Stainless steel pipes and carbon steel pipes can be distinguished based on alloying elements.
The difference between stainless steel seamless pipe and seamless carbon steel pipe raw materials
Stainless steel
1. There are many types of stainless steel seamless pipes, which refer to alloy steel with a Cr content greater than or equal to 13% and stainless steel in the atmosphere. There are austenitic stainless steel seamless pipes, ferritic stainless steel seamless pipes, martensitic stainless steel seamless pipes, etc. Stainless steel seamless pipes are generally not magnetic, but they are not completely correct. Austenitic is not magnetic, ferritic is, but weaker. Different stainless steel seamless pipes have different corrosion resistance, and the corrosion resistance to different media is also different.
2. In terms of corrosion resistance. In practical applications, stainless steel seamless pipes have excellent properties that cannot be replaced by other steel types. For example, some high temperature resistant stainless steel seamless pipes, the excellent surface properties of stainless steel seamless pipes are widely used for decoration. Material, as well as the excellent mechanical properties of stainless steel seamless pipe, make it used in various manufacturing industries.
Carbon steel
1. Ordinary steel is carbon steel, that is, iron-carbon alloy. According to the carbon content, it can be divided into low carbon steel seamless pipe (referred to as wrought iron), medium carbon steel seamless pipe and cast iron. Generally, those with a carbon content of less than 0.2% are called low-carbon steel seamless pipes (ms seamless pipes), commonly known as wrought iron or pure iron; those with a carbon content of 0.2-1.7% are called steel; those with a content of more than 1.7% are called pig iron .
2. It is usually used on metal parts that require strength, hardness and wear resistance, such as knives, steel cables, piano wires, springs and knives. Machined parts usually require machining and tempering. The higher the carbon content of the steel, the higher its hardness, strength and wear resistance after heat treatment. Carbon steel is divided into high carbon steel, medium carbon steel and low carbon steel; according to their characteristics, high carbon steel is hard and brittle, and low carbon steel is soft and ductile.
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