Reliable 40Cr seamless, tough as steel

specification

Product Display

Production process

Hot-rolled (extruded) seamless steel pipe production process:
Round tube billet preparation: Select appropriate 40Cr round steel billet to ensure that its chemical composition, dimensional accuracy, etc. meet the production requirements, and clean the surface of the tube billet to remove impurities such as rust and oil to prevent them from affecting the quality of the steel pipe during subsequent processing.
Heating: Heat the round tube billet to a suitable temperature range, generally around 1000℃-1200℃. The purpose of heating is to make the tube billet have good plasticity, which is convenient for subsequent processing such as perforation and rolling.
Piercing: Use a perforator to perforate a hole in the center of the heated round tube billet to form a rough tube. There are two main methods of perforation: oblique rolling perforation and extrusion perforation. Oblique rolling perforation is through the action of two relatively rotating rollers and a head, so that the tube billet is extruded and perforated while rotating; extrusion perforation is to use an extrusion rod to extrude the tube billet from the extrusion die to form a rough tube.
Three-roller oblique rolling, continuous rolling or extrusion: The perforated rough tube is further rolled or extruded by a three-roller oblique rolling mill, continuous rolling mill or extruder to reduce the wall thickness of the rough tube and increase the diameter to reach the required size specifications. In this process, the internal structure of the steel pipe is further refined and the mechanical properties are improved.
Tube removal: After rolling or extrusion, the steel pipe needs to be separated from the mandrel or mold to form a hollow tube blank. The tube removal method varies according to different production processes. For example, for rough tubes with head perforation, the rough tube is generally removed from the head by a tube removal machine; while steel pipes produced by extrusion process are directly taken out of the mold after extrusion.
Sizing (or diameter reduction): In order to make the outer diameter of the steel pipe more accurate, the tube blank after tube removal needs to be sized or reduced. Sizing is to pass the steel pipe through the sizing machine so that its outer diameter reaches the specified dimensional tolerance range; diameter reduction is to roll the steel pipe on the diameter reducing machine to reduce its outer diameter to the required size, while further improving the dimensional accuracy and surface quality of the steel pipe.
Cooling: The temperature of the steel pipe after sizing or reducing is high, and cooling treatment is required to prevent the steel pipe from generating structural stress and thermal stress when it is naturally cooled in the air, causing deformation or cracking of the steel pipe. The cooling method generally adopts air cooling, water cooling or air cooling, etc., and the appropriate cooling speed is selected according to the material, specification and production requirements of the steel pipe.
Billet pipe straightening: The steel pipe may be bent and deformed after cooling, and it needs to be straightened by a straightening machine to make the straightness of the steel pipe meet the requirements of relevant standards. The main straightening methods include pressure straightening, roller straightening and tension straightening. Select the appropriate straightening method according to the diameter, wall thickness and bending degree of the steel pipe.
Hydrostatic test (or flaw detection): In order to ensure the quality and sealing of the steel pipe, it is necessary to perform hydrostatic test or non-destructive flaw detection on the straightened steel pipe. The water pressure test is to fill the steel pipe with water and apply a certain pressure for a period of time to check whether the steel pipe has defects such as leakage and deformation; non-destructive testing uses ultrasonic testing, eddy current testing or magnetic particle testing to detect cracks, inclusions and other defects inside and on the surface of the steel pipe.
Marking: For steel pipes that have passed the inspection, it is necessary to mark the product specifications, materials, manufacturers, production date and other information on their surfaces for easy identification and traceability. The marking method generally adopts steel stamping, spraying or labeling to ensure that the marking is clear, firm and durable.
Warehousing: After the marking is completed, the 40Cr seamless steel pipe can be stored or delivered for use. When entering the warehouse, it should be classified and stored according to different specifications, materials and quality grades for easy management and search.
Cold drawn (rolled) seamless steel pipe production process:
Round tube billet preparation: Same as the hot rolling process, first select qualified 40Cr round steel billets, and clean and pre-treat the surface to prepare for subsequent processing.
Heating: Heat the round tube to a suitable temperature, usually around 800℃-900℃, so that the tube has good plasticity and machinability.
Perforation: Use a perforator to perforate the heated tube to form a rough tube. The perforation process is similar to the perforation in the hot rolling process, but because the cold-drawn (rolled) steel pipe has higher quality requirements for the rough tube, the process parameters need to be more strictly controlled during the perforation process to ensure the inner surface quality and dimensional accuracy of the rough tube.
Heading: One end of the rough tube after perforation needs to be headed, that is, the end of the rough tube is processed into a shape and size suitable for the cold drawing (rolling) die to facilitate subsequent drawing or rolling operations. The method of heading generally adopts rolling or forging, so that the diameter of the rough tube end is slightly smaller than the diameter of the tube body, and a certain taper is formed.
Annealing: The rough tube after heading needs to be annealed to eliminate the work hardening phenomenon, reduce the hardness and strength of the material, improve its plasticity and toughness, and facilitate subsequent cold processing. The annealing temperature is generally between 600℃-700℃, and the holding time is determined according to factors such as the wall thickness and diameter of the rough tube.
Pickling: A layer of oxide scale will form on the surface of the rough tube after annealing, which needs to be removed by pickling to ensure the surface quality of the steel pipe and the smooth progress of subsequent processing. Pickling generally uses sulfuric acid, hydrochloric acid and other acid solutions for immersion or spraying. After pickling, water washing and neutralization treatment are required to prevent corrosion caused by residual acid on the surface of the steel pipe.
Oiling (copper plating): In order to reduce the friction between the steel pipe and the mold during cold drawing (rolling), improve the service life of the mold and the surface quality of the steel pipe, it is necessary to apply a layer of lubricant, such as engine oil, graphite emulsion, etc., or copper plating on the surface of the rough tube after pickling. The surface of the rough tube after oiling or copper plating is smoother, which is conducive to the smooth drawing or rolling of the steel pipe.
Multi-pass cold drawing (cold rolling): The rough tube after the above treatment can be cold drawn or cold rolled. Cold drawing is to draw the rough tube through the tube drawing die to make the steel tube gradually thinner and elongated; cold rolling is to use a cold rolling mill to roll the rough tube to reduce the wall thickness and outer diameter of the steel tube. In the cold drawing (rolling) process, it is generally necessary to go through multiple processing, and the deformation of each processing should not be too large to prevent defects such as cracks or fractures in the steel tube.
Heat treatment of billet tube: The mechanical properties of the steel tube after cold drawing (rolling) may not meet the use requirements due to the serious work hardening phenomenon, so heat treatment is required. The heat treatment methods generally include quenching and tempering. By adjusting the heat treatment process parameters, the steel tube can obtain the required mechanical properties such as strength, toughness and hardness.
Straightening: Similar to hot-rolled steel tubes, cold-drawn (rolled) steel tubes may also bend and deform, and straightening treatment is required to make the straightness of the steel tube meet the standard requirements. The straightening method of cold-drawn (rolled) steel tubes is basically the same as that of hot-rolled steel tubes, but due to the high hardness of the steel tube after cold processing, a greater straightening force needs to be applied during straightening.
Water pressure test (flaw detection): The cold-drawn (rolled) steel pipe after straightening also needs to be subjected to water pressure test or non-destructive testing to ensure the quality and safety of the steel pipe. The testing methods and requirements are the same as those for hot-rolled steel pipes.
Marking: The cold-drawn (rolled) steel pipes that have passed the inspection are marked in accordance with the specified requirements. The marking content includes the specifications, materials, manufacturers, production date and other information of the steel pipe.
Warehousing: After the marking is completed, the cold-drawn (rolled) 40Cr seamless steel pipe can be stored or shipped.

Why choose us, our advantages

1. Procurement of high-quality raw materials: Our company always insists on purchasing high-quality raw materials from reliable suppliers and strictly controls the quality of raw materials. We have established long-term and stable cooperative relationships with many well-known suppliers of raw materials such as iron ore and coke, ensuring that each batch of raw materials used meets or even exceeds industry standards, laying a solid foundation for the production of high-quality steel.
2. Advanced production technology and equipment: We have a set of advanced production processes and modern production equipment, which enables us to accurately control key indicators such as the chemical composition, mechanical properties and dimensional accuracy of steel. For example, we use advanced steelmaking technology, such as converter steelmaking combined with refining technology, to effectively remove impurities and improve the purity of steel; equipped with high-precision rolling equipment to ensure that the thickness of steel is uniform and the shape is regular, meeting the strict requirements of different customers for steel quality.
3. Strict quality inspection system: We have established a complete and strict quality inspection system, and every link is carefully inspected from the entry of raw materials to the delivery of finished products. We have a professional quality inspection laboratory equipped with advanced testing instruments, such as spectrometers, universal testing machines, ultrasonic flaw detectors, etc., which can comprehensively test the chemical composition, tensile strength, yield strength, elongation, weld quality (if any) and other indicators of steel. Only steel products that have undergone strict testing and are all qualified will flow into the market, ensuring that every piece of steel that customers get is a fine product.
4. Multi-material coverage: Our product line is rich and diverse, covering a variety of common steel materials, including carbon steel, alloy steel, stainless steel, etc. Whether it is ordinary carbon steel needed for building structures, high-strength alloy steel used in machinery manufacturing, automotive industry and other fields, or stainless steel with extremely high corrosion resistance requirements, customers can find suitable products in our company to meet the diverse needs of different industries and different application scenarios.
5. Outstanding cost-effectiveness: Although we have made great efforts in cost control, we have never sacrificed product quality in exchange for low prices. On the contrary, we provide customers with cost-effective steel products based on high-quality product quality and reasonable pricing strategies. When customers buy our steel, they can enjoy high-quality product guarantees and relatively affordable prices, which truly achieves value for money.
6. Professional sales team: We have a professional sales team that not only knows the various performance and characteristics of steel products, but also has rich industry experience and good communication skills. We can accurately understand customer needs, provide customers with professional product consultation and purchase suggestions, and help customers quickly and accurately select the most suitable steel products for themselves.
7. Perfect after-sales service: We are well aware of the importance of after-sales service to customer satisfaction, so we have established a perfect after-sales service system. We provide product quality assurance and return and exchange services. During the quality assurance period, if there are quality problems with the product, we will promptly handle the return and exchange procedures for customers; provide technical support and consulting services, and provide timely and accurate answers to various problems encountered by customers in the process of using steel, such as application guidance, processing technology suggestions, etc.; at the same time, we provide good logistics and delivery services, track logistics transportation and assist customers in delivery acceptance; we also actively collect customer feedback and handle it in a timely manner, and continuously improve service quality.