THREE-PHASE STEEL PRODUCT WITH HIGH FORMABILITY PROPERTIES AND THE HEAT TREATMENT METHOD FOR OBTAINING THIS PRODUCT.

Abstract

The invention relates to a steel product that provides high strength values ​​while also exhibiting formability, for use in the automotive and similar industrial sectors, and a method for its production.

Description

1 TARIFF THREE-PHASE STEEL PRODUCT WITH HIGH FORMABILITY. AND THE HEAT TREATMENT METHOD USED TO OBTAIN THIS PRODUCT. TECHNICAL FIELD The invention is designed for use in the automotive and similar industrial sectors, for high strength. a steel product that provides its values ​​and also offers formability. It relates to a method for its production. 10 PREVIOUS TECHNIQUE As is known in the technical field, advanced high-strength materials are used in the automotive industry. Advanced High Strength Steels (AHSS) offer high strength and formability. It is among the steel grades developed to ensure stability. This One of the most commonly used types of steel is a combination of ferrite and martensite phases. These are dual-phase (DP) steels. Dual-phase steels are a class of low-carbon steels that have a soft microstructure. Advanced high-strength material containing both ferrite and hard martensite phases. These are steels. Thanks to this structure, the ferrite phase gives the steel high ductility and formability. While the martensite phase provides strength and yield strength, it generally offers high strength and yield limit. These steels, containing 10–30% martensite by volume, offer strength and They offer a balanced performance between formability and performance, especially in the automotive industry. 25 It is preferred in the production of load-bearing and energy-absorbing parts in the industry. In the relevant technical field, dual-phase steels used in the automotive industry have complex geometries. insufficient deformation capability of the parts during shaping Therefore, tearing and cracking problems are encountered. Existing dual-phase steels, 30 It fails to offer sufficient formability while maintaining high strength; furthermore Current heat treatment methods cannot precisely control phase transformations, and Because it cannot be fully integrated into industrial production lines, it affects production efficiency and product quality. It has negative effects on them. 2 In order to achieve high formability, certain heat treatments are applied in the relevant technical field. Methods have been developed. These methods generally involve processing steel within specific temperature ranges. The aim is to anneal and cool the material in a controlled manner; thus, the grain structure and phase The aim is to improve the phase distribution. However, current processes cannot achieve the desired phase balance. It cannot create sensitivity. 5 The methods applied in the technique have been only partially successful in increasing the level of malleability. However, process inconsistencies encountered during implementation, microstructural control due to challenges and lack of industrial integration, expected performance It is unable to provide this. In this context, both increasing the level of malleability and 10 Alternative microstructures that can be produced to be compatible with industrial heat treatment lines. Production methods are needed. The subject of the invention, published under number CN114875222 A, is a high-strength and low-yield material. The method of preparing martensitic ferrite biphasic steel with a strength ratio of 15 It is related. The subject of the invention, publication number US11186890 B, consists of martensite and residual austenite phases. This relates to a two-phase steel and its production method. Steel sheets are produced at a temperature of 620-660°C. It is tempered for 10-300 minutes and then rapidly cooled to room temperature by adding water. It is cooled. The resulting sheets have a thickness of 10-30% at room temperature. It is subjected to cold rolling with a discount. In the final stage, the aforementioned sheets are 300- It undergoes a second annealing process at 700°C for 3-60 minutes and is then quenched in water again. It is then cooled to room temperature; thus, the martensite and residual austenite phases are separated. The desired two-phase steel microstructure is obtained. 25 In conclusion, all the problems mentioned above are adaptable within the relevant technical field. high-performance, microstructure-controlled, and industrially applicable multiphase steels This has made it necessary to improve the methods used for its production. A BRIEF DESCRIPTION OF THE INVENTION As is known in technology, the formability properties of high-strength steels Existing heat treatment methods applied with the aim of increasing phase transformations 3 challenges in control as well as limitations in integration into industrial production lines It cannot deliver the desired level of performance due to this, especially ferrite and martensite. In dual-phase steels containing different phases, during complex forming operations problems such as tearing and cracking due to insufficient deformation capacity This situation can be encountered. This negatively affects production efficiency and product quality. 5 It has an effect. To remedy these shortcomings, the existing inventors have developed a system with a specific chemical composition. a three-phase steel material containing ferrite, martensite and residual austenite phases together It presents a method for processing in a way that will create a microstructure. (Page 10) Thanks to this method, improved formability is achieved along with high strength. performance is ensured and tearing and cracking that may occur during shaping. Steel compositions with reduced risks can be obtained. The aim of this invention is to combine high strength with high formability properties. 15 obtaining a three-phase steel that can offer and contains ferrite, martensite and residual austenite phases together. The goal is to propose a method for achieving this. The aim of this invention is to overcome the challenges encountered during the production of parts with complex geometries. Three-phase steel micro 20 that contributes to reducing tearing and cracking problems. The aim is to present a method for obtaining its structure. The aim of this invention is to obtain three-phase steel with a residual austenite phase in its microstructure. by enabling it to be shaped, increasing its deformation capability during forming processes, and A method that offers a balanced performance between strength and formability has emerged. 25 to place. The aim of this invention is to create a controlled environment in which ferrite, martensite, and residual austenite phases coexist. by enabling the creation of a microstructure, ensuring structural integrity, service life, and A three-phase steel production method that contributes to improving safety in use. 30 to reveal. 4 Another objective of the invention is to enable the appropriate heat treatment of steel material with a specific chemical composition. By processing under these conditions, an industrially viable three-phase steel can be obtained. The goal is to present the method. DETAILED DESCRIPTION OF THE INVENTION 5 In this detailed description, the subject of the invention is high strength and formability. performance improved three-phase steel and the application for obtaining these three-phase steels. These explanations relate to the method and are intended solely to facilitate a better understanding of the subject. It includes and is in no way restrictive. 10 The steel grade discussed in this invention is referred to as three-phase steel. Three-phase steel, having ferrite, martensite and residual austenite phases together in its microstructure and this This type of steel exhibits mechanical properties resulting from the interaction of phases. In steels, high strength and high 15 are achieved thanks to the balanced combination of different phases. Properties such as formability can be achieved together. Three-phase steels, primarily by optimizing the chemical composition it contains, followed by controlled application accordingly. It can be obtained through heat treatments. In current technology, dual-phase steels containing ferrite and martensite phases offer high strength at 20°C. It strikes a certain balance between formability and complexity. However, it is complex. insufficient deformation capability during the shaping of parts with geometries Due to its presence, problems such as tearing and cracking may occur. The existing The invention aims to reduce these problems by incorporating ferrite and martensite phases. It is also related to the production of three-phase steel, which includes the residual austenite phase. 25 In the present invention, the goal is to enable three-phase steel to possess the targeted technical characteristics and undergo thermal processing. First, chemical composition optimization is necessary to ensure suitability for the processes. This is being carried out. Accordingly, the steel composition to be used in the production of three-phase steel The values ​​of carbon, manganese, and silicon components are determined in a balanced manner. 30 Accordingly, the carbon present in three-phase steel supports the formation of the hard phase. It increases the tensile strength of the material and promotes martensite formation. The three-phase steel that is the subject of the present invention contains between 0.13% and 0.18% by weight. It contains a certain amount of carbon. For the production of three-phase steel, the manganese content must be at least 2% by weight. Manganese, Since it is an element that increases the stability of the austenite phase, a certain amount of 5 after cooling. It plays a role in preserving residual austenite in the microstructure. The determined ratio Thanks to this, the austenite phase becomes enriched with carbon and is completely removed during cooling. It remains stable in the structure without transforming into martensite. Thus, it offers high strength. and high formability properties are offered together, as well as deformation. During this process, homogeneous flow is ensured, reducing the risk of tearing and cracking. The 10 mentioned above... Manganese content is necessary for the three-phase steel structure to deliver the desired mechanical performance. It allows for the creation of a balanced chemical composition. The three-phase steel discussed in the invention is designed to control phase transformations and austenite. To limit its stabilization, a value between 0.18% and 0.22% by weight is used. It contains silicon. The specified weight ratios are particularly suitable for heat-treated three-phase steels. during which the targeted phase balance is achieved and moldability is increased It contributes. In order for steel characterized in this way to have three-phase steel quality, the invention requires 20 The subject matter involves the application of the method and process steps. Within the scope of the present invention... The developed production method specifically combines ferrite, martensite, and residual austenite phases. This enables the creation of a three-phase microstructure containing three phases; this results in both mechanical and mechanical properties of the steel. It optimizes both its strength and formability properties. The process steps for obtaining three-phase steel, as characterized, are listed in the following lines: It is being shared. - First Heating Process The steel characterized in the invention has a first value between the transformation temperatures of A1 and A3. It is subjected to a heating process. 6 In this invention, steel is most often used at temperatures ranging from 680 to 720 °C. It is subjected to a heating process at a specific temperature. This temperature value affects the microstructure of the steel. It is the temperature at which ferrite and austenite phases coexist in a stable manner. Optimized in the invention. In steel containing manganese and carbon as it is manufactured, the phases between carbon and manganese are... Diffusion of the elements is possible. The temperature value is 5 to the A1 transformation temperature. Since it is a close value, the austenite phase also chemically develops while maintaining the dominance of the ferrite phase. This allows it to become richer and more stable. Thus, cooling down. After the process, an intermediate microstructure is created that will offer the desired mechanical properties, achieving both high strength and high formability properties It is becoming possible. 10 To achieve the aforementioned technical solutions and advantages, the annealing time ranges from 8 to 40 hours. It is a certain value. This period represents the balanced formation of ferrite and austenite phases within the steel material. This is due to the diffusion of carbon and manganese elements between the phases in question. through which it redistributes and the austenite phase becomes chemically stable. 15 It allows for phase transformations and elemental distribution in periods shorter than 8 hours. While this may not be achieved to a sufficient degree, annealing processes exceeding 40 hours lead to unnecessary energy consumption. and can lead to grain coarsening. Therefore, the 8–40 hour interval is ideal for the intermediate microstructure. It represents suitable values ​​in terms of homogeneity and economic efficiency. - Cooling and Partial Austenitization Formation After the first heating step, the steel undergoes a controlled cooling process. This process is carried out by incorporating the ferrite phase into the microstructure of the resulting steel. Together, a residual austenite phase with high manganese content is formed. This microstructure, 25 An intermediate structure that is advantageous in terms of the deformation capability of the material before shaping. It consists of carbon (C) and manganese (Mn), especially in the first heating process step. elements diffusion between ferrite and austenite phases that are simultaneously present in the microstructure. They are redistributed through this process. In this process, the elements C and Mn are more concentrated in the austenite phase. by dissolving in this way, it makes this phase chemically more stable, forming an intermediate microstructure. 30 It is possible to obtain steel with this property. Controlled cooling is critical in this step, because cooling its speed should not be too slow, but it will complete the phase transformations in the undesirable direction. 7 It is not that fast. Thus, a balanced ferrite-austenite distribution in the microstructure. is being created and will provide more homogeneous deformation during shaping processes. An intermediate structure is obtained. Accordingly, controlled cooling process in HNx atmosphere. The processes are carried out at a temperature between 0.6 and 1.5 °C / min. This is ensured. 5 Controlled cooling is critical in this step, because cooling its speed should not be too slow, but it will complete the phase transformations in the undesirable direction. It shouldn't be that fast either. This way, a balanced ferrite-austenite structure can be achieved in the microstructure. distribution is created and more homogeneous deformation is achieved during shaping processes. 10 An intermediate structure is obtained that will provide this. Accordingly, the controlled cooling process HNx The processes are carried out in the atmosphere and at a temperature between 0.6 and 1.5 °C / min. This is ensured. - Second Heating Process 15 The most critical process step for obtaining three-phase steel is the second heating process. This second heating The process is carried out at a temperature between A1 and A3. Accordingly, the second heating process for obtaining three-phase steel is at a temperature between 700 and 800 °C. This is achieved within this temperature range, allowing for the controlled stabilization of the austenite phase. by facilitating the formation of a balanced microstructure between ferrite, martensite, and the third phase. This ensures its formation. Austenite transformation is insufficient at temperatures below 700 °C. ...remains, but at temperatures above 800 °C, grain coarsening and undesirable phases occur. Segregation can occur. Therefore, the 700–800 °C range is suitable for three-phase steel. suitable temperature that optimizes high strength and formability properties It is the range. This second heating process takes between 10 and 120 seconds. The stated time only covers the waiting time above A3 temperature and the heating 30 The duration is not included in this range. Austenite transformation is insufficient in durations shorter than 10 seconds. remaining there, and in times exceeding 120 seconds, microscopic grain coarsening and undesirable phase formation occur. Separations can occur. Therefore, the 10–120 second interval is suitable for three-phase steel. It provides optimum conditions for achieving the targeted microstructure. 8 After the second heating process is carried out at the specified temperature values, the intermediate micro The issue is the rapid cooling process of steels with this structure. These two The final microstructure obtained as a result of the staged controlled heat treatment process is ferrite and martensite. It consists of residual austenite phases. Thanks to this structure, the steel has high tensile strength. It gains strength and superior formability properties. Thus, the collision energy is reduced to 5. High performance in automotive safety-critical functions such as absorption. This shows that the residual austenite phase undergoes plastic deformation during forming. It provides. The three-phase steel obtained by applying the aforementioned process steps contains 10 by volume. It contains 10% to 20% martensite and 0.75% to 2% residual austenite. This volumetric distribution provides an optimal balance between high strength and formability. This ensures that the desired strength is not achieved if the martensite content falls below 10%. While it cannot be shaped, if it exceeds 20%, the shaping effect will be negative. is affected. Similarly, if the residual austenite content remains below 0.75%, 15 It reduces the effect of convertible austenite, and exceeding 2% affects the microstructure. This leads to stability problems. Therefore, these ranges are suitable for three-phase steel. This is critical for achieving high performance in automotive and similar applications. The processes applied during the production of three-phase steel alter the martensite microstructure, resulting in product 20. It is obtained in a value ranging from 10% to 20% by volume. As stated. Three-phase steel production provides high strength along with superior formability properties. is obtained. The residual austenite phase, which is stable in the microstructure, is shaped. transforming into martensite due to the plastic deformation effect applied during the processes It increases the elongation capacity of the material and reduces the risk of cracking. Also 25 The balanced presence of hard and soft phases in the microstructure allows for a more homogeneous distribution of stress. By causing it to disintegrate, it improves both strength and ductility performance. The resulting steel material is used in the production of parts with complex geometries. It offers high formability, impact resistance and energy absorption capacity. It also demonstrates superior performance in this regard. 30 The high energy absorption capacity offered by the microstructure developed within the scope of the invention, Used especially in safety components requiring impact resistance in the automotive sector. It presents an ideal structure for this. In addition, production is facilitated by controlled phase transformations. 9 This ensures consistency in mechanical properties, thus extending the service life of the products. User safety is being improved. The scope of protection of the invention is specified in the claims attached hereto, and these details are strictly adhered to. The explanation cannot be limited to those given for illustrative purposes. Because a technically expert 5 the person, without deviating from the main theme of the invention, in light of what has been described above, similar It is clear that these structures can emerge.

Claims

REQUESTS 1. The invention is a method for obtaining a three-phase steel, characterized by the following process: It includes the following steps: - contains between 0.13% and 0.18% carbon by weight, and at least 2% manganese. and a steel composition containing silicon in the range of 0.18% to 0.22% ensuring, - between the A1 and A3 transformation temperatures of the steel material, which is between 680 and 720 subjected to a first heating process at a temperature in the °C range and an intermediate Production of steel with microstructure, 10 - steel material subjected to the first heating process at 0.6 to 1.5 °C / min subjected to a cooling process within this range, - steel subjected to cooling treatment, within the transformation temperature range of A1 to A3, and A second heating process is applied at a temperature between 700 and 800 °C. - cooling is achieved by rapid cooling after the second heating process, resulting in 15 minutes of cooling. its production and the presence of ferrite, residual austenite and martensite phases within it. A three-phase steel production process involving...

2. A method that conforms to Claim 1, characterized by its process of ensuring the steel composition. The manganese content at this step should be between 2% and 3%. 20 3. A method that conforms to claim 1 or 2, characterized by the duration of the first heating process being 8 hours. It should be within a range of 40 hours.

4. A method suitable for any of the previous requests, characterized by; second heating 25 After processing, the percentage by volume is between 10% and 20% martensite, and between 0.75% and 2%. A three-phase steel is obtained containing residual austenite and ferrite in the remaining part. It is the fact that.

5. Obtained by a method suitable for any of the previous requests, with a microstructure of 30 It is a three-phase steel containing ferrite, martensite, and residual austenite phases together, feature; It contains 0.13% to 0.18% carbon by weight. 2 to 3% manganese by weight, It contains 0.18% to 0.22% silicon by weight and 35 11 Martensite ranging from 10% to 20% by volume, residual austenite ranging from 0.75% to 2%. and the remaining part contains the ferrite phase.