Research on Wear-Resistant Steel for Wear Layer of Composite Steel Pipes

Wear-resistant composite steel pipes are widely used in industries such as mining, penjanaan kuasa, Pengeluaran simen, dan metalurgi, di mana pengangkutan bahan kasar menyebabkan haus yang ketara pada saluran paip. These pipes typically consist of an outer steel layer for structural strength and an inner wear-resistant layer designed to withstand abrasion, hakisan, dan kakisan. The wear-resistant layer plays a critical role in extending the service life of the pipe under harsh operating conditions. This research focuses on the study of steel used in the wear layer of composite steel pipes, analyzing material composition, Sifat Mekanikal, and performance parameters.

The primary objective of this study is to identify suitable steel grades for the wear layer, evaluate their performance through key parameters such as hardness, Merupakan, dan memakai rintangan, and present the findings in a structured format. The research also explores the influence of alloying elements and heat treatment processes on the performance of wear-resistant steel. A detailed table of parameters will be provided to summarize the properties of various steel grades, followed by an in-depth analysis of their suitability for wear-resistant applications.

1. Introduction to Wear-Resistant Composite Steel Pipes

Composite steel pipes designed for wear resistance typically consist of two or more layers: an outer structural layer and an inner wear-resistant layer. The outer layer is often made from carbon steel or low-alloy steel to provide mechanical strength and flexibility, while the inner layer, or wear layer, is engineered to resist abrasive wear, hakisan, and sometimes corrosion. Lapisan haus boleh dibuat dari pelbagai bahan, termasuk seramik, Besi Cor-Chromium Tinggi, atau keluli aloi khas. Dalam kajian ini, Tumpuannya adalah pada lapisan haus berasaskan keluli kerana keseimbangan rintangan haus mereka, Merupakan, dan keberkesanan kos.

Lapisan haus mesti menahan keadaan yang melampau, seperti kesan kasar buburan arang batu, bijih mineral, atau klinker simen. Paip keluli karbon tradisional gagal dengan cepat di bawah keadaan sedemikian disebabkan oleh kekerasan terhad dan rintangan haus mereka. Untuk menangani ini, Keluli tahan lasak dengan kekerasan yang tinggi, Ketangguhan yang Baik, dan penentangan terhadap kesan dan keletihan dikembangkan. Keluli ini sering menggabungkan elemen aloi seperti kromium (Cr), Molybdenum (Mo), vanadium (V), dan nikel (Ni) untuk meningkatkan sifat mereka.

Pemilihan keluli tahan haus untuk lapisan dalaman paip komposit melibatkan perdagangan antara kekerasan dan ketangguhan. Kekerasan tinggi meningkatkan ketahanan terhadap lelasan tetapi dapat mengurangkan ketangguhan, Membuat bahan rapuh dan terdedah kepada retak di bawah kesan. Sebaliknya, Ketangguhan yang tinggi meningkatkan ketahanan terhadap kesan tetapi mungkin berkompromi dengan rintangan haus. Kajian ini mengkaji beberapa gred keluli untuk menentukan kesesuaian mereka untuk lapisan haus, memberi tumpuan kepada komposisi kimia mereka, Sifat Mekanikal, dan memakai prestasi.

2. Pemilihan bahan untuk keluli tahan haus

Pilihan keluli untuk lapisan memakai paip komposit bergantung kepada beberapa faktor, termasuk persekitaran operasi, jenis bahan kasar, dan pertimbangan kos. Keluli tahan karat yang biasa digunakan termasuk besi tuang putih-kromium tinggi, keluli martensit, dan keluli bainit. Setiap jenis mempunyai kelebihan dan batasan yang berbeza, yang dibincangkan di bawah.

2.1 Besi tuang putih-kromium tinggi

High-chromium white cast iron is widely used in wear-resistant applications due to its excellent hardness and abrasion resistance. The high chromium content (typically 15–30%) promotes the formation of hard chromium carbides (M7C3 type) in a martensitic matrix, which significantly enhances wear resistance. bagaimanapun, its brittleness limits its use in applications involving high impact.

2.2 keluli martensit

Martensitic steels are heat-treated to achieve a fully martensitic microstructure, which provides high hardness and wear resistance. These steels are often alloyed with elements like chromium, Molybdenum, and vanadium to improve hardenability and wear properties. Martensitic steels offer a better balance of hardness and toughness compared to high-chromium cast iron, making them suitable for applications with moderate impact.

2.3 Bainitic Steel

Bainitic steels are characterized by a bainitic microstructure, which offers a combination of high strength, Merupakan, dan memakai rintangan. These steels are often used in applications requiring resistance to both abrasion and impact. The addition of alloying elements such as boron (b) and molybdenum enhances the formation of bainite during heat treatment.

3. Parameters of Wear-Resistant Steel for Wear Layer

To evaluate the suitability of different steel grades for the wear layer of composite steel pipes, several key parameters are considered, including chemical composition, Kekerasan, Ketangguhan Kesan, and wear rate. These parameters are summarized in the table below.

Notes on Table Parameters:

• komposisi kimia: Peratusan elemen aloi mempengaruhi struktur mikrostruktur dan mekanikal keluli.
• Kekerasan: Diukur dalam kekerasan Rockwell (HRC), Nilai yang lebih tinggi menunjukkan rintangan yang lebih baik untuk lelasan.
• Ketangguhan Kesan: Diukur dalam joules per sentimeter persegi (J/cm²), Nilai yang lebih tinggi menunjukkan rintangan yang lebih baik terhadap kesan.
• Wear Rate: Diukur dalam milimeter padu per Newton-Meter (mm³/N·m), Nilai yang lebih rendah menunjukkan rintangan haus yang lebih baik.
• rawatan haba: Proses yang digunakan untuk mencapai struktur mikro dan sifat yang dikehendaki.

4. Analisis parameter keluli untuk aplikasi lapisan memakai

4.1 Besi Cor-Chromium Tinggi (Keluli a)

Besi Cor-Chromium Tinggi (Keluli a) mempamerkan kekerasan tertinggi di antara bahan yang dinilai, dengan julat HRC 58-62. Ini disebabkan oleh kehadiran karbida keras M7C3 dalam matriks martensit. Kadar haus 1.2 × 10 ⁻⁵ mm³/n · m adalah yang paling rendah, indicating excellent wear resistance. bagaimanapun, its impact toughness is poor (5–10 J/cm²), making it susceptible to cracking under high-impact conditions. This steel is best suited for applications involving pure abrasion, such as transporting fine coal ash or cement slurry, where impact is minimal.

4.2 keluli martensit (Steel B)

keluli martensit (Steel B) offers a balanced combination of hardness (50–55 HRC) and impact toughness (20–30 J/cm²). Its wear rate of 2.5 × 10⁻⁵ mm³/N·m is higher than that of high-chromium cast iron but still acceptable for many applications. The addition of 12% chromium enhances corrosion resistance, while molybdenum and vanadium improve hardenability and wear resistance. This steel is suitable for applications involving moderate impact and abrasion, such as transporting coarse mineral ores.

4.3 Bainitic Steel (Steel C)

Bainitic steel (Steel C) provides the best impact toughness (40–50 J/cm²) among the wear-resistant steels evaluated, with a hardness of 45–50 HRC. Its wear rate of 3.0 × 10⁻⁵ mm³/N·m is higher than that of martensitic steel, indicating slightly lower wear resistance. The bainitic microstructure, achieved through austempering, offers excellent resistance to fatigue and impact. This steel is ideal for applications involving high impact and moderate abrasion, such as pipelines in mining operations with large particle sizes.

4.4 keluli aloi rendah (Steel D)

keluli aloi rendah (Steel D) serves as a baseline for comparison. With a hardness of 40–45 HRC and a wear rate of 5.0 × 10⁻⁵ mm³/N·m, it has the lowest wear resistance among the evaluated materials. bagaimanapun, its impact toughness (60–80 J/cm²) is the highest, menjadikannya sesuai untuk aplikasi di mana rintangan impak adalah kritikal, Tetapi rintangan haus kurang menjadi perhatian. Keluli ini tidak biasanya digunakan untuk lapisan haus tetapi boleh berfungsi sebagai lapisan struktur luar dalam paip komposit.

5. Pengaruh elemen aloi dan rawatan haba

Prestasi keluli tahan haus sangat dipengaruhi oleh komposisi kimia dan proses rawatan haba. Berikut adalah perbincangan terperinci mengenai faktor -faktor ini.

5.1 Peranan Elemen Pengaliran

Elemen Mengalo memainkan peranan penting dalam menentukan mikrostruktur dan sifat keluli tahan haus. Chromium adalah elemen yang paling penting untuk meningkatkan kekerasan dan rintangan memakai dengan membentuk karbida. Dalam besi tuang kritikal tinggi (Keluli a), yang 25% Kandungan kromium menghasilkan pecahan volum tinggi karbida M7C3, contributing to its exceptional wear resistance. Molybdenum improves hardenability and resistance to tempering, while vanadium refines the grain structure and enhances wear resistance by forming fine carbides. In bainitic steel (Steel C), the addition of boron promotes the formation of bainite, improving toughness and fatigue resistance.

5.2 Effect of Heat Treatment

Heat treatment processes such as quenching, Tempering, and austempering are used to achieve the desired microstructure and properties. For martensitic steel (Steel B), quenching followed by tempering produces a fully martensitic microstructure with high hardness and moderate toughness. Austempering, used for bainitic steel (Steel C), involves isothermal transformation to form bainite, which offers a good balance of hardness and toughness. Besi Cor-Chromium Tinggi (Keluli a) is typically used in the as-cast condition with optional tempering to relieve residual stresses.

6. Practical Considerations for Wear Layer Design

When designing the wear layer of composite steel pipes, several practical considerations must be addressed:

• • Operating Environment: The type of abrasive material, particle size, velocity, and impact conditions dictate the choice of steel. For fine abrasives with low impact, high-chromium cast iron is ideal. For coarse materials with high impact, bainitic steel is preferable.

• Cost vs. Prestasi: High-chromium cast iron is more expensive than martensitic or bainitic steel but offers superior wear resistance. The choice depends on the required service life and budget constraints.
• Manufacturability: The wear layer must be metallurgically bonded to the outer steel layer, often through centrifugal casting or cladding. The steel’s compatibility with these processes must be considered.
• Maintenance and Replacement: The wear layer should be designed for easy replacement if necessary. Composite pipes with detachable wear layers can reduce downtime and maintenance costs.

7. Kesimpulan

The wear-resistant layer of composite steel pipes plays a crucial role in extending the service life of pipelines in abrasive environments. This research evaluated four steel grades for their suitability as wear layers: Besi Cor-Chromium Tinggi, keluli martensit, bainitic steel, and low-alloy steel. High-chromium cast iron exhibited the best wear resistance but poor toughness, making it suitable for low-impact applications. Martensitic steel offered a balanced combination of hardness and toughness, while bainitic steel provided the best impact resistance. keluli aloi rendah, while tough, lacked the necessary wear resistance for most applications.

The choice of steel depends on the specific operating conditions, including the type of abrasive material, impact level, and cost constraints. Alloying elements and heat treatment processes significantly influence the performance of wear-resistant steel, allowing for tailored solutions to meet diverse requirements. The parameters presented in the table provide a comprehensive overview of the properties of each steel grade, serving as a valuable reference for engineers and designers.