Preface

In the vast field of materials science, stainless steel has become an indispensable part of modern industry and fashion design due to its unique properties and style. From the industrial revolution of the early 20th century to contemporary fashion trends, stainless steel has not only witnessed technological advancements but has also become a significant symbol of human civilization's development. This series of articles will delve into the evolution of stainless steel, its application and development in watchmaking, and its historical evolution as a fashion element.

Part One: "The History and Evolution of Stainless Steel as a Metal Material"

This article will trace the origins of stainless steel, exploring how it evolved from an experimental alloy into a critical material in modern industry. We will review the early development of stainless steel, analyze how technological breakthroughs have propelled its widespread application across various industrial sectors, and discuss its classification and characteristics.

Part Two: "The Application and Development of Stainless Steel in Watchmaking"

In watchmaking, the application of stainless steel is particularly prominent. This article will delve into the importance of stainless steel in watch manufacturing, including how its properties meet the requirements of precision manufacturing, and how technological innovations drive the diversification and high performance of stainless steel watches. Additionally, this article will analyze consumer acceptance and preferences for stainless steel watches, as well as the opportunities and challenges facing stainless steel watches in the future.

Part Three: "From Utility to Fashion: The Historical Evolution of Stainless Steel Watches"

Stainless steel watches are not just utilitarian items but also symbols of fashion. This article will explore how stainless steel watches have evolved from simple functional products to fashion accessories, analyzing how the fusion of design and engineering has shaped the classic image of stainless steel watches and examining their role in different cultures and markets. Moreover, the article will evaluate how technological advancements and design innovations collectively drive the continuous development of the stainless steel watch industry.

The History and Evolution of Stainless Steel as a Metal Material

This article will trace the origins of stainless steel, exploring how it evolved from an experimental alloy into a crucial material in modern industry. We will review the early development of stainless steel, analyze how technological breakthroughs have driven its widespread application across various industrial sectors, and discuss the classifications, properties, environmental impact, and sustainable development strategies of stainless steel. Finally, we will look ahead to the potential applications of stainless steel in new technologies and its future development trends.

Introduction

In the progression of human civilization, the development of materials science has always played a crucial role. Stainless steel, an alloy with exceptional corrosion resistance and remarkable strength, has revolutionized our world since its discovery in the early 20th century. From industrial production to everyday life, the applications of stainless steel are ubiquitous. Its development history represents not only a leap in materials science but also a reflection of modern industrial advancement.

Early Development

1. Iron, Steel, and Stainless Steel

Iron (chemical symbol: Fe), originating from the Latin word "Ferrum", is a chemical element with an atomic number of 26 and an atomic weight of 55.845 u. It belongs to the first series of transition elements, situated in Group 8 of the periodic table. Iron is the most abundant element by mass in the Earth's crust and constitutes a significant portion of both the Earth's outer and inner core. It is the fourth most abundant element in the Earth's crust. iron ore

Pure iron is rare in the Earth's crust and is mainly found in meteorites. While iron ore deposits are abundant, extracting usable iron metal requires temperatures exceeding 1500°C, which is 500°C higher than the temperature required for smelting copper. The smelting of iron began around 2000 BCE in Eurasia, gradually replacing copper alloys in some regions by around 1200 BCE, marking the transition from the Bronze Age to the Iron Age. Due to its mechanical properties and low cost, iron alloys such as steel, stainless steel, and alloy steel remain the most common industrial metals to date.

Pure iron surfaces exhibit a silver-grey color akin to a mirror, but iron readily reacts with oxygen and water to form brown or black-hydrated iron oxide, commonly known as rust. Unlike the oxides of other metals that may passivate the metal, rust has a greater volume than the original iron, causing it to flake off, exposing new surfaces to further corrosion. Despite its reactivity, electrolytically produced high-purity iron exhibits good corrosion resistance.

Steel, also known as steel iron, is an alloy composed of iron and other elements, most commonly carbon, and is currently one of the most widely used metal materials. Carbon content typically ranges from 0.02% to 2.0% of the weight of steel, depending on the grade. Other alloying elements may include manganese, chromium, vanadium, and tungsten.

Adding nickel and manganese increases the strength of steel and stabilizes its austenitic properties, while the addition of chromium increases hardness and melting point. The addition of vanadium also increases hardness while reducing the effects of metal fatigue. To prevent corrosion, a minimum of 11% chromium is required, which forms a hard oxide layer on the surface; this alloy is called stainless steel. cold weapon

Stainless steel is a type of steel known for its corrosion resistance properties. It typically contains chromium and other alloying elements. The addition of chromium forms a dense oxide film, which prevents further oxidation and corrosion of the steel surface. Stainless steel exhibits excellent corrosion resistance, aesthetic appeal, and durability, making it widely used in various fields.

2. The Long Road from Steel to Stainless Steel

The earliest known steel artifacts date back to approximately four thousand years ago, with one such artifact unearthed at the Kaman-Kalehoyuk site in Anatolia, Turkey. Other ancient steel artifacts have been found in East Africa, dating back to around 1400 BCE. Knight and sword

In the 4th century BCE, steel weapons resembling the Iberian falcata were produced in the Iberian Peninsula, while the Roman military used steel weapons produced in Noricum.

During the Warring States period (403–221 BCE), China employed quenching to harden steel, and by the Han Dynasty (202 BCE – 220 CE), steel was produced by smelting wrought iron and cast iron together. This technique resulted in the production of medium carbon steel in the 1st century CE.

Nearly 2,000 years ago, the Haya people of East Africa invented a high-temperature furnace, allowing them to forge carbon steel at temperatures as high as 1,802°C.

The study of producing corrosion-resistant steel can be traced back to the early 19th century. Early experiments primarily focused on improving the chemical composition and processing techniques of steel to enhance its corrosion resistance.

In the late 19th century, British researcher Harry Brearley and others began systematic research on alloy steel, aiming to develop a sort of steel that was resistant to rust. In 1913, Brearley successfully produced one type of steel containing 13% chromium, which was called "stainless steel." This discovery is considered a milestone in the history of stainless steel.

In the early 20th century, some Austrian scientists also made progress in the study of stainless steel. In 1912, Max Mauermann developed stainless steel containing 18% chromium and 8% nickel, which is considered to be the earliest type of 18-8 stainless steel.

Technological Breakthroughs and Industrial Applications

As research and applications of stainless steel continued to advance, the production and use of stainless steel experienced rapid growth after the mid-20th century. Steel mills and research institutions continuously improved the formulation and production processes of stainless steel, leading to its increasingly widespread use in various fields, including construction, food processing, chemical industry, medical equipment, aerospace, etc. There are numerous types of modern stainless steel, which can be adjusted in alloy composition and processing techniques according to specific application requirements, to meet various performance demands.

Classification and Characteristics

1. Classification by Crystal Structure

Stainless steel is classified into five major categories based on crystal structure: austenitic stainless steel (A1, A2, A3, A4, A5), ferritic stainless steel (F1), martensitic stainless steel (C1, C4, C3), duplex stainless steel, and precipitation-hardening stainless steel. Each type of stainless steel has its unique physical and chemical properties suitable for different applications. For example, austenitic stainless steel is widely used in kitchenware and medical instruments due to its excellent workability and corrosion resistance, while martensitic stainless steel is commonly used for manufacturing tools because of its high strength and hardness.

- Austenitic Stainless Steel: Contains 16%-26% chromium and less than 35% nickel. It typically has the highest corrosion resistance and is non-magnetic. Common types include 304L, 316L, 904L, etc. pressure cooker made of stainless steel

-Ferritic Stainless Steel: Contains 10.5%-27% chromium and no nickel. It is used in applications where corrosion resistance requirements are not high, such as in construction and automotive decoration. Common types include 434, 441, etc.

- Martensitic Stainless Steel: Typically contains 11.5%-18% chromium and less than 1.2% carbon, sometimes with nickel. It can be strengthened by heat treatment and is used in cutlery, surgical instruments, wrenches, turbines, etc. Common types include 416, 420, 431, etc. spanner/wrench

- Duplex Stainless Steel: A mixture of austenitic and ferritic stainless steel with a microstructure ratio of about 50:50. It exhibits better corrosion resistance to chloride than austenitic stainless steel. Common types include 2205, 2507, etc.

- Precipitation Hardening Stainless Steel: Has an austenitic or martensitic matrix and can be hardened by precipitation hardening treatment. Common types include 17-4PH, 15-5PH, etc.

2. Classification by Steel Grade

SAE steel grades are a set of steel number systems developed by the Society of Automotive Engineers. The 200, 300, 400, 500, and 600 series are commonly used in stainless steel grades.

- 200 Series: Chromium-Nickel-Manganese Austenitic Stainless Steel.

- 300 Series: Chromium-Nickel Austenitic Stainless Steel. Common types include 301, 304, 316, etc.

301: Good ductility, suitable for forming products. It can also be rapidly hardened through mechanical processing. Excellent weldability. Wear resistance and fatigue strength are superior to 304 stainless steel, used in products such as springs, steel structures, and wheel covers.
302: Corrosion resistance similar to 304, but with higher carbon content, resulting in better strength.
303: By adding small amounts of sulfur and phosphorus, it is easier to machine than 304.
304: Mainly available in two types: 18% chromium / 8% nickel and 18% chromium / 10% nickel stainless steel. Used in products such as corrosion-resistant containers, cutlery, furniture, railings, and medical equipment. The standard composition is 18% chromium plus 8% nickel. It is non-magnetic, but occasional weak magnetism may occur after processing when impurity levels are high. This weak magnetism can only be eliminated through heat treatment. It belongs to stainless steel that cannot change its microstructure through heat treatment methods.
304L: Shares the same characteristics as 304, but with lower carbon content, making it more corrosion-resistant and easier to heat treat. However, its mechanical properties are poorer, making it suitable for welded and less heat-treated products.
304N: Shares the same characteristics as 304. It is nitrogen-containing stainless steel. Nitrogen is added to improve the strength of steel.
309: It has better temperature resistance compared to 304.
309s: With higher amounts of chromium and nickel, it exhibits excellent heat resistance and oxidation resistance. It is used in products such as heat exchangers, boiler components, and jet engines.
310s: Containing the highest levels of chromium and nickel, it offers the best heat resistance and oxidation resistance, making it suitable for applications such as heat exchangers, boiler components, and electrical equipment.
316: Following 304, it is the second most widely used steel grade, primarily employed in the food industry and surgical instruments. The addition of molybdenum gives it a special corrosion-resistant structure. Due to its superior resistance to chloride corrosion compared to 304, it is also used as "marine steel". SS316 is typically used in nuclear fuel reprocessing equipment. Stainless steel grades with 18/10 composition also meet this application level. It is especially suited for corrosive environments such as chemical plants, coastal areas, shipbuilding, and construction materials.
316L: Due to its low carbon content, it is more corrosion-resistant and easier to heat treat. It is used in products such as chemical processing equipment, nuclear power generators, and cryogenic storage tanks.
321: Apart from reducing the risk of weld seam corrosion by adding titanium elements, its other properties are similar to 304. It is suitable for welding brewing equipment, steam pipes, and aerospace components.
347: Adding stabilizing element niobium, suitable for welding aerospace components and chemical equipment.

- 400 Series: Ferritic and Martensitic Stainless Steel. Common types include 409, 410, 420, 430, etc.

408: Good heat resistance, weak corrosion resistance, 11% Cr, 8% Ni.
409: Besides the addition of titanium to reduce the risk of weld seam corrosion, the most economical type (in the UK and US), commonly used for automotive exhaust pipes, belonging to ferritic stainless steel (chromium steel), suitable for welding, low cost, used in automotive exhaust pipes, and petroleum equipment.
410: Martensitic (high-strength chromium steel), good wear resistance, poor corrosion resistance, suitable for pumps. Its chemical composition contains 13% chromium, less than 0.15% carbon, and a small amount of other alloying elements. Raw material prices are relatively cheap, magnetic, and can be hardened by heat treatment. Common applications include bearings, medical devices, and knives.
416: Adding sulfur improves the machinability of the material.
420: Contains higher carbon, hardness, and higher strength, blade-grade martensitic stainless steel, similar to Brearley's stainless steel, the earliest stainless steel developed by British metallurgist Harry Brearley, capable of achieving a very bright finish, suitable for knives, springs, surgical instruments, razor blades, and valves.
430: Ferritic stainless steel, decorative, magnetic, used for automotive ornaments. Good formability, but poor heat resistance and corrosion resistance, suitable for fasteners, cutlery, and furniture. The standard chemical composition is 16-18% chromium, with low carbon content. This type of stainless steel is magnetic.
434: Contains molybdenum, so it has better corrosion resistance than 430, suitable for cutlery, wipers, and automotive decoration.
440: High-strength blade steel, slightly higher carbon content, after appropriate heat treatment, it can achieve higher yield strength, hardness can reach 58HRC, and belongs to the hardest stainless steel. The most common application example is "razor blades". There are three common types: 440A, 440B, 440C, and another type, 440F (easy-to-process type).

- 500 Series: Heat-Resistant Chromium Alloy Steel.

- 600 Series: Martensitic Precipitation Hardening Stainless Steel. Common types include 630 (17-4PH), etc.

-904L Stainless Steel is a low carbon, high alloy austenitic stainless steel designed for use in corrosive environments. It exhibits excellent resistance to sulfuric acid and other corrosive conditions, making it suitable for various applications including pressure vessels.

Conclusion

Stainless steel has traversed a rich evolutionary journey, evolving from ancient steel artifacts to the sophisticated alloys we utilize today. Its diverse classifications cater to myriad applications across industries, from construction to medicine, aviation to culinary arts. In the realm of horology, stainless steel stands out as a preferred material for watchmaking due to its durability, corrosion resistance, and aesthetic appeal.

Next section: The Application and Development of Stainless Steel in Watchmaking.

From Material of the Industrial Revolution to Modern Fashion Icon--Part one: The History and Evolution of Stainless Steel as a Metal Material