M390 Bohler PM Stainless Steel: Properties, Uses, Manufacturing Insights

M390 Bohler PM Stainless Steel is a top-tier material famous for its exceptional wear resistance and corrosion resistance. Developed by Bohler-Uddeholm, this powder metallurgy (PM) stainless steel is a favorite in industries like knife making, medical, and aerospace. In this guide, we’ll explore its key properties, real-world applications, how it’s made, and how it stacks up against other materials—helping you choose it wisely for your projects.

1. Key Material Properties of M390 Bohler PM Stainless Steel

The outstanding performance of M390 starts with its unique chemical composition, which shapes its impressive physical properties, mechanical properties, and other critical traits.

Chemical Composition

M390’s formula is tailored for strength and resistance. Key elements include:

• Carbon content: 1.9% (boosts hardness and edge retention)
• Chromium content: 20% (delivers excellent corrosion resistance)
• Molybdenum content: 4% (enhances wear resistance and toughness)
• Vanadium content: 4% (forms hard carbides for abrasion resistance)
• Tungsten content: 1.5% (improves high-temperature strength)
• Cobalt content: 1.5% (increases hardness and heat resistance)
• Trace amounts of manganese, silicon, phosphorus, and sulfur (for better processing)

Physical Properties

Mechanical Properties

After proper heat treatment, M390 delivers industry-leading performance:

• Tensile strength: 2,000 MPa
• Yield strength: 1,800 MPa
• Elongation: 4-5% (in 50 mm)
• Hardness: 60-62 Rockwell C (HRC), ~700 Vickers, ~580 Brinell
• Fatigue strength: ~800 MPa (at 10⁷ cycles)
• Impact toughness: 15-20 J (at room temperature, Charpy V-notch)

Other Critical Properties

• Corrosion resistance: Excellent—resists saltwater, chemicals, and staining (thanks to high chromium).
• Wear resistance: Top-tier—ideal for cutting tools and parts that see heavy friction.
• Abrasion resistance: Superior to most tool steels (due to vanadium carbides).
• Stain resistance: Won’t rust easily, even in damp environments.
• Edge retention: Exceptional—stays sharp longer than standard stainless steels (a must for knives).
• Heat treatability: Easy to heat treat to achieve maximum hardness without cracking.

2. Real-World Applications of M390 Bohler PM Stainless Steel

M390’s unique mix of strength and resistance makes it perfect for demanding uses. Here are its most common applications:

Knife Making

• Tactical knives: Used by military and law enforcement—handles rough use and resists corrosion in harsh conditions.
• Hunting knives: Stays sharp through cutting meat and bone, and won’t rust when exposed to blood or rain.
• Kitchen knives: High-end chef’s knives use M390 for long-lasting sharpness and easy cleaning (resists food acids).

Case Example: A leading knife brand (Benchmade) used M390 in its 940-1 knife. Users reported the blade stayed sharp 3x longer than knives with standard 154CM steel, and it showed no rust after 6 months of outdoor use.

Medical Instruments

• Surgical instruments: Scalpels and forceps made from M390 resist corrosion from sterilization (autoclaving) and stay sharp for precise cuts.
• Dental instruments: Drills and scalers handle repeated use without wearing down, and they’re safe for oral tissues (non-toxic).

Aerospace & Automotive Industries

• Aerospace: High-strength components like engine parts and fasteners—M390 resists wear from high speeds and temperature changes.
• Automotive: High-performance parts (e.g., racing engine valves) and wear-resistant components (e.g., brake rotors for sports cars) that need to last under extreme stress.

Industrial Tools

• Cutting tools: Milling cutters and drills that cut through hard metals without dulling.
• Punches and dies: Used in manufacturing to shape metal—M390’s abrasion resistance means less tool replacement.

3. Manufacturing Techniques for M390 Bohler PM Stainless Steel

M390 is made using powder metallurgy (PM)—a process that creates a uniform, high-quality material. Here’s how it’s done:

1. Powder Metallurgy Core Steps

• Atomization: Molten M390 alloy is sprayed into tiny droplets (10-100 μm) using high-pressure gas. These droplets cool quickly to form pure, uniform powder.
• Compaction: The powder is pressed into molds (e.g., bar shapes) under high pressure (500-800 MPa) to create a “green compact” (a solid but porous piece).
• Sintering: The green compact is heated to 1,200-1,300°C in a vacuum furnace. The powder particles fuse together, eliminating pores and creating a dense, strong material.

2. Heat Treatment

• Austenitizing: Heat the sintered steel to 1,050-1,100°C and hold for 30-60 minutes. This changes the metal’s structure to “austenite” (a ductile phase).
• Quenching: Cool the steel quickly (in oil or air) to lock in a hard structure called “martensite.”
• Tempering: Reheat the steel to 180-220°C for 2-3 hours. This reduces brittleness while keeping high hardness (60-62 HRC).

3. Machining & Surface Treatment

• Machining processes:
• Grinding: Uses abrasive wheels to shape the steel (e.g., knife blades) with high precision.
• Milling: Cuts complex shapes (e.g., medical instruments) using rotating cutters.
• Turning: Creates cylindrical parts (e.g., tool shafts) on a lathe.
• Surface treatment:
• Polishing: Buffs the surface to a smooth finish (for knives or medical tools).
• Coating: PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition) coatings add extra wear resistance (e.g., a titanium nitride coating for cutting tools).

4. Quality Control

• Hardness testing: Uses Rockwell or Vickers testers to ensure the steel meets 60-62 HRC.
• Microstructure analysis: Examines the metal under a microscope to check for uniform carbide distribution (critical for wear resistance).
• Dimensional inspection: Uses calipers or 3D scanners to ensure parts match design specs.

4. Case Study: M390 in Medical Surgical Scalpels

A medical device manufacturer wanted to improve its surgical scalpels. Their old scalpels (made from 440C steel) dulled after 10-15 uses and rusted after repeated autoclaving. They switched to M390, and here’s what happened:

• Performance: The M390 scalpels stayed sharp for 50+ uses—reducing the need to replace blades during surgeries.
• Corrosion Resistance: No rust or staining after 100 autoclave cycles (vs. 440C, which showed rust after 30 cycles).
• Cost Savings: The manufacturer saved 20% on blade replacement costs and received positive feedback from surgeons about precision.

5. M390 Bohler PM Stainless Steel vs. Other Materials

How does M390 compare to other popular materials? Let’s break it down:

Application Suitability

• Knife Making: M390 is better than 154CM/S30V (longer edge retention, better corrosion resistance).
• Medical Tools: Superior to HSS (resists sterilization corrosion) and cheaper than titanium.
• Aerospace: Better than HSS for wear-resistant parts, but titanium is lighter for weight-sensitive components.
• Industrial Tools: Outperforms 154CM in cutting hard metals, though it’s more expensive.

Yigu Technology’s View on M390 Bohler PM Stainless Steel

At Yigu Technology, we recognize M390 as a game-changer for high-demand applications. Its powder metallurgy design gives it unmatched wear and corrosion resistance, making it ideal for our clients in medical device and high-performance manufacturing. We often recommend it for custom knife blades and precision tools, as it balances durability and reliability. While it costs more than standard steels, its long lifespan reduces overall project costs—aligning with our goal of delivering sustainable, cost-effective solutions.

FAQ

1. Is M390 Bohler PM Stainless Steel rust-proof?

No, but it’s highly rust-resistant. Its 20% chromium content forms a protective oxide layer that prevents rust in most environments (e.g., water, salt spray). However, it may show minor staining if left in harsh chemicals for long periods—regular cleaning avoids this.

2. Can M390 be sharpened easily?

Yes, but it requires harder abrasives (e.g., diamond stones) than standard steels. Once sharpened, it holds an edge much longer, so you’ll sharpen it less frequently—saving time in the long run.

3. Is M390 suitable for food contact (e.g., kitchen knives)?

Absolutely. M390 is non-toxic and resists corrosion from food acids (e.g., tomatoes, citrus). It’s easy to clean, and its smooth surface doesn’t trap food particles—meeting food safety standards worldwide.