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QN1803 Stainless Steel: High-Performance Alternative to 304
2025-06-12
Overview: QN1803 (also called 304D or grade 1.4376) is a newly developed austenitic stainless steel from Tsingshan/Qingtuo. It is formulated with high nitrogen, high chromium and copper, and reduced nickel content to deliver higher strength and corrosion resistance at lower costthan standard 304. QN1803 is described as a “cost-effective alternative to traditional 304 Stainless Steel,” offering“superior corrosion resistance, high strength, and excellent wear resistance”. Its high-nitrogen, low-nickel design lowers alloy cost without compromising performance. The alloy is easy to process and weld, and meets international standards and food-grade certifications, making it suitable for global export.
High-Nitrogen, Nickel-Saving Alloy Composition
QN1803’s chemistry is tailored for performance and cost-efficiency. It contains Cr 17.5–19.5%, Cu 1.0–3.5%, and N 0.20–0.30%, with Ni just 2.0–3.5% (versus ~8% in 304). By contrast, 304 steel is ~18% Cr, 8% Ni, ~0.045% N, and only ~0.1% Cu. The extra nitrogen and chromium boost strength and pitting resistance, while added copper imparts antibacterial properties and better formability. Lower nickel content (and moderate manganese) significantly reduces material cost. In short, QN1803’s high-Ni-saving formula yields a stainless steel with corrosion and mechanical characteristics equal to or better than 304 at a lower alloy cost.
Mechanical Strength and Durability
QN1803 exhibits superior mechanical properties compared to 304. Typical values for cold-rolled sheet (0.5 mm) are: tensile strength ~747 MPa vs 670 MPa for 304, and yield strength ~432 MPa vs 290 MPa. Hardness is correspondingly higher (HV 230 vs 165). Elongation remains high (≈52% vs 59% for 304) despite the strength boos. In practical terms, QN1803’s yield is about 1.3× that of 304 while retaining ductility (elongation ≥45%). The result is a tougher, more fatigue- and wear-resistant material. It also welds and forms well: post-weld strength matches or exceeds 304, and cold-forming does not degrade corrosion resistance.
Key Mechanical Data:
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Tensile Strength: ~747 MPa (vs 670 MPa for 304).
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Yield Strength: ~432 MPa (vs 290 MPa).
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Elongation: ~52% (vs 58.5%).
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Hardness: HV230 (vs HV165).
Superior Corrosion Resistance
The alloy’s high Cr and N produce excellent corrosion performance. QN1803’s Pitting Resistance Equivalent Number (PREN) exceeds 19, matching or surpassing 304’s resistance (PREN≈18.5). In standardized tests, QN1803 even shows better corrosion resistance after cold forming (bending, stamping, etc.) compared to 304. It is highly resistant to dilute acids (HCl, H₂SO₄) and chloride-containing environments. For example, in neutral salt-spray (NSS) testing per GB/T standards, QN1803 showed no visible rust after 1000 hours. In the same test 304 would normally begin to corrode. This superior salt-spray endurance underlines QN1803’s reliability in harsh outdoor or marine conditions.
Corrosion Data:
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PREN: >19.0 (304 has ≈18.5).
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Salt-Spray Resistance: No rust after 1000 h NSS test.
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Acid/Chloride: Proven better uniform and pitting resistance than 304, even after forming
Food-Grade Safety and Antibacterial Properties
QN1803 is fully food-safe and even provides built-in antibacterial effect. The high purity and low heavy-metal levels meet EU, German LFGB and JIS standards for kitchenware and food equipment. Copper alloying (~1–3.5%) gives strong antimicrobial action: tests show a >99.9% sterilization rate within 4 hours (JIS standard). Combined with excellent corrosion resistance in typical food acids/salts, QN1803 is ideal for kitchen countertops, cookware, sinks and floor drains. For example, QN1803 passes national migration tests for heavy metals and exceeds 304 in weak-acid saline resistance. In water tanks and sanitary systems, copper also helps inhibit bacterial growth, making stored water healthier.
Figure: Stainless-steel cookware set. QN1803’s high corrosion resistance and copper-alloy content meet stringent food-grade and antibacterial standards (JIS/EU/LFGB) for kitchen and sanitary products.
Applications and Use Cases
QN1803’s combination of strength, corrosion resistance and cost-effectiveness makes it versatile across many industries. It is already in use for:
Construction & Architecture: Roofing, wall panels, curtain walls and decorative cladding benefit from QN1803’s high strength and weather resistance. Higher yield strength (exceeding mild steel grades) allows lighter gauge panels.
Piping and Infrastructure: Drainage and firefighting pipes, plumbing, gutters and sewage systems gain longer life due to the steel’s immunity to rust and acid corrosion. In gas pipelines or desulfurization towers, QN1803 resists sulfur-containing corrosion much better than 304.
Water Storage & Farming: Tanks, reservoirs and marine farming structures use QN1803 for its antibacterial copper content and saltwater durability. Its strength also supports heavy loads in livestock equipment.
Kitchen and Appliances: Countertops, sinks, cookware, and food machinery favor QN1803 for its food-grade safety. It endures weak acids and saline kitchen environments better than 304, and meets international hygiene standards.
Consumer & Commercial Products: Hardware doors, elevator panels, and decorative hinges or rails exploit QN1803’s higher hardness and wear resistance. Compared to 304 in door/gate applications, QN1803 maintains finish and shape under impact and wind loads. It also welds and polishes well for appliances and transport containers.
Figure: Stainless-steel gate hardware. QN1803 offers higher hardness and strength than 304 for architectural hardware and commercial fixtures, while providing superior corrosion resistance in outdoor environments.
Advantages Over 304 Stainless Steel
Compared to conventional 304, QN1803 delivers notable improvements in key areas:
Mechanical Properties: As noted, its tensile and yield strengths are roughly 15–30% higher than 304’s. Hardness and fatigue life are also improved, allowing thinner sections or lighter components for the same performance.
Corrosion Performance: QN1803 matches or exceeds 304’s corrosion resistance in all tests. Its higher PREN and sulfuric/chloride resistance mean it outperforms 304 especially in aggressive or formed conditions. It resists pitting and crevice corrosion even in kitchen and marine atmospheres, making it a more durable choice for outdoor and food-related uses.
Cost Efficiency: Thanks to the lower nickel and higher nitrogen/copper, QN1803 can cost up to ~20% less than 304 per ton (depending on market) while providing equal or better performance. Analysts note that “what 304 can do, 304D can also do, and the price is much cheaper”. Lower alloy cost and longer component life translate to lower total cost of ownership.
Food/Health Safety: QN1803 is certified for food-contact use. Its copper-enhanced, high-purity composition passes strict antibacterial and migration tests (EU, JIS, LFGB), which some 304 grades cannot. This makes it especially attractive for kitchen, sanitary and water applications requiring certified safety.
In summary, QN1803/304D stainless steel offers engineers and procurement specialists a high-performance, food-safe, and cost-effective material. Its combination of high nitrogen alloying, high Cr/Cu, medium Ni gives it mechanical strength and corrosion resistance that meet or exceed 304’s, while saving on nickel costs. The alloy’s proven reliability in international standards tests (NSS 1000h, JIS antibacterial, etc.) and its broad application range make it a strategic alternative for modern stainless steel products.