# Alloy patents: why different numerical ranges may not establish inventive step Korean Supreme Court case 2023Hu10637 examines composition, intended use and evidence of technical effects in welding-wire claims. Source: https://www.iplexlaw.co.kr/en/blog/brunch-case-1838 HOME / NEWS & INSIGHTS NEWS & INSIGHTS Alloy patents: why different numerical ranges may not establish inventive step Korean Supreme Court case 2023Hu10637 examines composition, intended use and evidence of technical effects in welding-wire claims. Patents 2026.10.16 published IPLEX 5 min read The dispute and the governing approach On 12 August 2026, Korea’s Supreme Court dismissed the patentee’s appeal in case 2023Hu10637, leaving the adverse inventive-step finding intact. The claims, corrected on 24 February 2022, concerned stainless-steel flux-cored wire for LNG tanks. The inquiry was whether a skilled person could bridge the differences from the prior art, considering composition ranges and relationships, microstructure, inherent properties, use and effects together. Claims 1–2 were assessed against prior invention 1; claims 3–4 against prior invention 4. Claims 1–2: overlapping composition and a stated use The components were substantially the same, most ranges overlapped or were contained within the claimed ranges, and relation 1 was satisfied. The claims specified a 9% nickel-steel tank base metal, whereas prior invention 1 concerned SUS316 and SUS316L. Yet the description supplied no mechanism, microstructure or other technical basis showing special suitability for welding 9% nickel steel. Its stated problem instead contemplated welding without restricting the structural-steel base material. A new use label therefore did not establish a distinct material property here. Manganese and impurities: what did the limits achieve? The manganese ranges were 3.0–8.0 wt% in claims 1–2 and 1.0–3.0 wt% in prior invention 1, sharing the 3.0 boundary. Both disclosures treated manganese as a deoxidizer and linked the lower bound to sufficient deoxidation. Limiting phosphorus plus sulfur to 0.1 wt% or less likewise reflected routine impurity control: both disclosures associated these impurities with hot cracking or recommended minimizing them. The description lacked examples or experimental results demonstrating a critical effect inside versus outside these limits. Claims 3–4: a small gap and low-temperature properties Prior invention 4 satisfied relations 2 and 3 and largely shared the claimed composition. It used other stainless-steel base metals rather than 9% nickel steel. Its manganese values, 1.51 and 1.44 wt%, were outside the claimed 2.0–5.0 wt%, but only 0.49 and 0.56 percentage points below the minimum, without evidence of a critical effect. The claims also specified Charpy impact values of 33–45 J at −196°C. Although prior invention 4 did not state that value, its tensile strengths of 640 and 650 MPa fell within the claimed 640–740 MPa range, and the record disclosed no special difference in cryogenic impact behavior. Drafting and dispute strategy All four claims lacked inventive step on this record. The decision does not say that every narrow range or small numerical gap is necessarily obvious. A useful specification connects the chosen limits to the alloy’s structure, operating conditions and resulting effects. Matched comparisons, including relevant values outside a range, can make that explanation persuasive; the lesson is to substantiate technical significance, not to assume that a different number or a new application alone establishes patentability. The original figure labels and forms are preserved; the text explains the facts and the court’s reasoning. Read the Korean source This article reflects the information available when it was published. Contact us to discuss your circumstances. Discuss this topic ↗ All articles Related service: Patents & utility models ↗ Related service: IP disputes & appeals ↗ ON THIS PAGE The dispute and the governing approach Claims 1–2: overlapping composition and a stated use Manganese and impurities: what did the limits achieve? Claims 3–4: a small gap and low-temperature properties Drafting and dispute strategy TALK TO IPLEX Discuss your IP questions We consider your technology and business needs together. ↗ Contact us Older PaTH Attention: encoding the path between tokens ↗ Related insights Patents 2026.10.15 Who must prove that a patent was filed without entitlement? 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