PTAB

IPR2015-00150

Bohler EDelSTAhl GmbH & Co KG v. ROvaLMA SA

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Petition
petition

1. Case Identification

2. Patent Overview

  • Title: Process for Setting the Thermal Conductivity of a Steel, Tool Steel, in Particular Hot-Work Steel, and Steel Object
  • Brief Description: The ’056 patent describes a process for achieving a high thermal conductivity (greater than 42 W/mK) in hot-work steel. The process steps are defined by selecting a steel with a specific chemical composition, particularly limiting chromium content to below 2% and controlling the amounts of carbide-forming elements like Molybdenum (Mo), Tungsten (W), and Vanadium (V).

3. Grounds for Unpatentability

Ground 1: Obviousness over a single Swiss patent - Claims 1-4 are obvious over CH '893.

  • Prior Art Relied Upon: Swiss Patent 165,893 ("CH '893").
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that the process claims of the ’056 patent are met simply by providing a steel of a specific composition. CH '893 disclosed two hot-work tool steel compositions ("Steel 1" and "Steel 2") with very low chromium ("preferably not present at all"), carbon content between 0.27-0.40%, and a combined Mo+W+V content of 3.32-3.46%. Petitioner contended these compositions fall squarely within the compositional limitations of claims 1-4 as construed, including the requirements for dependent claims 2 and 3 which require even lower chromium levels. Petitioner asserted that CH '893's teaching that its steel is "noticeably resistant against temperature variations" inherently suggests the high thermal conductivity recited in the claims.
    • Motivation to Combine (for §103 grounds): Not applicable (single reference ground).
    • Expectation of Success (for §103 grounds): Not applicable (single reference ground).

Ground 2: Obviousness over a single European patent - Claims 1 and 4 are obvious over EP '813.

  • Prior Art Relied Upon: European Patent 0,707,813 ("EP '813").
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that EP '813 explicitly taught the core concept of the ’056 patent: that low-chromium ferritic steels possess higher thermal conductivity compared to high-chromium steels. EP '813 disclosed steel compositions for hot-work applications (e.g., compositions 8 and 32) that meet the key compositional requirements of claims 1 and 4, including low chromium (0.98-1.07%), a combined Mo+W+V content over 2%, and other specified alloying elements. Petitioner asserted that providing one of these known high-conductivity, low-chromium steel compositions would inherently perform the claimed process of "setting" a high thermal conductivity.
    • Motivation to Combine (for §103 grounds): Not applicable (single reference ground).
    • Expectation of Success (for §103 grounds): Not applicable (single reference ground).

Ground 3: Obviousness over European and Swiss patents - Claims 1-4 are obvious over EP '813 in view of CH '893.

  • Prior Art Relied Upon: EP '813 and CH '893.

  • Core Argument for this Ground:

    • Prior Art Mapping: EP '813 provided the general principle and knowledge in the art that reducing chromium content increases thermal conductivity in steel. CH '893 provided specific examples of low-chromium hot-work tool steels that met nearly all the compositional limitations of the challenged claims. While EP '813 disclosed a C+N+B content of 0.25-0.26%, CH '893's Steel 2 disclosed a carbon content of 0.27%, representing a minor and obvious variation.
    • Motivation to Combine (for §103 grounds): A POSITA would combine the teachings to achieve the known benefits of both references. Motivated by the objective of creating a hot-work steel with high thermal conductivity (taught by EP '813), a POSITA would have looked to known hot-work steel compositions, such as those in CH '893, and recognized that their inherent low-chromium content would achieve the desired property. The references shared overlapping objectives of high performance at elevated temperatures.
    • Expectation of Success (for §103 grounds): A POSITA would have a high expectation of success because EP '813 provided the scientific principle (low Cr = high conductivity), and CH '893 provided a working example of a suitable base alloy.

  • Additional Grounds: Petitioner asserted additional obviousness challenges against claims 1-4 based on EP '813 in view of Japanese publications JP '241, JP '650, and JP '706. These grounds relied on a similar theory: combining EP '813's teaching on thermal conductivity with other known low-chromium tool steel compositions from the Japanese references to achieve predictable improvements in properties like abrasion resistance and tool lifespan.

4. Key Claim Construction Positions

  • Petitioner dedicated significant argument to construing the process steps of the claims not as manufacturing methods, but as being entirely satisfied by the selection of a steel with a specific composition.
  • Based on the patent’s specification and its prosecution history—where the Examiner repeatedly rejected claims under 35 U.S.C. §112 until specific compositional limitations were added—Petitioner argued that the only enabled way to practice the invention is to provide a hot-work steel meeting the recited elemental ranges.
  • For example, Petitioner argued that "metallurgically creating an internal structure" (step 2/2a) and "selecting" surface/volume fractions (step 3) are both satisfied by providing a steel with <2% Cr and specified C/N/B content. Similarly, "setting the thermal conductivity" to >42 W/mK (step 4) is construed as providing a steel with the full set of compositional ranges disclosed in the specification as achieving that result.

5. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-4 of Patent 8,557,056 as unpatentable.