POSCO v. ArcelorMittal

1. Case Identification

• Case #: IPR2019-01275
• Patent #: 9,708,683
• Filed: June 28, 2019
• Petitioner(s): POSCO
• Patent Owner(s): ARCELORMITTAL
• Challenged Claims: 1-11

2. Patent Overview

• Title: Coated Steel Product and Method for Preparing Same
• Brief Description: The ’683 patent discloses a coated steel stamped product made from a base steel with an aluminum alloy pre-coating. The product is formed by a hot-stamping process that causes an alloying reaction, resulting in a final coating with a specific four-layer microstructure proceeding outwards from the steel: an Interdiffusion layer, an Intermediate layer, an Intermetallic layer, and a Superficial layer.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1-2 - Claims 1-2 are anticipated by Cornette under 35 U.S.C. §102.

• Prior Art Relied Upon: Cornette (SAE Technical Paper 2001-01-0078).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Cornette, which describes a pre-coated boron steel for hot forming automotive parts, disclosed every element of claims 1 and 2. Cornette was alleged to teach a coated steel stamped product whose final coating results from an alloying reaction during heat treatment. Petitioner asserted that Cornette’s Figure 22, a scanning electron microscope (SEM) image, showed a multiphase alloy layer with a four-layer structure directly corresponding to the four layers recited in claim 1. Cornette also explicitly stated the final coating thickness is "typically about 40 µm," satisfying the ">30 micrometers" limitation, and its SEM image allegedly showed an interdiffusion layer thickness of less than 15 micrometers. For dependent claim 2, Petitioner contended Cornette's SEM image showed the claimed intermetallic and superficial layers are quasi-continuous across at least 90% of their level.
  • Key Aspects: Petitioner emphasized that Cornette was not considered by the Examiner during prosecution and that its SEM image, while not explicitly labeling the four layers, was directly analogous in structure and appearance to the labeled Figure 1 of the ’683 patent.

Ground 2: Obviousness of Claims 3-4, 6-7, and 10 - Claims are obvious over Cornette in view of Laurent.

• Prior Art Relied Upon: Cornette (SAE Technical Paper 2001-01-0078) and Laurent (Patent 6,296,805).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that while Cornette taught the foundational coated steel product, it only provided acceptable ranges for the base steel's composition and did not specify how to achieve certain properties. Laurent, a reference in the same field, was asserted to supply these missing details. Specifically, Laurent allegedly disclosed a base steel composition with specific weight percentages for carbon, manganese, silicon, and other elements that fall within the ranges recited in claims 3 and 4. Laurent was also argued to teach the specific ratio of titanium to nitrogen required by claim 6, the pre-coating composition of claim 7, and the process parameters (e.g., cooling speed) needed to obtain the "full martensitic structure" of claim 10.
  • Motivation to Combine: A POSITA would combine Cornette and Laurent because both relate to pre-coated boron steels for hot-stamped automotive parts. A POSITA seeking to implement Cornette's general teachings would look to a reference like Laurent to find specific, proven compositions and process parameters to ensure a predictable and successful result, thereby avoiding undue experimentation with Cornette’s broad ranges.
  • Expectation of Success: Petitioner asserted a high expectation of success, as Laurent's specific steel composition values fall squarely within the acceptable ranges disclosed by Cornette, making the combination a predictable optimization of a known product.

Ground 3: Obviousness of Claim 5 - Claim 5 is obvious over Cornette in view of Nishibata.

• Prior Art Relied Upon: Cornette (SAE Technical Paper 2001-01-0078) and Nishibata (WO 2004/106573).
• Core Argument for this Ground:
  • Prior Art Mapping: Claim 5 requires the base steel to comprise 20 ppm or less of sulfur. Petitioner noted that Cornette’s steel could have up to 80 ppm of sulfur. Nishibata, however, was argued to explicitly teach a boron steel for hot-forming with a sulfur content of 20 ppm, meeting the claim limitation.
  • Motivation to Combine: A POSITA would have been motivated to modify Cornette's steel to have the lower sulfur content taught by Nishibata. It is well known in the art of metallurgy that reducing impurities like sulfur improves the mechanical properties of steel, particularly its formability. Therefore, a POSITA would seek to use a base steel with the lowest possible sulfur content, as exemplified by Nishibata, to improve the final product.
  • Expectation of Success: Success would be expected because lowering a known impurity is a routine and predictable method for improving steel quality, and Nishibata provided a concrete example of a suitable low-sulfur steel composition.
• Additional Grounds: Petitioner asserted additional obviousness challenges, including that claims 8 and 11 are obvious over Cornette alone; claim 9 is obvious over Cornette in view of Somani; and claim 11 is obvious over combinations including Cornette, Laurent, EP Laurent, FR Laurent, and Engels.

4. Key Claim Construction Positions

• "interdiffusion" (Claim 1): Petitioner proposed this term be construed as "intermingling of the molecules of two or more substances," which in the context of the ’683 patent is caused by an alloying reaction. This construction was central to Petitioner's argument that the coating's formation is a known alloying process disclosed in the prior art.
• "Interdiffusion layer" (Claim 1): Based on its construction of "interdiffusion" and dictionary definitions, Petitioner proposed this term meant "a layer, adjacent to a base material, formed from the intermingling of the molecules of two or more substances." This was critical for mapping the unlabeled layers shown in Cornette’s SEM image to the claimed coating structure.
• Other Layer Terms (Intermediate, Intermetallic, Superficial): Petitioner argued these terms were not defined in the patent and should be given their plain and ordinary meanings (e.g., "Intermediate layer" means "a layer between two other layers").

5. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1-11 of the ’683 patent as unpatentable.