스트립 나이프용 공구강 MTC(밀시트) 올바르게 읽기: 화학 성분, 경도 및 추적성을 위한 실무 QA 체크리스트

핵심 요약 (Quick Answer): 스트립 나이프용 공구강 MTC(밀시트)를 해석하려면 먼저 문서 상단(Header)에서 EN 10204 3.1 검사증명서 유형, 공급사 정보, 강종(Steel grade) 및 차저(Heat) 번호를 확인하십시오. 그런 다음 구매 발주서(PO) 또는 사양서와 화학 성분표를 대조 검증합니다(기준 표준으로 ASTM A681 또는 ISO 4957 활용). 경도 균일성은 9점 경도 맵(ASTM E18 기준: 상/중/하 × 양 끝/중앙/양 끝)을 통해 검증하며, 절삭 날의 성능이 극히 중요한 경우 탈탄층 검사(ASTM E1077)를 추가하십시오. 완벽한 추적성(Traceability) 체계를 구축하려면 Heat 번호가 MTC, 코일 태그(Coil tag) 및 내부 로트(Lot) 관리 기록과 상호 일치해야 합니다.

스트립 나이프 제조에서 공구강 MTC(밀시트)는 신속하고 입증 가능한 입고 (Receiving) 의사결정을 내리는 데 도움이 되고, 코일을 슬리팅, 연삭 및 내부 로트(Lot)로 전환한 후에도 추적성(Traceability)을 지속적으로 증명할 수 있을 때에만 유효합니다. 본 실무 체크리스트는 Maxtor Metal QA 및 금속 공학 팀이 작성한 것으로, 산업용 나이프 제조, 맞춤형 강종 선정, 그리고 공급사와 구매사 간의 서류, 태그 및 검증 항목을 일치시키는 엄격한 품질 관리 프로토콜에 대한 15년 이상의 전문 노하우를 바탕으로 작성되었습니다.

• 목적: enable fast, reliable acceptance decisions for strip blades
• Scope: EN 10204 3.1 focus (EN 10204 3.1 certificate), heat number, chemistry, hardness uniformity
• Standards referenced: EN 10204, ASTM E18, ASTM E1077, ASTM A681/ISO 4957
• Why reading tool steel MTC matters to QA, uptime, and FPY
• How this checklist reduces retests, scrap, and downtime

Key takeaway: Treat the MTC as the starting point for acceptance: it anchors traceability and declared results, but your receiving checks decide whether the coil is safe to process.

MTC 검사증명서(밀시트) 기초

What an EN 10204 3.1 covers

An EN 10204 Type 3.1 inspection certificate is the common “mill test certificate / material test certificate” format used in metals supply. In simple terms, it’s the manufacturer’s declaration that the delivered product complies with the order, and it includes test results tied to the test unit.

This is the EN 10204 3.1 certificate your traceability system ultimately points back to.

For the formal definitions and document types, refer to EN 10204:2004 directly—available through official standards bodies such as BSI (EN 10204:2004) or your regional standards authority. The standard defines all document types (2.1, 2.2, 3.1, 3.2) and the authorization requirements for each.

Checklist (3.1 basics):

• Certificate type is explicitly shown as EN 10204 3.1.
• It includes measured results (not just “conforms”).
• It is signed/validated by the manufacturer’s authorized inspection representative.

Heat number and traceability linkage

For strip blades, the heat number is the shortest path to “Do we know exactly what this coil is?” It is the core of heat number traceability in coil-based supply. It should link:

• the MTC (declared chemistry + tests)
• the coil tag / packaging label
• your receiving record
• the internal lot numbers you create after slitting, leveling, or edge preparation

Receiving checklist (traceability linkage):

• Heat number on MTC matches the heat/heat-lot shown on the coil tag.
• Coil identifier (coil no., tag no., reel no.) is recorded on your receiving log.
• Your internal lot IDs inherit the heat number and keep it attached through WIP.

3.1 vs 3.2 vs 2.2

Use this as a decision shortcut:

• 2.2: declaration of compliance based on non-specific inspection (good for low-risk use; limited for audits).
• 3.1: manufacturer-issued inspection certificate with test results (typical baseline for industrial tool steels).
• 3.2: inspection certificate with third-party or purchaser’s representative involvement/witnessing (use when the risk or contract demands it).

공구강 MTC의 화학 성분 검증 방법 — 및 PMI(성분분석)를 넘어 정밀 분석이 필요한 시점

D2/M2/O1 acceptance bands

A tool steel MTC is not “good” because it lists numbers—it’s good because the numbers match what you ordered.

Practical acceptance rule:

• Your acceptance bands should come from your PO/spec callout, typically referencing a tool-steel material standard such as ASTM A681 또는 ISO 4957:2018.

Reference source: ASTM A681 / ISO 4957 standard chemistry composition limits.

Checklist (chemistry acceptance):

• Grade is stated clearly (e.g., D2, 엠2, O1) and matches the PO.
• Chemistry table includes the critical alloying elements for that grade.
• Heat number on the chemistry report matches the heat number on the certificate header.

For a detailed framework on how material grade validation — including heat-treatment batch records and XRD-based retained austenite verification — is specified for blade strip steel at the incoming stage, see Validating 440C Dicer Replacement Blades at HRC 56–58.

Pro tip: For incoming coils intended for strip blades, set a “stop the line” rule for grade ambiguity (for example, ambiguous equivalents or missing grade designation). It’s almost always cheaper than chasing performance scatter later.

PMI vs spark-OES/ICP-OES

Positive Material Identification (PMI) is often treated as a universal answer. It isn’t.

• PMI/XRF is strong for confirming alloy family and many elements, but it’s limited for carbon.
• Spark-OES and ICP-OES are typically used when you need more complete chemistry, including carbon-critical acceptance decisions.

Checklist (use the right method):

• Use PMI/XRF to screen: “Is this broadly the correct alloy family?”
• Use spark-OES or ICP-OES when the acceptance hinges on carbon-sensitive outcomes (hardness response, carbide network behavior), or when the contract requires lab confirmation.
• Document the method and instrument ID in the receiving record so results are auditable.

Resolve discrepancies to PO/spec

When chemistry results conflict (MTC vs your test vs supplier re-test), the fastest way to avoid downtime is to follow a written escalation path.

Discrepancy-resolution checklist:

1. Freeze the identity: confirm heat number + coil tag + sample location (head/mid/tail).
2. Confirm the reference: pull the PO/spec revision and identify which standard governs (e.g., ASTM A681 / ISO 4957).
3. Confirm methods: PMI vs OES vs ICP-OES; note detection limits and whether carbon was actually measured.
4. Re-sample intentionally: take a second sample from a different location and document chain-of-custody.
5. Decide action: accept, hold for disposition, downgrade use, or reject—based on the governing spec and risk.

경도 균일성이 평균값보다 중요한 이유 — 및 스트립/절삭 날에서의 경도 맵 작성 방법

For Rockwell testing, cite the official method: ASTM E18 Rockwell hardness test method. For practical context on why thickness/support matter, NIST’s guidance is a useful companion: NIST Rockwell hardness recommended practice.

Supply condition: Annealed vs. Pre-hardened

Before evaluating hardness values, clarify the delivery state on the PO/MTC:

• Annealed strip (Soft): Shipped in a spheroidized annealed state for severe forming, slitting, or punching before final heat treatment.
• Pre-hardened / Hardened & Tempered strip: Delivered at working hardness for direct grinding, edging, or light slitting without subsequent full quenching.

Mixing up delivery conditions is a common source of false rejects and false accepts — always confirm with the MTC header what condition the material is in before applying any hardness acceptance limit.

Strip sampling map: edge–center–edge; head/mid/tail

Hardness scatter in strip often hides in two directions:

• Across the width (edge-to-edge differences from processing, decarb, or leveling)
• Along the length (head/mid/tail differences from heat treatment variation or coil-end effects)

Checklist (minimum map that still finds problems):

• Sample at head / mid / tail.
• At each length position, test edge / center / edge.
• Record location IDs so a future complaint can be traced back to the zone.

Setup validity: thickness, spacing, support

A hardness number is only actionable if the test setup is valid for the strip geometry.

Setup checklist:

• Confirm you are using a Rockwell scale appropriate for the strip thickness.
• Ensure the specimen is flat and well supported on the proper anvil; avoid rocking.
• Keep indentations far enough from edges and from each other to avoid interaction.
• If your strip is thin, don’t “solve it” by stacking layers—control the method instead.

Interpret spread and actions

Don’t just look at the average. Look at the spread.

Interpretation checklist:

• If head/mid/tail shift together, suspect batch heat treatment 또는 process-window drift.
• If edges are consistently lower than center, suspect decarburization or edge conditioning effects.
• If one zone is off, isolate that zone in WIP routing (don’t blend lots).

Action checklist:

• Accept: hardness meets PO targets and spread is within your internal control limit.
• Hold / retest: hardness is borderline or spread suggests a localized issue.
• Reject / disposition: hardness is out of spec, or spread indicates non-uniformity that will create FPY loss.

탈탄(Decarburization) 및 조직 균일성

Detect and measure per ASTM E1077

If strip edges are soft, chip early, or don’t hold a stable grind, decarburization is a prime suspect—especially in thin sections where the surface zone is a larger fraction of the cross-section.

ASTM’s method for estimating decarb depth is ASTM E1077 — Standard Test Methods for Estimating the Depth of Decarburization of Steel Specimens.

Checklist (what to request/report):

• Sample location and orientation (edge vs center; head/mid/tail if relevant).
• Whether results are reported as total 그리고 partial decarburization depth.
• Metallography prep and etching method (so results are comparable across labs).

Impact on hardness and mitigation

Decarb turns into performance scatter because it shifts the hardness profile near the working surface.

Impact checklist:

• Softer surface zone → faster wear, unstable edge, unpredictable grinding response.
• Edge zone affected → failures show up as chipping or rapid dulling even when “bulk hardness” looks OK.

Mitigation checklist:

• Set decarb limits on the PO when the application is edge-sensitive.
• Control incoming verification for high-risk lots (new supplier, process change, unusual thickness).
• After secondary processing (slitting, grinding, heat treatment), re-verify hardness and surface condition before releasing to production.

품질 문서화 및 추적성 표준 작업 절차서(SOP)

Link MTC, coil tags, internal lots

A practical SOP connects physical identity to records so you can pass audits and also troubleshoot downtime quickly.

Checklist (minimum traceability chain):

• Archive the MTC PDF with a filename that includes supplier + grade + heat number.
• Photograph or scan the coil tag on receipt.
• Assign internal lot numbers that preserve the heat number association.

Engineering Note: If your traceability SOP needs to align with coil supply format specifications — including reel dimensions, lot splitting conventions, and documentation requirements — see Maxtor Metal’s reference page on industrial blade strip steel in beveled reels for form-factor and traceability documentation standards.

If your traceability review also involves coil length planning and changeover scheduling, see OEE and Profit Gains from Reducing Coil Change Frequency for the supply-side consistency controls that make longer runs reliable.

Retest records and change control

Retests are unavoidable; uncontrolled retests are expensive.

Checklist (retest discipline):

• Record retest triggers (what failed, where, and why you retested).
• Store test method, instrument, operator, and sample location.
• Tie retest results to a disposition decision (accept/hold/reject) and keep the revision history.
• If the PO/spec changes, lock the revision used for acceptance of each lot.

Supplier collaboration for verification

Collaboration here doesn’t mean marketing—it means preventing “paper-compliant, performance-unstable” material from entering production.

Practical collaboration checklist:

• Align on what the 3.1 must include (heat no., grade/spec callout, chemistry, hardness where applicable).
• Agree on a discrepancy path: who re-tests, with what method, and how chain-of-custody is documented.
• Lock a shared definition of “equivalent grade” acceptance (or forbid it unless approved).

Maxtor Metal provides customers with pre-aligned documentation packages — including certificate format templates, coil tag conventions, and verification record structures — so that traceability decisions remain consistent after slitting, leveling, and lot splitting. Customers running formal incoming QA programs can request the documentation alignment checklist from the Maxtor Metal technical team before the first shipment.

Audit & Re-verification Triggers

To prevent quality issues from slipping into production, establish clear conditions that trigger a mandatory joint audit or secondary lab re-verification:

• New Supplier / Subcontractor First Lot: Mandatory complete chemistry (OES) and 9-point hardness mapping on the initial 3 production heats.
• Process Change Notification (PCN): Any declared change in supplier annealing, heat treatment furnace, or slitting line parameters.
• Consecutive Hardness or Microstructure Deviations: Occurrence of edge-to-center hardness scatter exceeding ±1.5 HRC across 3 consecutive coil lots.
• Unexplained Production Tooling Failures: Immediate joint root-cause review if field blades exhibit premature micro-chipping or rapid edge dulling despite “paper-compliant” MTCs.

FAQs:

Q: 스트립 나이프용 공구강 MTC(밀시트)를 신속하게 해석하는 방법은 무엇인가요?

A: 문서 상단(Header)부터 확인하십시오. EN 10204 3.1 검사증명서, 공급사, 강종 및 차저(Heat) 번호를 확인합니다. 그 다음 화학 성분표가 구매 발주서(PO)/사양서와 일치하는지, Heat 번호가 코일 태그와 연동되어 있는지 검증합니다. 마지막으로 간단한 경도 맵(상/중/하 × 양 끝/중앙/양 끝)을 통해 경도 균일성을 최종 확인하십시오.

Q: EN 10204 3.1과 3.2 검사증명서(밀시트)의 차이점은 무엇인가요?

A: 3.1 증명서는 제조사에서 시험 성적 결과와 함께 발급하며 공인된 검사代表가 서명합니다. 3.2 증명서는 계약 조건에 따라 독립적인 제3자(외부 검사기관) 또는 구매자 대리인의 참관 및 검증이 추가됩니다. 제품의 risk가 높거나 엄격한 심사(Audit)가 요구되는 경우 3.2 증명서가 주로 사용됩니다.

Q: PMI/XRF(성분분석기)로 D2 또는 M2 공구강을 정확하게 검증할 수 있나요?

A: PMI/XRF는 합금 계열 및 다양한 합금 원소를 확인하는 데 유용하지만, 탄소(C) 측정에는 한계가 있습니다. 입고 승인이 탄소 함량에 민감한 특성(경도 반응성, 내마모성)에 의존하는 경우, 자체 SOP에 따라 발광분석(Spark-OES) 또는 ICP-OES를 사용하십시오.

Q: 스틸 스트립 코일 검사 시 로크웰 경도 시험 포인트는 몇 군데가 필요한가요?

A: 폭 및 길이 방향의 경도 변화를 모두 감지할 수 있는 경도 맵을 활용하십시오. 코일 길이 방향(상/중/하) 및 폭 방향(양 끝/중앙/양 끝)을 조합합니다. 이는 경도 균일성을 평가하기 위한 실무적인 최소 9점 측정 기준이 됩니다. 만약 기존 공정 이력상 국소적인 경도 편차가 발생하는 경우 검사 포인트를 추가하십시오.

Q: 스트립 나이프에서 양 끝(Edge)에서 중앙(Center)으로 갈수록 경도 편차가 발생하는 원인은 무엇인가요?

A: 주요 원인으로는 표면 상태의 차이, 양 끝단 근처의 탈탄(Decarburization) 현상, 그리고 가공/열처리 공정의 불균일성이 있습니다. 전형적인 증상은 "양 끝단은 경도가 낮고, 중앙은 정상"으로 나타납니다. 이러한 패턴이 확인되면 탈탄 검사를 추가하고 샘플링 위치 문서화 관리를 강화하십시오.

Q: 공구강 QA(품질보증)에서 ASTM E1077은 어떤 용도로 사용되나요?

A: ASTM E1077은 스틸 시편의 탈탄 깊이(Depth of Decarburization)를 측정하고 평가하는 데 사용됩니다. 실무적으로 표면의 경도 부족(연화)이 나이프 성능에 영향을 미칠 때 입고 승인 여부 결정 및 근본 원인(Root-Cause) 분석을 지원하며, 특히 표면 영역의 상태가 중요한 얇은 스트립 제품에서 더욱 유효합니다.

Q: MTC 화학 성분은 합격인데 경도 시험에서 불합격이 발생하면 어떻게 해야 하나요?

A: 해당 로트(Lot)를 즉시 보관/격리(Hold)하고, 먼저 시험의 유효성(스케일 및 두께 적합성, 지지대, 압흔 간격, 시편 전처리)을 검증하십시오. 시험이 유효하다면 부적합(Nonconformance)으로 처리합니다. 이력(Chain-of-Custody)을 문서화하여 재샘플링을 실시하고, PO/사양서 요구사항과 비교한 후 로트의 최종 처분(제한적 승인, 용도 하향 조정/다운그레이드, 반품/부적합 판정)을 결정하십시오.

Q: 슬리팅(Slitting) 또는 연삭/연마(Grinding) 가공 후에 재검증이 필요한가요?

A: 예, 해당 공정으로 인해 추적성 체인(로트 분할)이 변경되거나 작업 표면(가공면)이 변형된 경우 재검증이 필요합니다. 리스크 평가에 따라 최소한의 추적성(Heat 번호와 내부 로트 간 연동)과 경도/표면 상태를 재검증하십시오. 특히 연삭 가공이나 열처리 후에는 필수적으로 수행해야 합니다.

결론

A clean checklist is only valuable if it reduces real waste: fewer retests, fewer surprises on the grinder, and fewer unplanned stops in production. The acceptance path covered in this guide comes down to four linked checks: confirm the EN 10204 3.1 certificate is correctly issued and signed; verify chemistry against PO/spec with the right method (PMI for screening, OES/ICP for carbon-critical decisions); map hardness at head/mid/tail × edge/center/edge and interpret the spread, not just the average; and verify decarburization depth when the application is edge-sensitive.

Traceability is what ties these checks together. If you can connect the MTC heat number to the coil tag, to your receiving log, and through to internal lot numbers after slitting or grinding—you have a defensible QA record. If any link in that chain is missing, you have paperwork, not traceability. Re-verify hardness and surface condition after any secondary process (slitting, grinding, heat treatment) that changes the working surface or splits the lot identity.

Consistent results require consistent identity. That’s the same internal discipline we apply at Maxtor Metal when aligning documentation and verification steps between supplier and buyer.

Author Bio

제시 쉬
Senior Quality Engineer | Maxtor Metal (QA Department)

Jesse Xu is a Senior Quality Engineer at Maxtor Metal with over 15 years of hands-on experience in tool steel metallurgical quality assurance, material inspection, and failure analysis. Specializing in diagnosing complex blade performance issues—such as distinguishing heat treatment defects from material segregation in chipping and premature wear—he helps global equipment manufacturers ensure total quality from raw material receiving to finished precision cutting tools. Jesse holds prestigious industry credentials, including ASQ CQE (Certified Quality Engineer), ISO 9001 선임 심사원, 그리고 ASNT 레벨 II certifications.