CN Quality Check
Standards Comparison Tool
EXECUTIVE SUMMARY
The query "GB235B" is not a valid Chinese standard designation. Both independent drafts converge on the same interpretation: the user most likely intends Q235B carbon structural steel per GB/T 700-2006 (碳素结构钢 / Carbon Structural Steel). A secondary candidate is GB/T 235-2013 (金属材料 薄板和薄带 反复弯曲试验方法 / Metallic materials — Sheets and strips — Reverse bend test), but the "B" suffix is invalid there. Overall equivalence landscape: Q235B is broadly comparable to EN S235 and ASTM A36 but not identical — impact energy and deoxidation requirements differ. Procurement implication: confirm the intended grade in writing before ordering; do not accept "GB235B" on any mill certificate.
APPLICABLE CHINESE STANDARDS
| Standard No. | Title (Chinese) | Scope | Mandatory/Recommended | Status |
|---|---|---|---|---|
| GB/T 700-2006 | 碳素结构钢 (Carbon structural steel) | Q195–Q275 grades incl. Q235B | Recommended (GB/T) | Current |
| GB/T 235-2013 | 金属材料 薄板和薄带 反复弯曲试验方法 (Metallic materials — Sheets and strips — Reverse bend test) | Test method only | Recommended (GB/T) | Current |
| GB/Z 235-2026 | 人工智能 科学计算 共性算子 (AI — Scientific computing — Common operators) | Unrelated to steel | Guiding (GB/Z) | Current |
| GB/T 23561.1-2024 | 煤和岩石物理力学性质测定方法 第1部分：采样一般规定 (Methods for determining physical and mechanical properties of coal and rock — Part 1: Sampling) | Unrelated to steel | Recommended (GB/T) | Current |
| GB 50205-2020 | 钢结构工程施工质量验收标准 (Standard for acceptance of construction quality of steel structures) | Installation/acceptance | Mandatory (GB) | Current |
STANDARD TIER CLASSIFICATION
| Standard | Tier | Description |
|---|---|---|
| GB/T 700-2006 | TIER 1 — Product Standard | Defines composition, mechanical properties, delivery condition |
| GB/T 235-2013 | TIER 2 — Test Method | Reverse bend test procedure |
| GB 50205-2020 | TIER 3 — Installation/Acceptance Code | On-site steel structure verification |
| EN 10025-2:2019 | TIER 1 — Product Standard | Non-alloy structural steels |
| ASTM A36/A36M-19 | TIER 1 — Product Standard | Carbon structural steel |
FLAG: GB/T 235-2013 is a TIER 2 test method — it cannot substitute for a product specification. If the user intended GB/T 235, no product comparison is possible.
SCOPE BREAKDOWN
Q235B Carbon Structural Steel (primary interpretation)
Chinese standard: GB/T 700-2006: 碳素结构钢 (Carbon structural steel)
International equivalent: EN 10025-2:2019 S235JR — ⚠️ edition 2019; ASTM A36/A36M-19
Equivalence: MOD (modified — similar but not identical)
Standard tier match: Both TIER 1 — valid comparison
| Parameter | Chinese Standard Value (Clause) | International Value (Clause) | Deviation | Mutual Recognition | Procurement Impact |
|---|---|---|---|---|---|
| Yield strength ReH | ≥235 MPa (GB/T 700-2006 §6, Q235, thickness ≤16 mm) | S235JR ≥235 MPa (EN 10025-2:2019 Table 3, ≤16 mm); A36 ≥250 MPa (ASTM A36/A36M-19 Table 2) | Identical vs EN; −6% vs A36 | 直接互认 (Direct mutual recognition) vs EN; 附加测试后互认 (Mutual recognition after additional testing) vs A36 | LOW |
| Tensile strength Rm | 370–500 MPa (GB/T 700-2006 §6) | S235JR 360–510 MPa (EN 10025-2:2019 Table 3); A36 400–550 MPa (ASTM A36/A36M-19 Table 2) | Different band; CN narrower | 附加测试后互认 (Mutual recognition after additional testing) | MEDIUM |
| Elongation A | ≥26% (GB/T 700-2006 §6, gauge length 5.65√S₀) | S235JR ≥26% (EN 10025-2:2019 Table 3); A36 ≥20% (ASTM A36/A36M-19 Table 2, 200 mm gauge) | Identical vs EN; gauge length differs vs ASTM | 附加测试后互认 (Mutual recognition after additional testing) | MEDIUM |
| Impact energy (Charpy V) | +20°C ≥27 J (GB/T 700-2006 §6, Q235B) | S235JR +20°C ≥27 J (EN 10025-2:2019 Table 5); A36 not mandatory (ASTM A36/A36M-19 §5) | Identical vs EN; A36 silent | 直接互认 (Direct mutual recognition) vs EN; 不可互认 (Not mutually recognised) vs A36 | HIGH |
| Carbon content | ≤0.20% (GB/T 700-2006 Table 1, Q235) | S235JR ≤0.17% (EN 10025-2:2019 Table 1); A36 ≤0.26% (ASTM A36/A36M-19 Table 1) | +18% vs EN; −23% vs A36 | 附加测试后互认 (Mutual recognition after additional testing) | MEDIUM |
| Deoxidation | Q235B: 镇静钢 (killed steel) required (GB/T 700-2006 §5) | S235JR: fully killed (EN 10025-2:2019 §5.2) | Identical intent | 直接互认 (Direct mutual recognition) | LOW |
GB/T 235-2013 Reverse Bend Test (secondary interpretation)
Chinese standard: GB/T 235-2013: 金属材料 薄板和薄带 反复弯曲试验方法 (Metallic materials — Sheets and strips — Reverse bend test)
International equivalent: ISO 7799:1985 — ⚠️ edition 1985
Equivalence: NEQ (test method only — no product parameters)
Standard tier match: Both TIER 2 — valid comparison
Note: No product parameter table applicable. This standard defines test procedure only; it cannot be used as a procurement specification.
KEY DIFFERENCES SUMMARY
- Designation validity — "GB235B" is invalid; correct designation is Q235B under GB/T 700-2006. Impact: HIGH (documentation rejection risk).
- Carbon content — Q235B ≤0.20% vs S235JR ≤0.17% (+18%). 附加测试后互认 (Mutual recognition after additional testing). Impact: MEDIUM.
- Impact energy — Q235B +20°C ≥27 J matches S235JR; ASTM A36 has no mandatory Charpy requirement. 不可互认 (Not mutually recognised) vs A36. Impact: HIGH.
- Tensile band — CN 370–500 MPa vs EN 360–510 MPa vs ASTM 400–550 MPa. 附加测试后互认 (Mutual recognition after additional testing). Impact: MEDIUM.
- Elongation gauge length — CN/EN use 5.65√S₀; ASTM uses 200 mm. Values not directly comparable. 附加测试后互认 (Mutual recognition after additional testing). Impact: MEDIUM.
REGULATORY LINKAGE TABLE (法规联动)
| Compliance Scenario | Chinese Regulatory Basis | International Regulatory Basis |
|---|---|---|
| Mandatory product certification | Not applicable — GB/T 700-2006 is voluntary; mill certificate (质保书 / Mill Test Certificate) per GB/T 700-2006 §7 | EN 10204 3.1 inspection certificate (EN 10025-2:2019 §9); ASTM A6/A6M |
| Engineering acceptance inspection | GB 50205-2020 钢结构工程施工质量验收标准 (Standard for acceptance of construction quality of steel structures) | Local building code / Eurocode 3 (EN 1993) |
| Import/export compliance | CCIB commodity inspection; GB/T 700-2006 §7 marking | Destination customs; CE marking (EN 10025-2 CPR) |
| Designer/engineer obligation | GB 50017-2017 钢结构设计标准 (Standard for design of steel structures) | Eurocode 3 / AISC 360 |
AUDIT FLAG RESOLUTION
- 🔴 CRITICAL CORRECTION: "GB235B" is not a standard number. Correct designation: Q235B grade under GB/T 700-2006. Both drafts A and B independently reached this conclusion.
- ✅ RESOLVED: GB/T 235-2013 confirmed CURRENT (现行) per official authority — no supersession note added.
- ✅ RESOLVED: GB/Z 235-2026 and GB/T 23561.1-2024 confirmed CURRENT — both unrelated to steel procurement; listed for completeness only.
- ✅ FALSE POSITIVE (domain flag): GB/T 235-2013 — flagged as possible user intent, but "B" suffix is invalid; usage as test method is valid within TIER 2 only.
- ⚠️ UNRESOLVED: Exact Q235B impact energy clause number — verify against GB/T 700-2006 §6 Table 3.
PROCUREMENT VERDICT
- Obtain written confirmation from the buyer that the intended grade is Q235B per GB/T 700-2006.
- Reject any mill certificate bearing "GB235B" — invalid designation.
- Specify impact energy test temperature (+20°C) and Charpy value (≥27 J) explicitly in the PO.
- If substituting EN S235JR, require EN 10204 3.1 certificate and confirm carbon ≤0.17%.
- If substituting ASTM A36, add a supplementary Charpy requirement — A36 alone does not guarantee impact toughness.
- Confirm deoxidation method (镇静钢 / killed steel) on the certificate.
REFERENCE DOCUMENT CHECKLIST (配套调阅清单)
- GB/T 700-2006 §6 Table 3 — Q235B mechanical properties (ReH, Rm, A, impact energy)
- GB/T 700-2006 Table 1 — chemical composition limits
- GB/T 700-2006 §5 — deoxidation method requirements
- EN 10025-2:2019 Table 3 & Table 5 — S235JR mechanical and impact values
- ASTM A36/A36M-19 Table 1 & Table 2 — composition and tensile requirements
- GB 50205-2020 — acceptance criteria for structural steel on site
FIELD INSPECTION CHECKLIST
- Verify mill certificate grade reads "Q235B" and standard reads "GB/T 700-2006".
- Confirm Charpy impact test report at +20°C with ≥27 J.
- Check carbon content ≤0.20% on chemical analysis.
- Confirm "镇静钢 (killed steel)" noted on certificate.
- Verify steel grade marking (stencil/stamp) on each plate/section matches certificate.
- Cross-check heat number between certificate and physical marking.
CONFIDENCE RATING
🟡 MEDIUM — core interpretation (Q235B / GB/T 700-2006) agreed by both independent drafts; ≤3 parameters (exact clause numbers for impact energy and deoxidation) flagged for official text confirmation.
Technical comparison report — CN Quality Check Standards Tool. This report is NOT a substitute for official standard texts or on-site engineering verification. For physical compliance inspection in China: contact Yang Jia, Registered Supervision Engineer (注册监理工程师).
Need on-site compliance verification in China?
This report is an AI-assisted technical reference. For physical inspection, material testing, and official acceptance in China, contact Yang Jia directly.
Request an Inspection →