# Metals Lab Handbook > An independent guide to physical and chemical metallurgical testing Metals Lab Handbook is an independent editorial site publishing practical, evergreen explainers on metallurgical and mechanical testing explained. ## Articles - [How are engine stands and lifting gear proof tested?](https://trinitymetalslaboratory.com/blog/engine-stand-proof-load-testing): How proof load tests, periodic inspections, and NDT are applied to lifting devices, and how to evaluate a rented aircraft engine stand like the Trent 700 unit. Load factors, intervals, and documentation explained. - [Metals Testing Glossary: Key Terms and Acronyms](https://trinitymetalslaboratory.com/blog/metals-testing-glossary): A glossary of 40+ essential metals testing terms and acronyms (UTS, yield strength, elongation, Charpy, HBW, HRC, HV, HK, proof load, macro etch, grain size, OES, MTR) with applicable ASTM standards for quality and welding engineers. - [Optical Emission Spectroscopy (OES) for Metal Analysis](https://trinitymetalslaboratory.com/blog/optical-emission-spectroscopy-oes): How spark optical emission spectroscopy (OES) delivers rapid quantitative elemental analysis of metals. Covers sample prep, burn placement, standardization and limitations for carbon and sulfur. - [Measuring Decarburization and Carburization Depth in Steel](https://trinitymetalslaboratory.com/blog/decarburization-measurement-guide): Measuring decarburization depth in steel per ASTM E1077: types, microhardness and metallographic methods, sample prep pitfalls, and AMS/ASTM acceptance specs. - [Grain Size Measurement: ASTM E112 Comparison and Planimetric Methods](https://trinitymetalslaboratory.com/blog/grain-size-measurement-methods): Practical comparison of ASTM E112 comparison, planimetric and intercept methods for grain size measurement, with a selection table and Hall-Petch guidance. - [Macro Etching for Weld Inspection: Procedure and Interpretation](https://trinitymetalslaboratory.com/blog/macro-etch-weld-inspection): Macro etching reveals weld macrostructures for quality assessment. This guide covers procedure, interpretation of fusion zone, HAZ, and defects per ASTM E340. - [Weld Procedure and Welder Qualification: Test Checklist](https://trinitymetalslaboratory.com/blog/weld-qualification-testing-checklist): Checklist for AWS D1.1 and ASME IX weld qualification tests: tensile, bend, Charpy, macro etch, hardness. Includes specimen dimensions, quantity and ID. - [Fastener Testing: Proof Load, Wedge Tensile and Hydrogen Embrittlement](https://trinitymetalslaboratory.com/blog/fastener-proof-load-wedge-tensile): Proof load, wedge tensile, and hydrogen embrittlement testing for fasteners per ASTM F606, SAE J429, ASTM A193, and ISO 898-1. Learn procedures, rationale, and acceptance criteria. - [Bend Testing vs Tensile Elongation for Ductility](https://trinitymetalslaboratory.com/blog/bend-test-vs-tensile-ductility): Bend test vs tensile elongation: why materials may pass elongation but crack in bending. Explains effects of surface condition, strain rate, anisotropy. - [Charpy V-Notch Impact Testing: A Practical Explainer](https://trinitymetalslaboratory.com/blog/charpy-impact-test-explained): Charpy V-notch impact testing per ASTM E23 measures toughness via absorbed energy, lateral expansion and shear fracture; covers transition curves and sub-size specimen effects. - [Microhardness Testing for Case Depth and Coatings](https://trinitymetalslaboratory.com/blog/microhardness-testing-case-depth): Microhardness testing per ASTM E384 for case depth, decarburization and coatings. Covers Vickers and Knoop traverse testing, load selection, spacing rules and depth-vs-hardness plots per AMS/SAE specs. - [Hardness Conversion Charts: Why They Are Not Universal](https://trinitymetalslaboratory.com/blog/hardness-conversion-caveats): ASTM E140 hardness conversions are empirical correlations valid only for specific alloy families. Learn why converting across steel, aluminum, and copper groups introduces significant error and when direct testing is mandatory. - [Rockwell vs Brinell vs Vickers: Hardness Test Comparison](https://trinitymetalslaboratory.com/blog/rockwell-vs-brinell-vs-vickers): Practical comparison of Rockwell, Brinell, and Vickers hardness tests: indenter types, loads, ASTM standards, applications, and how to choose the right method for QA, welding, and procurement. - [How to Read a Tensile Test Report (Step by Step)](https://trinitymetalslaboratory.com/blog/how-to-read-tensile-test-report): A step-by-step guide to reading ASTM E8 tensile test reports. Learn what yield strength, UTS, elongation and reduction of area reveal about a metal, common unit mix-ups and red flags that suggest a bad test. - [Engineering Stress vs True Stress: When to Use Each](https://trinitymetalslaboratory.com/blog/engineering-vs-true-stress-strain): Engineering stress vs true stress explained with formulas, necking correction and a side-by-side comparison table. Covers when to use each for FEA, forming simulations and ASTM E8/E646 compliance. - [Mechanical Testing of Metals: The Complete Guide](https://trinitymetalslaboratory.com/blog/mechanical-testing-guide): Mechanical testing of metals: tensile, hardness, impact, bend and fastener tests organized by strength, ductility and toughness. Includes decision flowchart for test selection. ## More - [Full LLM text](/llms-full.txt) - [Glossary](/glossary)