{"id":5711,"date":"2025-12-24T01:49:43","date_gmt":"2025-12-24T01:49:43","guid":{"rendered":"https:\/\/korea-transmission.com\/?p=5711"},"modified":"2025-12-24T01:50:38","modified_gmt":"2025-12-24T01:50:38","slug":"gb-t-3098-7-2000-self-tapping-screw-fastener-properties","status":"publish","type":"post","link":"https:\/\/korea-transmission.com\/pl\/blog\/gb-t-3098-7-2000-self-tapping-screw-fastener-properties\/","title":{"rendered":"GB\/T 3098.7-2000: Self-Tapping Screw Fastener Properties"},"content":{"rendered":"<div style=\"margin-bottom: 30px;\">\n<h2 style=\"color: #333; font-size: 1.5em; border-bottom: 2px solid #ddd; padding-bottom: 10px;\">Zarys artyku\u0142u<\/h2>\n<p style=\"margin-bottom: 15px;\">This article provides a structured overview of the GB\/T 3098.7-2000 standard, optimized for clarity and practical application in mechanical engineering. The outline ensures comprehensive coverage of key aspects:<\/p>\n<ul style=\"list-style-type: disc; padding-left: 20px; margin-bottom: 20px;\">\n<li>Introduction: Scope and significance of the standard.<\/li>\n<li>Materials: Chemical composition and manufacturing guidelines.<\/li>\n<li>Mechanical and Performance Properties: Detailed requirements including hardness, torque, and more.<\/li>\n<li>Test Methods: Procedures for verifying compliance.<\/li>\n<li>Torque Wrenches: Specifications for testing equipment.<\/li>\n<li>Marking: Identification and labeling requirements.<\/li>\n<li>FAQ: Common questions and expert insights.<\/li>\n<\/ul>\n<\/div>\n<div style=\"margin-bottom: 30px;\">\n<h2 style=\"color: #333; font-size: 1.5em; border-bottom: 2px solid #ddd; padding-bottom: 10px;\">Introduction to GB\/T 3098.7-2000 Standard<\/h2>\n<p style=\"margin-bottom: 15px;\">The GB\/T 3098.7-2000 standard specifies the mechanical properties of self-tapping screws used in fasteners. It applies to screws manufactured from case-hardening steel, ensuring reliability in applications requiring high performance under mechanical stress. This standard is essential for industries such as automotive, construction, and machinery, where self-tapping screws provide secure fastening without pre-drilled threads.<\/p>\n<p style=\"margin-bottom: 15px;\">Key benefits include standardized testing for durability, resistance to failure, and compatibility with various materials. Adhering to this standard minimizes risks like hydrogen embrittlement and ensures consistent quality in production. For optimal use, engineers should integrate these specifications into design and quality control processes.<\/p>\n<\/div>\n<div style=\"margin-bottom: 30px;\">\n<h2 style=\"color: #333; font-size: 1.5em; border-bottom: 2px solid #ddd; padding-bottom: 10px;\">Przybory<\/h2>\n<p style=\"margin-bottom: 15px;\">Self-tapping screws shall be manufactured by cold heading from case-hardening steel. The chemical composition provided in Table 1 is for guidance only, allowing flexibility while maintaining core properties. If boron content is controlled by adding titanium and\/or aluminum to render it ineffective, the boron may reach up to 0.005%.<\/p>\n<p style=\"margin-bottom: 15px;\">Guidance on material selection:<\/p>\n<ul style=\"list-style-type: disc; padding-left: 20px; margin-bottom: 20px;\">\n<li>Ensure steel meets carbon and manganese limits to achieve desired hardenability.<\/li>\n<li>Avoid impurities that could compromise case hardening.<\/li>\n<li>Verify composition through ladle and check analyses for batch consistency.<\/li>\n<\/ul>\n<div class=\"table-container\" style=\"overflow-x: auto; margin-bottom: 20px;\">\n<h3 style=\"text-align: center; font-size: 1.2em; margin-bottom: 10px;\">Table 1: Chemical Composition<\/h3>\n<table style=\"border-collapse: collapse; width: 100%; margin-bottom: 20px;\">\n<thead>\n<tr style=\"background-color: #f2f2f2;\">\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\" rowspan=\"2\">Analysis<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\" colspan=\"2\">Composition Limits, %<\/th>\n<\/tr>\n<tr style=\"background-color: #f2f2f2;\">\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Carbon<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Manganese<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Ladle<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.15~0.25<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.70~1.65<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Check<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.13~0.27<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.64~1.71<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<div style=\"margin-bottom: 30px;\">\n<h2 style=\"color: #333; font-size: 1.5em; border-bottom: 2px solid #ddd; padding-bottom: 10px;\">Mechanical and Performance Properties<\/h2>\n<p style=\"margin-bottom: 15px;\">The standard outlines mechanical and performance requirements, with test methods referenced in Table 2. Screws must undergo case hardening and tempering at a minimum temperature of 340\u00b0C to meet these criteria.<\/p>\n<div class=\"table-container\" style=\"overflow-x: auto; margin-bottom: 20px;\">\n<h3 style=\"text-align: center; font-size: 1.2em; margin-bottom: 10px;\">Table 2: Mechanical and Performance Properties Items<\/h3>\n<table style=\"border-collapse: collapse; width: 100%; margin-bottom: 20px;\">\n<thead>\n<tr style=\"background-color: #f2f2f2;\">\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Property Item<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Technical Requirement (Clause or Table)<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Test Method (Clause)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Core Hardness<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4.3<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5.1<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Surface Hardness<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4.3<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5.2<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Case Depth<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4.4, Table 4<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5.3<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Torsional Strength<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4.5, Table 3<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5.4<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Head Soundness<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4.6<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5.5<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Drive Test<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4.7, Table 3<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5.6<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Hydrogen Embrittlement<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4.8<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5.7<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Core Hardness After Retempering<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4.9<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5.8<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Tensile Strength<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4.10, Table 3<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5.9<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Obr\u00f3bka cieplna<\/h3>\n<p style=\"margin-bottom: 15px;\">Finished screws require case hardening and tempering at no less than 340\u00b0C, complying with all properties in Table 3. This process enhances surface hardness while maintaining core toughness, crucial for torque resistance.<\/p>\n<div class=\"table-container\" style=\"overflow-x: auto; margin-bottom: 20px;\">\n<h3 style=\"text-align: center; font-size: 1.2em; margin-bottom: 10px;\">Table 3: Mechanical and Performance Requirements<\/h3>\n<table style=\"border-collapse: collapse; width: 100%; margin-bottom: 20px;\">\n<thead>\n<tr style=\"background-color: #f2f2f2;\">\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Nominal Thread Diameter (mm)<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Minimum Torsional Strength (N\u00b7m)<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Maximum Drive Torque (N\u00b7m)<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Minimum Tensile Strength (Reference) (N)<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.3<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">1940<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2.5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">1.2<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.6<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3150<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2.1<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">1.1<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4680<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3.5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3.4<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">1.7<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">6300<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4.9<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2.5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">8170<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">10<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">13200<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">6<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">17<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">8.5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">18700<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">8<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">42<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">21<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">34000<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">10<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">85<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">43<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">53900<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">12<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">150<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">75<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">78400<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Hardness<\/h3>\n<p style=\"margin-bottom: 15px;\">Core hardness shall be 290~370 HV10, with minimum surface hardness of 450 HV0.3. These values ensure balance between ductility and wear resistance, vital for self-tapping applications.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Case Depth<\/h3>\n<p style=\"margin-bottom: 15px;\">Case depth must comply with Table 4, providing sufficient hardened layer for torque and wear performance without excessive brittleness.<\/p>\n<div class=\"table-container\" style=\"overflow-x: auto; margin-bottom: 20px;\">\n<h3 style=\"text-align: center; font-size: 1.2em; margin-bottom: 10px;\">Table 4: Case Depth<\/h3>\n<table style=\"border-collapse: collapse; width: 100%; margin-bottom: 20px;\">\n<thead>\n<tr style=\"background-color: #f2f2f2;\">\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\" rowspan=\"2\">Nominal Thread Diameter (mm)<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\" colspan=\"2\">Case Depth (mm)<\/th>\n<\/tr>\n<tr style=\"background-color: #f2f2f2;\">\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Min<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Max<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2, 2.5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.04<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.12<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3, 3.5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.05<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.18<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4, 5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.1<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.25<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">6, 8<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.15<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.28<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">10, 12<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.15<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">0.32<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Torsional Strength<\/h3>\n<p style=\"margin-bottom: 15px;\">Torsional strength per Table 3; failure must not occur in clamped threads. This test simulates real-world installation stresses.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Head Soundness<\/h3>\n<p style=\"margin-bottom: 15px;\">No cracks at head-shank junction when support face deforms to 7\u00b0 angle. Test qualifies even if failure occurs at first thread, provided head remains intact.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Thread Forming Ability<\/h3>\n<p style=\"margin-bottom: 15px;\">Screws must form mating internal threads without permanent deformation, with drive torque not exceeding Table 3 values. Formed threads shall accept GB\/T 197 6h tolerance external threads and sustain grade 8 loads per GB\/T 3098.2.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Hydrogen Embrittlement Resistance<\/h3>\n<p style=\"margin-bottom: 15px;\">Electroplated screws require process review per GB\/T 3098.17 to control hydrogen embrittlement. Post-plating, perform hydrogen expulsion per GB\/T 5267. Non-electrolytic zinc flake coatings per ISO 10683 are recommended.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Core Hardness After Retempering<\/h3>\n<p style=\"margin-bottom: 15px;\">Hardness drop after retempering shall not exceed 20 HV, ensuring stability in service.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Tensile Strength<\/h3>\n<p style=\"margin-bottom: 15px;\">For screws \u226512 mm or \u22653d, tensile test by agreement; reference values in Table 3 guide expected performance.<\/p>\n<\/div>\n<div style=\"margin-bottom: 30px;\">\n<h2 style=\"color: #333; font-size: 1.5em; border-bottom: 2px solid #ddd; padding-bottom: 10px;\">Test Methods<\/h2>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Core Hardness Test<\/h3>\n<p style=\"margin-bottom: 15px;\">Measure at half-radius on cross-section away from end, through minor diameter, per GB\/T 4340.1. This verifies internal toughness.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Surface Hardness Test<\/h3>\n<p style=\"margin-bottom: 15px;\">Routine: At end, shank, or head per GB\/T 4340.1 after coating removal. Arbitration: Vickers microhardness HV0.1 on profile \u22654 mm diameter, \u22650.05 mm from edge; negotiate for &lt;4 mm.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Case Depth Test<\/h3>\n<p style=\"margin-bottom: 15px;\">Distancefrom surface to point where hardness = core +30 HV0.3; arbitration uses HV0.3 microhardness on prepared metallographic sample.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Torsional Strength Test<\/h3>\n<p style=\"margin-bottom: 15px;\">Clamp specimen with \u22652 full threads in fixture, \u22652 exposed; apply torque until failure, record value per Table 3.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Head Soundness Test<\/h3>\n<p style=\"margin-bottom: 15px;\">Insert into wedge with hole diameter = nominal +0.05 mm (\u2264M6) or +0.1 mm (&gt;M6~M12); apply axial load to 7\u00b0 deformation. Not for countersunk heads. Use hammer strikes if needed.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Drive Test<\/h3>\n<p style=\"margin-bottom: 15px;\">Drive into test plate (low-carbon steel, 140~180 HV30, thickness = nominal diameter, hole per Table 5) until \u22651 thread protrudes. Initial axial force \u226450 N (\u2264M5) or \u2264100 N (&gt;M5); speed \u226430 r\/min for arbitration. Add lubricant if needed.<\/p>\n<div class=\"table-container\" style=\"overflow-x: auto; margin-bottom: 20px;\">\n<h3 style=\"text-align: center; font-size: 1.2em; margin-bottom: 10px;\">Table 5: Test Plate Thickness and Hole Diameters<\/h3>\n<table style=\"border-collapse: collapse; width: 100%; margin-bottom: 20px;\">\n<thead>\n<tr style=\"background-color: #f2f2f2;\">\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\" colspan=\"2\">Nominal Thread Diameter (mm)<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2.5<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3.5<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">6<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">8<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">10<\/th>\n<th style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">12<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\" colspan=\"2\">Thickness (mm)<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2.5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3.5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">6<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">8<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">10<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">12<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\" rowspan=\"2\">Hole Diameter (mm)<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Max<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">1.825<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2.275<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2.775<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3.18<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3.68<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4.53<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5.43<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">7.336<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">9.236<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">11.143<\/td>\n<\/tr>\n<tr>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">Min<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">1.8<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2.25<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">2.75<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3.15<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">3.65<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">4.5<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">5.4<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">7.3<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">9.2<\/td>\n<td style=\"border: 1px solid #ddd; padding: 8px; text-align: left;\">11.1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<p style=\"margin-bottom: 15px;\">Note: Test plate thickness tolerance per GB\/T 709 for rolled steel plates.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Hydrogen Embrittlement Test<\/h3>\n<p style=\"margin-bottom: 15px;\">Per GB\/T 3098.17, using parallel support method to assess process control.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Retempering Test<\/h3>\n<p style=\"margin-bottom: 15px;\">At 330\u00b0C for 1h; average of three core hardness points differs by \u226420 HV pre\/post. For arbitration only.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Tensile Test<\/h3>\n<p style=\"margin-bottom: 15px;\">Clamp with \u22656 threads exposed; apply axial load \u226425 mm\/min until failure. Failure in shank or threads, not head junction; self-centering grips required.<\/p>\n<\/div>\n<div style=\"margin-bottom: 30px;\">\n<h2 style=\"color: #333; font-size: 1.5em; border-bottom: 2px solid #ddd; padding-bottom: 10px;\">Torque Wrenches<\/h2>\n<p style=\"margin-bottom: 15px;\">For torsional and drive tests, error \u2264\u00b13% of specified torque. Equivalent powered devices allowed; manual for arbitration. Calibration ensures accurate assessment of screw performance under load.<\/p>\n<\/div>\n<div style=\"margin-bottom: 30px;\">\n<h2 style=\"color: #333; font-size: 1.5em; border-bottom: 2px solid #ddd; padding-bottom: 10px;\">Marking<\/h2>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Marking Code<\/h3>\n<p style=\"margin-bottom: 15px;\">Case-hardened and tempered self-tapping screws marked with \u201c-O-\u201d.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Identification<\/h3>\n<p style=\"margin-bottom: 15px;\">Indented or raised marking required for \u22655 mm nominal diameter hex or hexalobular heads, preferably on head. By agreement for other types.<\/p>\n<h3 style=\"font-size: 1.2em; margin-top: 20px; margin-bottom: 10px;\">Manufacturer’s Identification Mark<\/h3>\n<p style=\"margin-bottom: 15px;\">Mandatory for all marked products, ensuring traceability and quality assurance.<\/p>\n<\/div>\n<div style=\"margin-bottom: 30px;\">\n<h2 style=\"color: #333; font-size: 1.5em; border-bottom: 2px solid #ddd; padding-bottom: 10px;\">Cz\u0119sto zadawane pytania<\/h2>\n<ol style=\"list-style-type: decimal; padding-left: 20px; margin-bottom: 20px;\">\n<li style=\"margin-bottom: 15px;\"><strong>What is the purpose of case hardening in self-tapping screws?<\/strong><br \/>\nCase hardening provides a hard surface for thread forming and wear resistance while keeping the core ductile to prevent brittle failure under torque or tension, as specified in clauses 4.2 and 4.3.<\/li>\n<li style=\"margin-bottom: 15px;\"><strong>How can hydrogen embrittlement be mitigated in electroplated screws?<\/strong><br \/>\nImplement process controls per GB\/T 3098.17, perform post-plating hydrogen expulsion per GB\/T 5267, and consider non-electrolytic coatings like zinc flake per ISO 10683 to reduce risk.<\/li>\n<li style=\"margin-bottom: 15px;\"><strong>What if a screw fails the torsional strength test in the clamped area?<\/strong><br \/>\nFailure in the clamped threads invalidates the test; ensure proper fixturing with at least two full threads clamped and exposed, as per 5.4, to accurately assess material strength.<\/li>\n<li style=\"margin-bottom: 15px;\"><strong>Are tensile tests mandatory for all self-tapping screws?<\/strong><br \/>\nNo, only for lengths \u226512 mm or \u22653d by supplier-buyer agreement; Table 3 values are references, emphasizing torsional and drive properties as primary metrics.<\/li>\n<li style=\"margin-bottom: 15px;\"><strong>How does case depth affect screw performance?<\/strong><br \/>\nInsufficient depth may lead to premature wear or failure in thread forming, while excessive depth increases brittleness; adhere to Table 4 limits for balanced properties in applications like steel assemblies.<\/li>\n<li style=\"margin-bottom: 15px;\"><strong>What equipment is recommended for arbitration tests?<\/strong><br \/>\nUse manual torque wrenches with \u00b13% accuracy for torsional and drive tests, and Vickers microhardness for surface and case depth arbitration to ensure unbiased, precise results.<\/li>\n<\/ol>\n<\/div>\n<p>&nbsp;<\/p>","protected":false},"excerpt":{"rendered":"<p>Article Outline This article provides a structured overview of the GB\/T 3098.7-2000 standard, optimized for clarity and practical application in mechanical engineering. The outline ensures comprehensive coverage of key aspects: Introduction: Scope and significance of the standard. Materials: Chemical composition and manufacturing guidelines. Mechanical and Performance Properties: Detailed requirements including hardness, torque, and more. Test [&hellip;]<\/p>","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_et_pb_use_builder":"","_et_pb_old_content":"","_et_gb_content_width":"","footnotes":""},"categories":[220],"tags":[],"class_list":["post-5711","post","type-post","status-publish","format-standard","hentry","category-technical-documentation-and-references"],"_links":{"self":[{"href":"https:\/\/korea-transmission.com\/pl\/wp-json\/wp\/v2\/posts\/5711","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/korea-transmission.com\/pl\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/korea-transmission.com\/pl\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/korea-transmission.com\/pl\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/korea-transmission.com\/pl\/wp-json\/wp\/v2\/comments?post=5711"}],"version-history":[{"count":2,"href":"https:\/\/korea-transmission.com\/pl\/wp-json\/wp\/v2\/posts\/5711\/revisions"}],"predecessor-version":[{"id":5713,"href":"https:\/\/korea-transmission.com\/pl\/wp-json\/wp\/v2\/posts\/5711\/revisions\/5713"}],"wp:attachment":[{"href":"https:\/\/korea-transmission.com\/pl\/wp-json\/wp\/v2\/media?parent=5711"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/korea-transmission.com\/pl\/wp-json\/wp\/v2\/categories?post=5711"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/korea-transmission.com\/pl\/wp-json\/wp\/v2\/tags?post=5711"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}