{"id":3485,"date":"2026-07-14T16:10:45","date_gmt":"2026-07-14T08:10:45","guid":{"rendered":"https:\/\/jblstainless.com\/?post_type=product&#038;p=3485"},"modified":"2026-07-14T16:13:14","modified_gmt":"2026-07-14T08:13:14","slug":"mild-steel-q345qd-hot-rolled-carbon-square-and-rectangular-tubes-steel-for-bridge-building","status":"publish","type":"product","link":"https:\/\/jblstainless.com\/it\/mild-steel-q345qd-hot-rolled-carbon-square-and-rectangular-tubes-steel-for-bridge-building\/","title":{"rendered":"Mild Steel Q345qd Hot Rolled Carbon Square and rectangular tubes Steel  for Bridge Building"},"content":{"rendered":"<div data-elementor-type=\"product-post\" data-elementor-id=\"3485\" class=\"elementor elementor-3485\" data-elementor-post-type=\"product\">\n\t\t\t\t<div class=\"elementor-element elementor-element-c663435 e-flex e-con-boxed e-con e-parent\" data-id=\"c663435\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-e4d720a elementor-widget elementor-widget-text-editor\" data-id=\"e4d720a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p>&#8220;<span style=\"color: #ff6600;\">JINBAILAI<\/span> company Mild Steel Q345qd Hot Rolled Carbon Square and rectangular tubes Steel for Bridge Building features a core advantage of a <span style=\"color: #ff6600;\">345MPa<\/span> yield strength and <span style=\"color: #ff6600;\">-20\u2103<\/span> impact toughness. Through the use of niobium-vanadium alloy and TMCP technology, it achieves a balance between high strength and low-temperature toughness. It has been successfully applied to super projects such as the Hong Kong-Zhuhai-Macao Bridge, and will lead the 80 billion high-end welded pipe market in the future.&#8221;<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-775f345 elementor-align-center elementor-widget elementor-widget-button\" data-id=\"775f345\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<div class=\"elementor-button-wrapper\">\n\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-sm\" href=\"https:\/\/jblstainless.com\/it\/contatto\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t<span class=\"elementor-button-icon\">\n\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-baby-carriage\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M144.8 17c-11.3-17.8-37.2-22.8-54-9.4C35.3 51.9 0 118 0 192h256L144.8 17zM496 96h-48c-35.3 0-64 28.7-64 64v64H0c0 50.6 23 96.4 60.3 130.7C25.7 363.6 0 394.7 0 432c0 44.2 35.8 80 80 80s80-35.8 80-80c0-8.9-1.8-17.2-4.4-25.2 21.6 5.9 44.6 9.2 68.4 9.2s46.9-3.3 68.4-9.2c-2.7 8-4.4 16.3-4.4 25.2 0 44.2 35.8 80 80 80s80-35.8 80-80c0-37.3-25.7-68.4-60.3-77.3C425 320.4 448 274.6 448 224v-64h48c8.8 0 16-7.2 16-16v-32c0-8.8-7.2-16-16-16zM80 464c-17.6 0-32-14.4-32-32s14.4-32 32-32 32 14.4 32 32-14.4 32-32 32zm320-32c0 17.6-14.4 32-32 32s-32-14.4-32-32 14.4-32 32-32 32 14.4 32 32z\"><\/path><\/svg>\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Click Here Inquiry Price<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-7e2e566 elementor-widget elementor-widget-spacer\" data-id=\"7e2e566\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"spacer.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"elementor-spacer\">\n\t\t\t<div class=\"elementor-spacer-inner\"><\/div>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-fc7c93d e-flex e-con-boxed e-con e-parent\" data-id=\"fc7c93d\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t<div class=\"elementor-element elementor-element-8e0c482 e-con-full e-flex e-con e-child\" data-id=\"8e0c482\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-2926c1b elementor-widget elementor-widget-image\" data-id=\"2926c1b\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img fetchpriority=\"high\" decoding=\"async\" width=\"700\" height=\"463\" src=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Development-of-Q345qD-Thicker-Bridge-Steel-Plate-of-130mm.png\" class=\"attachment-large size-large wp-image-3492\" alt=\"\" srcset=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Development-of-Q345qD-Thicker-Bridge-Steel-Plate-of-130mm.png 700w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Development-of-Q345qD-Thicker-Bridge-Steel-Plate-of-130mm-18x12.png 18w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Development-of-Q345qD-Thicker-Bridge-Steel-Plate-of-130mm-600x397.png 600w\" sizes=\"(max-width: 700px) 100vw, 700px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-7838dfc e-con-full e-flex e-con e-child\" data-id=\"7838dfc\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-1e5c3fe elementor-widget elementor-widget-text-editor\" data-id=\"1e5c3fe\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p style=\"text-align: center;\"><span style=\"color: #ff6600;\">Delivery form of the interface pipe<\/span><br \/>Square-section pipes can be delivered in the form of interface pipes, but the user needs to remove the interface pipes during use. This form is suitable for scenarios that require on-site connection, such as extremely long structures or projects with restricted transportation.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-c234d16 e-con-full e-flex e-con e-child\" data-id=\"c234d16\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-58bcb14 elementor-widget elementor-widget-image\" data-id=\"58bcb14\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" width=\"700\" height=\"320\" src=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345q-Series-Structural-Steel-for-Bridge.png\" class=\"attachment-large size-large wp-image-3493\" alt=\"\" srcset=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345q-Series-Structural-Steel-for-Bridge.png 700w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345q-Series-Structural-Steel-for-Bridge-18x8.png 18w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345q-Series-Structural-Steel-for-Bridge-600x274.png 600w\" sizes=\"(max-width: 700px) 100vw, 700px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-98c59f2 e-flex e-con-boxed e-con e-parent\" data-id=\"98c59f2\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t<div class=\"elementor-element elementor-element-9debbbf e-con-full e-flex e-con e-child\" data-id=\"9debbbf\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-e8ada7a elementor-widget elementor-widget-image\" data-id=\"e8ada7a\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img decoding=\"async\" width=\"697\" height=\"858\" src=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345-Rectangular-Steel-Pipe-and-Square-Steel-Tube.png\" class=\"attachment-large size-large wp-image-3494\" alt=\"\" srcset=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345-Rectangular-Steel-Pipe-and-Square-Steel-Tube.png 697w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345-Rectangular-Steel-Pipe-and-Square-Steel-Tube-569x700.png 569w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345-Rectangular-Steel-Pipe-and-Square-Steel-Tube-10x12.png 10w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345-Rectangular-Steel-Pipe-and-Square-Steel-Tube-600x739.png 600w\" sizes=\"(max-width: 697px) 100vw, 697px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-b4eb1d6 e-con-full e-flex e-con e-child\" data-id=\"b4eb1d6\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-83157d9 elementor-widget elementor-widget-spacer\" data-id=\"83157d9\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"spacer.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"elementor-spacer\">\n\t\t\t<div class=\"elementor-spacer-inner\"><\/div>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-60177e6 elementor-widget elementor-widget-text-editor\" data-id=\"60177e6\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<h4 style=\"text-align: center;\"><span style=\"color: #ff6600;\">Q345QD Steel Application Area<\/span><\/h4><ul><li>Costruzione navale<\/li><li>Frame structure of large buildings<\/li><li>Factory building Warehouse<\/li><li>Exhibition hall<\/li><li>Power tower<\/li><li>Agricultural greenhouse<\/li><li>Steel structure frame<\/li><li>Temporary building<\/li><li>Manufacturing machinery frame Protective cover<\/li><li>Conveyor equipment support<\/li><li>Light pole<\/li><li>Traffic sign<\/li><li>Advertising board support Bridge<\/li><li>Railings<\/li><li>Truss structure<\/li><\/ul>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-3297179 e-flex e-con-boxed e-con e-parent\" data-id=\"3297179\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t<div class=\"elementor-element elementor-element-7a4514d e-con-full e-flex e-con e-child\" data-id=\"7a4514d\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-0ec1357 elementor-widget elementor-widget-spacer\" data-id=\"0ec1357\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"spacer.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"elementor-spacer\">\n\t\t\t<div class=\"elementor-spacer-inner\"><\/div>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-61c7e72 elementor-widget elementor-widget-image\" data-id=\"61c7e72\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"800\" height=\"545\" src=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/steel-Q345qD-1024x698.png\" class=\"attachment-large size-large wp-image-3499\" alt=\"\" srcset=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/steel-Q345qD-1024x698.png 1024w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/steel-Q345qD-700x477.png 700w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/steel-Q345qD-768x523.png 768w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/steel-Q345qD-18x12.png 18w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/steel-Q345qD-600x409.png 600w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/steel-Q345qD.png 1247w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-75cda67 e-con-full e-flex e-con e-child\" data-id=\"75cda67\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-42e02f8 elementor-widget elementor-widget-text-editor\" data-id=\"42e02f8\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p style=\"text-align: center;\"><span style=\"color: #ff6600;\">Dimensions of Q345qD square and rectangular tubes<\/span><\/p><p><strong>Square tube dimensions:<\/strong> Side length 20 &#8211; 600mm\uff0c4000-12000mm<br \/><strong>Rectangular tube dimensions:<\/strong> 20 &#8211; 800mm<br \/><strong>Wall thickness range:<\/strong> 1.5mm &#8211; 30mm<br \/><strong>Standard lengths:<\/strong> 6 meters, 12 meters<\/p><p style=\"text-align: center;\"><span style=\"color: #ff6600;\">How do you measure the size of steel Q345qD?<\/span><\/p><p>Q345QD square and rectangular tubes are generally used for: <br \/>Outside dimension \u00d7 Outside dimension \u00d7 Wall thickness \u00d7 Length <br \/>It is stated, for example: <br \/>200\u00d7200\u00d710\u00d712000 mm<\/p><p>Meaning: <br \/>200 mm = Outer side length A of the square tube<br \/>200 mm = Outer side length B of the square tube<br \/>10 mm = Wall thickness T<br \/>12000 mm = Length L (commonly 6 meters or 12 meters)<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-89e284c e-con-full e-flex e-con e-child\" data-id=\"89e284c\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t<div class=\"elementor-element elementor-element-7a1a562 elementor-widget elementor-widget-spacer\" data-id=\"7a1a562\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"spacer.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"elementor-spacer\">\n\t\t\t<div class=\"elementor-spacer-inner\"><\/div>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9ce49d3 elementor-widget elementor-widget-image\" data-id=\"9ce49d3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"800\" height=\"534\" src=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Bridge-Building-Q345qd-1024x684.png\" class=\"attachment-large size-large wp-image-3498\" alt=\"\" srcset=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Bridge-Building-Q345qd-1024x684.png 1024w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Bridge-Building-Q345qd-700x467.png 700w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Bridge-Building-Q345qd-768x513.png 768w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Bridge-Building-Q345qd-18x12.png 18w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Bridge-Building-Q345qd-600x401.png 600w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Bridge-Building-Q345qd.png 1225w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-f836966 e-flex e-con-boxed e-con e-parent\" data-id=\"f836966\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-52114b3 elementor-widget elementor-widget-text-editor\" data-id=\"52114b3\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p><span style=\"color: #ff6600;\">Q345QD Chemical Elements\uff1a<\/span><\/p><p>(C)\u200c\uff1a\u22640.18%<br \/>(Si)\u200c\uff1a\u22640.50%\u00a0<br \/>\u200c(Mn)\u200c\uff1a0.90%\u20131.60%<br \/>\u200c(P)\u200c\uff1a\u22640.025%<br \/>\u200c(S)\u200c\uff1a\u22640.025%<br \/>\u200c(Als)\u200c\uff1a\u22650.015%<\/p><p>microalloy elements\uff1aNb\u22640.045%\u3001V\u22640.08%\u3001Ti\u22640.20%<br \/>\u200cresidual elements\uff1aCr\u3001Ni\u3001Cu residual elements\u22640.30%<\/p><p><span style=\"color: #ff6600;\">Q345QD Mechanical Properties\uff1a<\/span><\/p><p>\u00a0(Yield Strength)\u200c\uff1a\u2265345 MPa<br \/>\u00a0(Tensile Strength)\u200c\uff1a<br \/>(Elongation)\u200c\uff1a\u226520%\uff08<br \/>Low-temperature impact toughness \u200c : Under the condition of \u200c-20\u2103\u200c, the V-notch impact energy (KV2) must meet specific standards (usually \u226534J) to ensure the safety of bridge structures in cold regions.<\/p><p><span style=\"color: #ff6600;\">Q345QD Tolerance\uff1a<\/span><\/p><p>Wall thickness tolerance: \u00b110%<br \/>Edge length\/form size deviation: \u00b10.75% to \u00b11.0%<br \/>Bending degree: no more than 2.0mm<br \/>End head skewness: no more than 2.0mm<\/p><p><span style=\"color: #ff6600;\">Q345QD Surface Quality\uff1a<\/span><\/p><p>The surface must not have any bubbles, scars, cracks, folds, inclusions, or indentations of iron oxide. It is also necessary to ensure that the cut is smooth, without burrs or obvious distortions.<\/p><p><span style=\"color: #ff6600;\">Q345QD Welding\uff1a<\/span><\/p><p>Use low-hydrogen welding materials (E5015\/J507 or matching flux-cored welding wire). When the plate thickness is greater than 25mm or the ambient temperature is lower than 0\u2103, preheating to 100\u2013150\u2103 is mandatory. Strictly control the line energy to prevent the thermal affected zone from becoming brittle. After welding, perform 600\u2013640\u2103 stress-relieving heat treatment based on the thickness, and conduct 100% non-destructive testing to ensure that the -20\u2103 impact toughness meets the requirements.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-bb3cdc6 e-flex e-con-boxed e-con e-parent\" data-id=\"bb3cdc6\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-cc74506 elementor-widget elementor-widget-image\" data-id=\"cc74506\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"700\" height=\"700\" src=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345qC-Q345qD-Metal-Beam-Estrikti.png\" class=\"attachment-large size-large wp-image-3506\" alt=\"\" srcset=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345qC-Q345qD-Metal-Beam-Estrikti.png 700w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345qC-Q345qD-Metal-Beam-Estrikti-150x150.png 150w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345qC-Q345qD-Metal-Beam-Estrikti-12x12.png 12w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345qC-Q345qD-Metal-Beam-Estrikti-300x300.png 300w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345qC-Q345qD-Metal-Beam-Estrikti-600x600.png 600w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/Q345qC-Q345qD-Metal-Beam-Estrikti-100x100.png 100w\" sizes=\"(max-width: 700px) 100vw, 700px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-c8f0c9a e-flex e-con-boxed e-con e-parent\" data-id=\"c8f0c9a\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-bb8e956 elementor-widget elementor-widget-text-editor\" data-id=\"bb8e956\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p>\u00a0<\/p><p style=\"text-align: center;\"><span style=\"color: #ff6600;\">What types of <strong><span style=\"color: #000000;\">Q345qD square and rectangular tubes<\/span><\/strong> are there?<\/span><\/p><p><strong>1. According to production process<\/strong><\/p><p><br \/>\u00a0 \u200c\u00b0\u00a0 Seamless square and rectangular tubes<br \/>\u00a0 \u200c\u00b0\u00a0 Welded square and rectangular tubes<\/p><p><strong>2.According to the cross-sectional shape<\/strong><\/p><p><br \/>\u00a0 \u200c\u00b0\u00a0 Square tube<br \/>\u00a0 \u200c\u00b0\u00a0 Rectangular tube<\/p><p><strong>3. According to surface condition<\/strong><\/p><p><br \/>\u00a0 \u200c\u00b0\u00a0 Black pipe (bare pipe)<br \/>\u00a0 \u200c\u00b0\u00a0 Galvanized pipe<br \/>\u00a0 \u200c\u00b0\u00a0 Other coatings<\/p><p style=\"text-align: center;\"><span style=\"color: #ff6600;\">What are the types of <span style=\"color: #000000;\"><strong>Q345qD<\/strong><\/span>?<\/span><\/p><p>\u00a0<\/p><p><strong>1. According to the additional performance requirements:<\/strong><\/p><p><br \/>\u00a0 \u200c\u00b0\u00a0 Ordinary Q345qD: Only meets -20\u2103 impact toughness;<br \/>\u00a0 \u200c\u00b0\u00a0 Z-direction performance type: Q345qD-Z15\/Z25\/Z35<br \/>\u00a0 \u200c\u00b0\u00a0 Weather-resistant composite type: Q345qDNH<\/p><p>\u00a0<\/p><p style=\"text-align: center;\"><span style=\"color: #ff6600;\">What are the different types of <span style=\"color: #000000;\"><strong>Q345<\/strong><\/span>?<\/span><\/p><p>\u00a0<\/p><p>Q345A: No impact test required, no mandatory requirement for low-temperature toughness<br \/>Q345B: 20\u2103<br \/>Q345C: 0\u2103<br \/>Q345D: -20\u2103<br \/>Q345E: -40\u2103<\/p><p>\u00a0<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-ca67ca1 e-flex e-con-boxed e-con e-parent\" data-id=\"ca67ca1\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-931f488 elementor-widget elementor-widget-image\" data-id=\"931f488\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"image.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<img loading=\"lazy\" decoding=\"async\" width=\"800\" height=\"559\" src=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/bridge-steel-Q345qD-1024x716.png\" class=\"attachment-large size-large wp-image-3510\" alt=\"\" srcset=\"https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/bridge-steel-Q345qD-1024x716.png 1024w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/bridge-steel-Q345qD-700x489.png 700w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/bridge-steel-Q345qD-768x537.png 768w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/bridge-steel-Q345qD-18x12.png 18w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/bridge-steel-Q345qD-600x419.png 600w, https:\/\/jblstainless.com\/wp-content\/uploads\/2026\/07\/bridge-steel-Q345qD.png 1037w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/>\t\t\t\t\t\t\t\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-05d0aad elementor-widget elementor-widget-spacer\" data-id=\"05d0aad\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"spacer.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t<div class=\"elementor-spacer\">\n\t\t\t<div class=\"elementor-spacer-inner\"><\/div>\n\t\t<\/div>\n\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-99182f9 elementor-align-center elementor-widget elementor-widget-button\" data-id=\"99182f9\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"button.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<div class=\"elementor-button-wrapper\">\n\t\t\t\t\t<a class=\"elementor-button elementor-button-link elementor-size-sm\" href=\"https:\/\/jblstainless.com\/it\/contatto\/\">\n\t\t\t\t\t\t<span class=\"elementor-button-content-wrapper\">\n\t\t\t\t\t\t<span class=\"elementor-button-icon\">\n\t\t\t\t<svg aria-hidden=\"true\" class=\"e-font-icon-svg e-fas-baby-carriage\" viewbox=\"0 0 512 512\" xmlns=\"http:\/\/www.w3.org\/2000\/svg\"><path d=\"M144.8 17c-11.3-17.8-37.2-22.8-54-9.4C35.3 51.9 0 118 0 192h256L144.8 17zM496 96h-48c-35.3 0-64 28.7-64 64v64H0c0 50.6 23 96.4 60.3 130.7C25.7 363.6 0 394.7 0 432c0 44.2 35.8 80 80 80s80-35.8 80-80c0-8.9-1.8-17.2-4.4-25.2 21.6 5.9 44.6 9.2 68.4 9.2s46.9-3.3 68.4-9.2c-2.7 8-4.4 16.3-4.4 25.2 0 44.2 35.8 80 80 80s80-35.8 80-80c0-37.3-25.7-68.4-60.3-77.3C425 320.4 448 274.6 448 224v-64h48c8.8 0 16-7.2 16-16v-32c0-8.8-7.2-16-16-16zM80 464c-17.6 0-32-14.4-32-32s14.4-32 32-32 32 14.4 32 32-14.4 32-32 32zm320-32c0 17.6-14.4 32-32 32s-32-14.4-32-32 14.4-32 32-32 32 14.4 32 32z\"><\/path><\/svg>\t\t\t<\/span>\n\t\t\t\t\t\t\t\t\t<span class=\"elementor-button-text\">Click Here   Inquiry Price<\/span>\n\t\t\t\t\t<\/span>\n\t\t\t\t\t<\/a>\n\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t<div class=\"elementor-element elementor-element-8fa0625 e-flex e-con-boxed e-con e-parent\" data-id=\"8fa0625\" data-element_type=\"container\" data-e-type=\"container\">\n\t\t\t\t\t<div class=\"e-con-inner\">\n\t\t\t\t<div class=\"elementor-element elementor-element-325ce19 elementor-widget elementor-widget-text-editor\" data-id=\"325ce19\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<h4>\u00a0<\/h4><h4 style=\"text-align: center;\"><span style=\"color: #ff6600;\">Questions you might have about Q345qD?<\/span><\/h4><p><span style=\"color: #ff6600;\">Why do so many people choose JBL&#8217;s Q345?<\/span><\/p><p>The core advantage of Q345D square tubes lies in the balance between mechanical properties and processing adaptability. Its yield strength exceeds 345 megapascals, and Q345 Rectangular Steel Pipe and Square Steel Tube the tensile strength ranges from 470 to 630 megapascals. The elongation rate is usually over 21%, which means it can both resist deformation and have certain ductility when bearing loads, and is less likely to suddenly break. Development of Q345qD Thicker Bridge Steel Plate of 130mm,Trace amounts of alloy elements such as vanadium, titanium, and niobium are added to the material, which refine the grains and enhance the welding performance &#8211; under conventional manual arc welding, gas shielded welding, or submerged arc welding processes, as long as the preheating temperature is properly controlled (generally not lower than 100\u00b0C), the weld seam heat affected zone is less likely to develop cold cracks. In addition, Q345 low carbon steel require an impact energy of no less than 34 joules (-20\u00b0C) in the cold environment, Q345q Series | Structural Steel for Bridge enabling them to maintain reliable operation in northern cold regions or outdoor structures of cold chain facilities.<\/p><p><span style=\"color: #ff6600;\">Is Q345QD resistant to low temperatures?<\/span><\/p><p>yes<\/p><p><span style=\"color: #ff6600;\">What are the differences between Q345QD and Q345B?<\/span><\/p><table><thead><tr><th align=\"left\">&#8220;Comparison dimension&#8221;<\/th><th align=\"left\">\u200c<strong>Q345qD<\/strong>\u200c (steel for bridge)<\/th><th align=\"left\">\u200c<strong>Q345B<\/strong>\u200c (General-purpose structural steel)<\/th><\/tr><\/thead><tbody><tr><td align=\"left\">\u200cMeaning of grade\u200c<\/td><td align=\"left\">Q(bend)+345(strength)+\u200cq\u200c(bridge)+D(grade)<\/td><td align=\"left\">Q(Bend)+345(strength)+B(Grade)<\/td><\/tr><tr><td align=\"left\">\u200cexecutive standard\u200c<\/td><td align=\"left\">\u200c<strong>GB\/T 714<\/strong>\u200c (Steel for bridge structures)<\/td><td align=\"left\">\u200c<strong>GB\/T 1591<\/strong>\u200c (Low-Alloy High-Tensile Structural Steel<span style=\"font-family: inherit; font-size: inherit;\">)<\/span><\/td><\/tr><tr><td align=\"left\">\u200cmain application\u200c<\/td><td align=\"left\">It is specifically used for the main beams and key load-bearing components of \u200c railway\/highway Bridges \u200c<\/td><td align=\"left\">General structures such as buildings, vehicles, and general machinery \u200c\u200c<\/td><\/tr><tr><td align=\"left\">\u200cImpact test temperature\u200c<\/td><td align=\"left\">\u200c<strong>-20\u2103<\/strong>\u200c (High low-temperature toughness is required)<\/td><td align=\"left\">\u200c<strong>20\u2103<\/strong>\u200c (Impact at normal temperature)<\/td><\/tr><tr><td align=\"left\">\u200c<strong> (P) Content upper limit<\/strong>\u200c<\/td><td align=\"left\">\u2264 \u200c<strong>0.025%<\/strong>\u200c\u00a0<\/td><td align=\"left\">\u2264 \u200c<strong>0.040%<\/strong>\u200c<\/td><\/tr><tr><td align=\"left\">\u200c<strong> (S) Content upper limit<\/strong>\u200c<\/td><td align=\"left\">\u2264 \u200c<strong>0.025%<\/strong>\u200c\u00a0<\/td><td align=\"left\">\u2264 \u200c<strong>0.040%<\/strong>\u200c<\/td><\/tr><tr><td align=\"left\">\u200c<strong>(C) Content upper limit<\/strong>\u200c<\/td><td align=\"left\">\u00a0\u2264 \u200c<strong>0.18%<\/strong>\u200c\u00a0<\/td><td align=\"left\">\u2264 \u200c<strong>0.20%<\/strong>\u200c<\/td><\/tr><tr><td align=\"left\">\u200cPerformance focus\u200c<\/td><td align=\"left\">High toughness, fatigue resistance, atmospheric corrosion resistance and good weldability<\/td><td align=\"left\">It has good comprehensive mechanical properties and a relatively low cost<\/td><\/tr><\/tbody><\/table>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<div class=\"elementor-element elementor-element-9aa8e5e elementor-widget elementor-widget-text-editor\" data-id=\"9aa8e5e\" data-element_type=\"widget\" data-e-type=\"widget\" data-widget_type=\"text-editor.default\">\n\t\t\t\t<div class=\"elementor-widget-container\">\n\t\t\t\t\t\t\t\t\t<p><span style=\"color: #ff6600;\">Can Q345QD square and rectangular tubes be exported?<\/span><\/p><p>yes<\/p><p><span style=\"color: #ff6600;\">What is the biggest difference between Q345QD square\/rectangular tubes and ordinary square tubes?<\/span><\/p><p>Q235 square tubes are widely used in ordinary building frameworks. Their yield strength meets the basic load-bearing requirements and the cost is relatively low. On the other hand, Q345 square and rectangular tubes, due to their higher strength and toughness, are more suitable for scenarios with higher requirements for load-bearing capacity, such as large bridges and heavy machinery.<\/p><p><span style=\"color: #ff6600;\">Is Q345QD square and rectangular tube resistant to fatigue?<\/span><\/p><p>better.<\/p><p><span style=\"color: #ff6600;\">What raw materials are used for Bridge Building Q345qd?<\/span><\/p><p>Q345QD hot-rolled steel coil \/ Q345QD steel plate<\/p><p><span style=\"color: #ff6600;\">Does the thickness of the raw material affect the performance of square and rectangular tubes?<\/span><\/p><p>yes<\/p><p><span style=\"color: #ff6600;\">large thick plate bridge steel of Q345qD develop residual stress?<\/span><\/p><p>yes<\/p><p><span style=\"color: #ff6600;\">Can Q345qD steel plates are structural steel plates\u00a0 undergo secondary welding?<\/span><\/p><p>yes<\/p><p><span style=\"color: #ff6600;\">Are Q345QD square and rectangular tubes suitable for high-rise buildings?<\/span><\/p><p>yes<\/p><p><span style=\"color: #ff6600;\">How can \u00a0large thick plate bridge steel of Q345qD be protected against rust?<\/span><\/p><p>Hot-dip galvanizing \/ Spray coating composite coating \/ Paint coating \/ Gas-phase rust prevention \/ Cathodic protection<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t<\/div>","protected":false},"excerpt":{"rendered":"<p>Mild Steel Q345qd Hot Rolled Carbon Square and rectangular tubes Steel for Bridge Building supports 180\u00b0 cold bending without cracking, with a bend diameter \u22642 times the plate thickness, and offers anti-laminar tearing grades up to Z15\/Z25\/Z35, meeting the requirements for thick plates (&gt;40mm).<\/p>\n<p><span style=\"color: #ff6600;\">&#8220;Q&#8221; represents the yield strength. <\/span><\/p>\n<p><span style=\"color: #ff6600;\">&#8220;345&#8221; indicates the minimum yield strength of 345 MPa. <\/span><\/p>\n<p><span style=\"color: #ff6600;\">&#8220;q&#8221; refers to steel for bridges.<\/span><\/p>\n<p><span style=\"color: #ff6600;\"> &#8220;D&#8221; &#8211; 20\u2103 low-temperature impact toughness.<\/span><\/p>","protected":false},"featured_media":3489,"template":"","meta":{"_eb_attr":""},"product_brand":[],"product_cat":[68],"product_tag":[],"class_list":["post-3485","product","type-product","status-publish","has-post-thumbnail","product_cat-high-strength-steel-plate","first","instock","shipping-taxable","product-type-simple"],"_links":{"self":[{"href":"https:\/\/jblstainless.com\/it\/wp-json\/wp\/v2\/product\/3485","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/jblstainless.com\/it\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/jblstainless.com\/it\/wp-json\/wp\/v2\/types\/product"}],"version-history":[{"count":5,"href":"https:\/\/jblstainless.com\/it\/wp-json\/wp\/v2\/product\/3485\/revisions"}],"predecessor-version":[{"id":3522,"href":"https:\/\/jblstainless.com\/it\/wp-json\/wp\/v2\/product\/3485\/revisions\/3522"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/jblstainless.com\/it\/wp-json\/wp\/v2\/media\/3489"}],"wp:attachment":[{"href":"https:\/\/jblstainless.com\/it\/wp-json\/wp\/v2\/media?parent=3485"}],"wp:term":[{"taxonomy":"product_brand","embeddable":true,"href":"https:\/\/jblstainless.com\/it\/wp-json\/wp\/v2\/product_brand?post=3485"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/jblstainless.com\/it\/wp-json\/wp\/v2\/product_cat?post=3485"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/jblstainless.com\/it\/wp-json\/wp\/v2\/product_tag?post=3485"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}