{"id":650,"date":"2026-03-03T02:34:08","date_gmt":"2026-03-03T02:34:08","guid":{"rendered":"https:\/\/www.jccncmachining.com\/material\/\/"},"modified":"2026-03-03T02:34:08","modified_gmt":"2026-03-03T02:34:08","slug":"4340-steel","status":"publish","type":"material_model","link":"https:\/\/www.jccncmachining.com\/ko\/materials\/steel\/4340-steel\/","title":{"rendered":"4340 Steel"},"content":{"rendered":"

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4340 Steel Machining Capabilities<\/h3>\n\n\n\n\n\n\n\n\n
Capability<\/th>\nTechnical Description<\/th>\nJucheng Advantage<\/th>\n<\/tr>\n<\/thead>\n
Heavy Section Machining<\/strong><\/td>\n4340 maintains its high strength even in very thick sections. We machine large diameter drive components from solid forged billets.<\/td>\nOur high-torque Mazak CNC centers handle the extreme toughness of 4340, maintaining dimensional stability across large workpieces.<\/td>\n<\/tr>\n
Through-Hardened Finishing<\/strong><\/td>\nMachining 4340 after it has been heat-treated to 36-40 HRC for maximum fatigue life and strength.<\/td>\nWe use specialized ceramic and CBN tooling to cut through hardened 4340, providing finished parts with superior surface integrity.<\/td>\n<\/tr>\n
5-Axis Structural Milling<\/strong><\/td>\nMilling complex, high-stress structural airframe components with intricate geometries.<\/td>\nJucheng’s 5-axis capability ensures that complex aerospace fittings are machined in minimal setups, guaranteeing geometric alignment.<\/td>\n<\/tr>\n
Super-Precision Grinding<\/strong><\/td>\nAchieving Ra 0.2\u03bcm finishes on critical bearing and seal journals for high-speed rotating parts.<\/td>\nEssential for landing gear and crankshafts where surface defects could lead to catastrophic fatigue failure.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n

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Fabrication Guidelines for 4340 Alloy Steel<\/h3>\n

Ultimate Deep Hardenability:<\/strong>
\n4340 is famous for its “deep hardening” characteristics due to the Nickel content. It can be hardened to high levels in sections where 4140 would fail. Tip:<\/strong> Ideal for large, critical shafts over 3 inches in diameter.<\/p>\n

Machinability Rating:<\/strong>
\n4340 is tougher and more abrasive than 4140. Machinability is approx. 55% of 1212. Tip:<\/strong> We use lower cutting speeds and higher-rigidity workholding to prevent tool chatter on this tough alloy.<\/p>\n

Hydrogen Embrittlement Risk:<\/strong>
\nHigh-strength 4340 is susceptible to hydrogen embrittlement during plating. Tip:<\/strong> If parts are Zinc or Cadmium plated, we perform mandatory “bake-out” cycles immediately after plating to ensure structural safety.<\/p>\n

Heat Treatment Precision:<\/strong>
\nTo reach peak performance, 4340 requires oil quenching. We recommend normalized and stress-relieved stock to minimize movement during the quenching process.<\/p>\n<\/div>\n

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Primary Applications<\/h3>\n

Aerospace & Aviation<\/strong>
\nAircraft landing gear, structural airframe members, and engine attachment fittings where failure is not an option.<\/p>\n

Heavy Power Transmission<\/strong>
\nHigh-torque drive shafts, heavy-duty gears, and crankshafts for commercial and military marine engines.<\/p>\n

Defense & Ordinance<\/strong>
\nGun barrels, breech blocks, and high-strength fasteners that must withstand extreme shock and impact loads.<\/p>\n

Motorsport<\/strong>
\nUltra-high performance connecting rods and axles for racing engines that operate under extreme cyclic stress.<\/p>\n<\/div>","protected":false},"excerpt":{"rendered":"

4340 Steel Machining Capabilities Capability Technical Description Jucheng Advantage Heavy Section Machining 4340 maintains its high strength even in very thick sections. We machine large diameter drive components from solid forged billets. Our high-torque Mazak CNC centers handle the extreme toughness of 4340, maintaining dimensional stability across large workpieces. Through-Hardened Finishing Machining 4340 after it […]<\/p>\n","protected":false},"featured_media":651,"template":"","meta":[],"class_list":["post-650","material_model","type-material_model","status-publish","has-post-thumbnail","hentry"],"_links":{"self":[{"href":"https:\/\/www.jccncmachining.com\/ko\/wp-json\/wp\/v2\/material_model\/650","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.jccncmachining.com\/ko\/wp-json\/wp\/v2\/material_model"}],"about":[{"href":"https:\/\/www.jccncmachining.com\/ko\/wp-json\/wp\/v2\/types\/material_model"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.jccncmachining.com\/ko\/wp-json\/wp\/v2\/media\/651"}],"wp:attachment":[{"href":"https:\/\/www.jccncmachining.com\/ko\/wp-json\/wp\/v2\/media?parent=650"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}