{"id":16026,"date":"2026-06-23T09:59:46","date_gmt":"2026-06-23T01:59:46","guid":{"rendered":"https:\/\/aobosteel.com\/?p=16026"},"modified":"2026-06-23T09:59:47","modified_gmt":"2026-06-23T01:59:47","slug":"4340-steel-properties","status":"publish","type":"post","link":"https:\/\/aobosteel.com\/pt\/blog\/4340-steel-properties\/","title":{"rendered":"Propriedades do a\u00e7o 4340: Composi\u00e7\u00e3o e tratamento t\u00e9rmico"},"content":{"rendered":"<h1 class=\"wp-block-heading has-text-align-center\" id=\"h-4340-steel-properties\">4340 Propriedades do A\u00e7o<\/h1>\n\n\n\n<p class=\"wp-block-paragraph\">O a\u00e7o 4340 \u00e9 um a\u00e7o-liga de n\u00edquel-cromo-molibd\u00eanio com teor m\u00e9dio de carbono (AISI\/SAE 4340). Pertence \u00e0 classe dos a\u00e7os estruturais de ultra-alta resist\u00eancia e \u00e9 valorizado por sua temperabilidade em altas temperaturas, alta tenacidade em altas resist\u00eancias e excelente desempenho \u00e0 fadiga. Suas aplica\u00e7\u00f5es t\u00edpicas incluem trens de pouso de aeronaves, eixos e engrenagens de grande porte, virabrequins e outras pe\u00e7as que suportam altas tens\u00f5es em se\u00e7\u00f5es espessas.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u00c9 importante definir expectativas desde o in\u00edcio. O a\u00e7o 4340 n\u00e3o \u00e9 um a\u00e7o ferramenta. Trata-se de um a\u00e7o-liga estrutural e n\u00e3o foi projetado para a resist\u00eancia ao desgaste ou a dureza a quente necess\u00e1rias para trabalhos de corte e usinagem. Se voc\u00ea estiver escolhendo um material para uma matriz, pun\u00e7\u00e3o ou ferramenta de trabalho a quente, consulte a compara\u00e7\u00e3o com os a\u00e7os ferramenta mais adiante.<\/p>\n\n\n\n<h2 id=\"h-international-equivalents\" class=\"wp-block-heading\">Equivalentes Internacionais<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>Padr\u00e3o<\/td><td>Designa\u00e7\u00e3o<\/td><\/tr><tr><td>AISI\/SAE (EUA)<\/td><td>4340<\/td><\/tr><tr><td>GB (China)<\/td><td>40CrNiMoA<\/td><\/tr><tr><td>JIS (Jap\u00e3o)<\/td><td>SNCM439<\/td><\/tr><tr><td>DIN\/EN (Alemanha)<\/td><td>1,6565 (40NiCrMo6)<\/td><\/tr><tr><td>BS (Reino Unido)<\/td><td>817M40 (EN24)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Esses a\u00e7os s\u00e3o equivalentes aproximados, e n\u00e3o correspond\u00eancias exatas. O SNCM439 \u00e9 o que mais se assemelha ao AISI 4340 em termos de teor de n\u00edquel. O GB 40CrNiMoA situa-se na extremidade inferior da faixa de n\u00edquel, com 1,25 a 1,65%, em compara\u00e7\u00e3o com 1,65 a 2,00% para o 4340, e o 817M40 apresenta um teor de cromo mais elevado. Confirme a especifica\u00e7\u00e3o exata ao realizar substitui\u00e7\u00f5es cruzadas.<\/p>\n\n\n\n<h2 id=\"h-chemical-composition\" class=\"wp-block-heading\">Composi\u00e7\u00e3o Qu\u00edmica<\/h2>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>Elemento<\/td><td>AISI 4340<\/td><td>GB 40CrNiMoA<\/td><\/tr><tr><td>Carbono \u00a9<\/td><td>0,38 a 0,43<\/td><td>0,37 a 0,44<\/td><\/tr><tr><td>Mangan\u00eas (Mn)<\/td><td>0,60 a 0,80<\/td><td>0,50 a 0,80<\/td><\/tr><tr><td>Sil\u00edcio (Si)<\/td><td>0,15 a 0,35<\/td><td>0,17 a 0,37<\/td><\/tr><tr><td>N\u00edquel (Ni)<\/td><td>1,65 a 2,00<\/td><td>1,25 a 1,65<\/td><\/tr><tr><td>Cromo (Cr)<\/td><td>0,70 a 0,90<\/td><td>0,60 a 0,90<\/td><\/tr><tr><td>Molibd\u00eanio (Mo)<\/td><td>0,20 a 0,30<\/td><td>0,15 a 0,25<\/td><\/tr><tr><td>F\u00f3sforo (P)<\/td><td>0,035 m\u00e1x.<\/td><td>0,035 m\u00e1x.<\/td><\/tr><tr><td>Enxofre (S)<\/td><td>0,040 m\u00e1ximo<\/td><td>0,035 m\u00e1x.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Valores em porcentagem. A combina\u00e7\u00e3o de n\u00edquel, cromo e molibd\u00eanio \u00e9 o que confere ao a\u00e7o 4340 suas caracter\u00edsticas. O n\u00edquel aumenta a tenacidade, especialmente em baixas temperaturas, e atua em conjunto com o cromo e o molibd\u00eanio para aumentar a temperabilidade em toda a espessura da pe\u00e7a. O molibd\u00eanio tamb\u00e9m reduz a suscetibilidade \u00e0 fragiliza\u00e7\u00e3o por revenido e ajuda o a\u00e7o a manter sua resist\u00eancia durante o processo de revenido.<\/p>\n\n\n\n<h2 id=\"h-mechanical-properties-and-heat-treatment-response\" class=\"wp-block-heading\">Propriedades mec\u00e2nicas e resposta ao tratamento t\u00e9rmico<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">O a\u00e7o 4340 atinge uma resist\u00eancia muito alta, mantendo uma tenacidade utiliz\u00e1vel, e esse equil\u00edbrio \u00e9 sua propriedade definidora. Os valores abaixo representam faixas t\u00edpicas para t\u00eampera em \u00f3leo seguida de revenido. Os valores reais dependem da dimens\u00e3o da se\u00e7\u00e3o transversal, da temperatura exata de revenido e da norma de ensaio.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>Condi\u00e7\u00e3o<\/td><td>Tra\u00e7\u00e3o<\/td><td>Colheita<\/td><td>Alongamento<\/td><td>Dureza<\/td><\/tr><tr><td>Recozido<\/td><td>~745 MPa<\/td><td>~470 MPa<\/td><td>~22%<\/td><td>~217 HB<\/td><\/tr><tr><td>Q&amp;T, temperatura baixa (~200\u00b0C)<\/td><td>1800 a 2000 MPa<\/td><td>1500 a 1700 MPa<\/td><td>8 a 12%<\/td><td>50 a 54 HRC<\/td><\/tr><tr><td>Q&amp;T, temperatura m\u00e9dia (~400\u00b0C)<\/td><td>1300 a 1500 MPa<\/td><td>1150 a 1350 MPa<\/td><td>10 a 14%<\/td><td>40 a 45 HRC<\/td><\/tr><tr><td>Q&amp;T, alta temperatura (~600\u00b0C)<\/td><td>1000 a 1200 MPa<\/td><td>850 a 1000 MPa<\/td><td>14 a 20%<\/td><td>32 a 38 HRC<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">A dureza ap\u00f3s t\u00eampera \u00e9 de aproximadamente 55-57 HRC antes do revenido. O revenido sacrifica dureza e resist\u00eancia em prol de tenacidade e ductilidade, portanto, o ponto de trabalho \u00e9 escolhido para corresponder \u00e0 carga aplicada.<\/p>\n\n\n\n<h3 id=\"h-tempering-ranges-to-watch\" class=\"wp-block-heading\">Faixas de t\u00eampera a serem observadas<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Duas formas de fragiliza\u00e7\u00e3o s\u00e3o relevantes durante o revenimento do a\u00e7o 4340. O revenimento na faixa de 230 \u00b0C a 370 \u00b0C pode causar fragiliza\u00e7\u00e3o da martensita revenida, reduzindo a resist\u00eancia ao impacto, mesmo que a dureza permane\u00e7a alta. Al\u00e9m disso, o resfriamento lento entre aproximadamente 375 \u00b0C e 575 \u00b0C pode causar fragiliza\u00e7\u00e3o revers\u00edvel por revenimento, impulsionada pela segrega\u00e7\u00e3o de f\u00f3sforo nos contornos de gr\u00e3o da austenita pr\u00e9via. Para pe\u00e7as sujeitas a impacto, os fabricantes geralmente mant\u00eam o revenimento abaixo de cerca de 230 \u00b0C ou acima de cerca de 425 \u00b0C e resfriam rapidamente a partir da faixa de alta temperatura de revenimento. O molibd\u00eanio presente no a\u00e7o 4340 reduz essa sensibilidade, mas n\u00e3o a elimina completamente.<\/p>\n\n\n\n<h2 id=\"h-hardenability-the-main-advantage\" class=\"wp-block-heading\">Temperabilidade: a principal vantagem<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">A alta temperabilidade \u00e9 o motivo pelo qual os engenheiros preferem o a\u00e7o 4340 em vez de a\u00e7os-liga mais leves. O sistema n\u00edquel-cromo-molibd\u00eanio permite que o 4340 se transforme em martensita em se\u00e7\u00f5es espessas durante a t\u00eampera em \u00f3leo, de modo que um eixo grande ou um componente de trem de pouso possa atingir dureza quase uniforme da superf\u00edcie ao n\u00facleo. A\u00e7os mais leves, como o 4140, endurecem bem em barras menores, mas tendem a amolecer no centro de se\u00e7\u00f5es espessas, deixando um n\u00facleo mais macio e fr\u00e1gil. Quando as propriedades completas s\u00e3o necess\u00e1rias em se\u00e7\u00f5es com mais de 75-100 mm, aproximadamente, o 4340 costuma ser a escolha pr\u00e1tica.<\/p>\n\n\n\n<h2 id=\"h-4340-vs-4140\" class=\"wp-block-heading\">4340 vs 4140<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><a href=\"https:\/\/aobosteel.com\/pt\/blog\/4140-steel-properties\/\">4140<\/a> O a\u00e7o 4140 e o 4340 compartilham a base de cromo-molibd\u00eanio. A diferen\u00e7a est\u00e1 no n\u00edquel. O 4140 praticamente n\u00e3o cont\u00e9m n\u00edquel, enquanto o 4340 apresenta de 1,65% a 2,00%, e \u00e9 esse n\u00edquel que os diferencia na pr\u00e1tica.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>Propriedade<\/td><td>4340<\/td><td>4140<\/td><\/tr><tr><td>Endurecimento profundo<\/td><td>Excelente em se\u00e7\u00f5es pesadas<\/td><td>Moderado<\/td><\/tr><tr><td>Resist\u00eancia em alta for\u00e7a<\/td><td>Excelente<\/td><td>Bom<\/td><\/tr><tr><td>resist\u00eancia \u00e0 fadiga<\/td><td>Mais alto<\/td><td>Bom<\/td><\/tr><tr><td>Resist\u00eancia a baixas temperaturas<\/td><td>Bom<\/td><td>Adequado<\/td><\/tr><tr><td>Custo relativo<\/td><td>Maior (teor de n\u00edquel)<\/td><td>Inferior<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">Escolha o a\u00e7o 4340 em vez do 4140 quando for necess\u00e1ria dureza m\u00e1xima em se\u00e7\u00f5es espessas que o 4140 n\u00e3o consegue endurecer completamente, quando for exigida tenacidade m\u00e1xima em alta resist\u00eancia, quando a pe\u00e7a estiver sujeita a carregamento de fadiga, como componentes de aeronaves e eixos de servi\u00e7o pesado, ou quando a tenacidade a baixas temperaturas for importante. Para se\u00e7\u00f5es mais leves com resist\u00eancia moderada, o a\u00e7o 4140 geralmente \u00e9 a op\u00e7\u00e3o mais econ\u00f4mica.<\/p>\n\n\n\n<h2 id=\"h-4340-vs-tool-steel\" class=\"wp-block-heading\">A\u00e7o 4340 versus a\u00e7o ferramenta<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Essa \u00e9 a distin\u00e7\u00e3o que atrai muitos compradores a esta p\u00e1gina, por isso vale a pena ser direto. O a\u00e7o 4340 n\u00e3o substitui o a\u00e7o ferramenta em trabalhos de corte e usinagem.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><tbody><tr><td>Exig\u00eancia<\/td><td>4340<\/td><td>A\u00e7o ferramenta (D2 \/ H13)<\/td><\/tr><tr><td>Resist\u00eancia ao desgaste<\/td><td>Baixo<\/td><td>Alto, devido ao volume de carboneto<\/td><\/tr><tr><td>Dureza quente<\/td><td>Pobre<\/td><td>Bom (H13)<\/td><\/tr><tr><td>reten\u00e7\u00e3o de borda<\/td><td>Pobre<\/td><td>Bom<\/td><\/tr><tr><td>Dureza m\u00e1xima pr\u00e1tica<\/td><td>~50 a 55 HRC<\/td><td>58 a 64 HRC<\/td><\/tr><tr><td>Resist\u00eancia estrutural com tenacidade<\/td><td>Excelente<\/td><td>Moderado<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<p class=\"wp-block-paragraph\">O a\u00e7o 4340 \u00e9 a melhor op\u00e7\u00e3o quando a pe\u00e7a \u00e9 estrutural e requer extrema resist\u00eancia e tenacidade em temperaturas ambiente ou moderadas. O a\u00e7o ferramenta \u00e9 a melhor escolha quando a pe\u00e7a precisa resistir ao desgaste, manter o fio de corte ou permanecer dura em altas temperaturas. Uma matriz para trabalho a frio exige... <a href=\"https:\/\/aobosteel.com\/pt\/d2-tool-steel\/\">D2<\/a> ou <a href=\"https:\/\/aobosteel.com\/pt\/a2-tool-steel\/\">A2<\/a>. Uma matriz de trabalho a quente ou ferramenta de extrus\u00e3o requer <a href=\"https:\/\/aobosteel.com\/pt\/h13-tool-steel\/\">H13<\/a> ou H11. O uso do a\u00e7o 4340 nessas fun\u00e7\u00f5es resulta em desgaste e deforma\u00e7\u00e3o prematuros.<\/p>\n\n\n\n<h2 id=\"h-common-applications\" class=\"wp-block-heading\">Aplica\u00e7\u00f5es comuns<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">O a\u00e7o 4340 \u00e9 encontrado em trens de pouso e acess\u00f3rios estruturais de aeronaves, eixos de helic\u00f3pteros e motores, eixos de transmiss\u00e3o e de servi\u00e7o pesado, engrenagens, virabrequins, parafusos de alta resist\u00eancia e canos de armas. Pe\u00e7as aeroespaciais cr\u00edticas em termos de fadiga s\u00e3o frequentemente fabricadas com a\u00e7o 4340 refundido a v\u00e1cuo (VAR ou ESR) para reduzir inclus\u00f5es e aumentar a vida \u00fatil \u00e0 fadiga, uma vez que um a\u00e7o mais limpo resiste ao in\u00edcio de trincas sob carga c\u00edclica.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/aobosteel.com\/pt\/blog\/4140-steel-properties\/\">Propriedades do a\u00e7o 4140<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/aobosteel.com\/pt\/d2-steel-vs-4140\/\">A\u00e7o ferramenta 4140 vs D2<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/aobosteel.com\/pt\/4140-vs-h13\/\">A\u00e7o ferramenta 4140 vs H13<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/aobosteel.com\/pt\/o-que-e-aco-para-ferramentas\/\">O que \u00e9 a\u00e7o ferramenta?<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/aobosteel.com\/pt\/how-to-select-tool-steels\/\">Guia de Sele\u00e7\u00e3o de A\u00e7os para Ferramentas<\/a><\/li>\n<\/ul>","protected":false},"excerpt":{"rendered":"<p>4340 Steel Properties 4340 is a medium-carbon nickel-chromium-molybdenum alloy steel (AISI\/SAE 4340). It belongs to the ultra-high-strength structural steels and is valued for deep hardenability, high toughness at high strength, and strong fatigue performance. Typical uses are aircraft landing gear, heavy-duty shafts and axles, gears, crankshafts, and other parts that carry high stress in thick [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":16027,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_uag_custom_page_level_css":"","site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"disabled","ast-breadcrumbs-content":"","ast-featured-img":"disabled","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"set","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"categories":[22],"tags":[],"class_list":["post-16026","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-blog"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v27.9 (Yoast SEO v27.9) - https:\/\/yoast.com\/product\/yoast-seo-premium-wordpress\/ -->\n<title>4340 Steel Properties: Composition and Heat Treatment - AoboSteel<\/title>\n<meta name=\"description\" content=\"4340 (40CrNiMoA) is a Ni-Cr-Mo alloy steel with deep hardenability and high toughness. 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