{"id":11734,"date":"2026-01-04T11:32:34","date_gmt":"2026-01-04T03:32:34","guid":{"rendered":"https:\/\/aobosteel.com\/?page_id=11734"},"modified":"2026-06-06T11:46:39","modified_gmt":"2026-06-06T03:46:39","slug":"o2-tool-steel-heat-treatment","status":"publish","type":"page","link":"https:\/\/aobosteel.com\/ko\/o2-tool-steel-heat-treatment\/","title":{"rendered":"O2 Tool Steel Heat Treatment Guide"},"content":{"rendered":"
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Home<\/mark> <\/a>> Tool Steel Heat Treatment Technical Center<\/mark> <\/a> > O2 Tool Steel Heat Treatment Guide<\/h6><\/div>\n\n\n\n

Aobo Steel | Global Tool Steel Supplier in China<\/em><\/h4><\/div>\n\n\n\n

O2 Tool Steel Heat Treatment Guide<\/h1>

Heat treatment guidance for O2 tool steel (DIN 1.2842\/JIS SKS31), focusing on wear resistance, machinability, and dimensional stability for cold-work tooling applications.<\/p><\/div>\n\n\n\n

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O2 tool steel<\/a> is an oil-quenched cold work tool steel with high hardness, high wear resistance, and minimal deformation during heat treatment. Compared with water-quenched steel, O2 steel exhibits better dimensional stability and higher toughness after complete quenching\u00a011<\/a><\/sup>. The equivalent grades of O2 tool steel include:<\/p>\n\n\n\n

Standard<\/th>Grade<\/th><\/tr><\/thead>
EN\/DIN<\/td>1.2842 \/ 90MnCrV8<\/td><\/tr>
JIS<\/td>SKS31<\/td><\/tr>
GB<\/td>9Mn2V<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

A Quick Checklist of O2 Tool Steel Heat Treatment<\/h2>\n\n\n\n

Follow these sequential steps for proper heat treatment of O2 tool steel: preheating, hardening (austenitizing), oil quenching, and tempering.
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  1. Preheating<\/strong><\/strong>

    Preheat to 649\u2013677\u00b0C (1200\u20131250\u00b0F) until evenly heated. Reduces thermal shock and the risk of deformation or cracking.<\/p> <\/li>

  2. Austenitizing (Hardening)<\/strong><\/strong>

    Heat to 760\u2013800\u00b0C (1400\u20131472\u00b0F). Alloy carbides dissolve, and the microstructure transforms to austenite.<\/p> <\/li>

  3. Quenching<\/strong><\/strong>

    Quench in oil. Stop when the workpiece reaches 66\u201393\u00b0C (150\u2013200\u00b0F).<\/p> <\/li>

  4. Tempering<\/strong><\/strong>

    Begin immediately once the workpiece cools to 52\u201365\u00b0C (125\u2013150\u00b0F). Temper at 150\u2013260\u00b0C (300\u2013500\u00b0F). Minimum soak: 2 hours per inch (4.7 min\/mm) of cross-section.<\/p> <\/li><\/ol><\/div>\n\n\n\n

    Heat Treatment Process<\/h2>\n\n\n\n

    Preheating<\/h3>\n\n\n\n

    Preheat to 649\u2013677\u00b0C (1200\u20131250\u00b0F) and hold until the workpiece is uniformly heated throughout. This reduces thermal shock and the risk of deformation or cracking when the steel enters the austenitizing furnace.<\/p>\n\n\n\n

    Austenitizing<\/h3>\n\n\n\n

    Heat to 760\u2013800\u00b0C (1400\u20131472\u00b0F). At this temperature, alloy carbides dissolve and the microstructure transforms to austenite. 790\u00b0C (1450\u00b0F) is the recommended standard temperature for most applications. Control soak time carefully \u2014 excessive soaking raises retained austenite content and reduces final hardness.<\/p>\n\n\n\n

    Quenching<\/h3>\n\n\n\n

    Quench in oil, stopping when the workpiece reaches 66\u201393\u00b0C (150\u2013200\u00b0F). Maintain quenching oil temperature between 50\u201370\u00b0C (120\u2013160\u00b0F). Do not use water or brine \u2014 the risk of cracking is severe. Do not wrap in stainless foil, as it impedes oil contact.<\/p>\n\n\n\n

    \"O2
    O2 Tool Steel Isothermal Transformation Diagram<\/figcaption><\/figure>\n\n\n\n

    Tempering<\/h3>\n\n\n\n

    Begin tempering immediately once the workpiece cools to 52\u201365\u00b0C (125\u2013150\u00b0F) \u2014 do not allow it to reach room temperature first. Temper at 150\u2013260\u00b0C (300\u2013500\u00b0F). Minimum soak time: 2 hours per inch (4.7 min\/mm) of cross-section, followed by air cooling.<\/p>\n\n\n\n

    For demanding applications, double tempering is preferred. For most tooling, a single temper at 175\u2013205\u00b0C (345\u2013400\u00b0F) achieves a working hardness of 58\u201362 HRC.<\/p>\n\n\n\n

    Hardness vs. tempering temperature:<\/strong><\/p>\n\n\n\n

    Tempering Temperature \u00b0C (\u00b0F)<\/th>Hardness (HRC)<\/th><\/tr><\/thead>
    150 (300)<\/td>62.5<\/td><\/tr>
    205 (400)<\/td>59.5<\/td><\/tr>
    260 (500)<\/td>56.5<\/td><\/tr>
    315 (600)<\/td>54.0<\/td><\/tr>
    370 (700)<\/td>52.0<\/td><\/tr>
    425 (800)<\/td>49.5<\/td><\/tr>
    480 (900)<\/td>46.0<\/td><\/tr>
    540 (1000)<\/td>41.5<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

    Common Issues and Solutions<\/h2>\n\n\n\n

    Deformation and Dimensional Changes<\/h3>\n\n\n\n

    Deformation in O2 steel is usually caused by excessive quench rates or uneven heating. Three controls:<\/p>\n\n\n\n