无缝异型钢管为优质碳素结构用钢 ,硬度不高易切削加工,模具中常用来做模板,梢子,导柱等,但须热处理 。 推荐热处理温度：正火850，淬火840，回火600。无缝异型钢管淬火后没有回火之前，硬度大于HRC55(最高可达HRC62)为合格。实际应用的最高硬度为HRC55(高频淬火HRC58)。 45号钢不要采用渗碳淬火的热处理工艺。 Cold-drawn seamless steel pipes are high quality carbon structural steels with low hardness and easy to cut. Dies are often used as templates, tips, guide pillars, etc., but heat treatment is required. Recommended heat treatment temperature: normalizing 850, quenching 840, tempering 600. The hardness of cold-drawn seamless steel tube is higher than HRC55 (up to HRC62) before quenching and tempering. The highest hardness in practical application is HRC55 (high frequency quenching HRC58). No. 45 steel should be treated by carburizing and quenching. 调质处理后零件具有良好的综合机械性能，广泛应用于各种重要的结构零件，特别是那些在交变负荷下工作的连杆、螺栓、齿轮及轴类等。但表面硬度较低，不耐磨。可用调质+表面淬火提高零件表面硬度。
After quenching and tempering, the parts have good comprehensive mechanical properties and are widely used in various important structural parts, especially those connecting rods, bolts, gears and shafts working under alternating loads. But the surface hardness is low and wear-resistant. Tempering and surface quenching can be used to improve the surface hardness of parts.
无缝异型钢管渗碳处理一般用于表面耐磨、芯部耐冲击的重载零件，其耐磨性比调质+表面淬火高。其表面含碳量0.8--1.2%，芯部一般在0.1--0.25%(特殊情况下采用0.35%)。经热处理后，表面可以获得很高的硬度(HRC58--62)，芯部硬度低，耐冲击。
Carburizing treatment of cold-drawn seamless steel tubes is generally used for heavy-duty parts with wear-resistant surface and impact-resistant core, and its wear resistance is higher than that of quenching and tempering plus surface quenching. Its surface carbon content is 0.8-1.2%, and its core is generally 0.1-0.25% (in special cases, 0.35%). After heat treatment, the surface can obtain high hardness (HRC58-62), low core hardness and impact resistance.
如果用45号钢渗碳，淬火后芯部会出现硬脆的马氏体，失去渗碳处理的优点。现在采用渗碳工艺的材料，含碳量都不高，到0.30%芯部强度已经可以达到很高，应用上不多见。0.35%从来没见过实例，只在教科书里有介绍。可以采用调质+高频表面淬火的工艺，耐磨性较渗碳略差。
If 45 steel is carburized, hard and brittle martensite will appear in the core after quenching, thus losing the advantage of carburizing treatment. At present, the material with carburizing process has not high carbon content, and the strength of 0.30% core has reached a high level, which is rarely used. 0.35% had never seen an example, only introduced in textbooks. The process of quenching and tempering plus high frequency surface quenching can be adopted, and the wear resistance is slightly worse than that of carburizing.
GB/T8162-2008标准规定的45号钢无缝异型钢管推荐热处理制度为850℃正火、840℃淬火、600℃回火，达到的性能为屈服强度≥355MPa。GB/T699-1999标准规定45钢抗拉强度为600MPa，屈服强度为355MPa，伸长率为16%，断面收缩率为40%，冲击功为39J。
According to GB/T8162-2008 standard, the recommended heat treatment system for cold-drawn seamless steel pipe 45 is normalizing at 850 (?), quenching at 840 (?) and tempering at 600 (?) C. The yield strength of the steel 45 is more than 355 MPa. GB/T699-1999 standard stipulates that the tensile strength of 45 steel is 600 MPa, the yield strength is 355 MPa, the elongation is 16%, the section shrinkage is 40%, and the impact energy is 39 J.
