鍛件廠家鋼件在淬火狀況下有以下三個要緊特性。

（1）構(gòu)造特性

根據(jù)鋼件尺寸、加熱溫度、光陰、轉(zhuǎn)變特性及行使的冷卻方式，鋼件淬火后的構(gòu)造要緊由馬氏體或馬氏體＋殘存奧氏體構(gòu)成，別的，還可能存在少許未溶碳化物。馬氏體和殘存奧氏體在室溫下都處于亞穩(wěn)定狀況，它們都有向鐵衆(zhòng)體加滲碳體的穩(wěn)定狀況轉(zhuǎn)化的趨向。

（2）硬度特性

由碳原子惹起的點陣畸變通過硬度顯露出來，它隨過飽和度（即含碳量)的增加而增加。淬火構(gòu)造硬度、強度高，塑性、韌性低。

（3）應(yīng)力特性

包含微觀應(yīng)力和宏現(xiàn)應(yīng)力，前者與碳原子惹起的點陣畸變相關(guān)，尤其是與髙碳馬氏體到達非常大值相關(guān)，分析淬火時馬氏體處于緊張受力狀況之中；后者是由于淬火時橫截面上形成的溫差而產(chǎn)生的，工件表面或心部所處的應(yīng)力狀況是差別的，有拉應(yīng)力或壓應(yīng)力，在工件里面保持平衡。如不及時消除淬火鋼件的內(nèi)應(yīng)力，會惹起零件的進一步變形甚至開裂。

綜上所述，淬火工件雖有髙硬度與髙強度，但跪性大，構(gòu)造不穩(wěn)定，且存在較大的淬火內(nèi)應(yīng)力，是以必須經(jīng)過回火處分才能應(yīng)用。普通來說，回火工藝是鋼件淬火后必不行少的后續(xù)工藝，它也是熱處分歷程的非常后一道工序，它賦予工件非常后所需求的機能。

Free forging steel parts have the following three critical characteristics under quenching conditions.

(1) Structural characteristics

According to the steel size, heating temperature, time, transformation characteristics and the cooling method, the structure of the steel after quenching is composed of martensite or martensite + residual austenite. In addition, there may be a little undissolved carbonization. Things. Martensite and residual austenite are metastable at room temperature, and they all have a tendency to convert to the stable state of the cement body plus cementite.

(2) hardness characteristics

The lattice distortion caused by the carbon atoms is revealed by the hardness, which increases as the degree of supersaturation (i.e., carbon content) increases. The quenched structure has high hardness and strength, and low plasticity and toughness.

(3) Stress characteristics

Including microscopic stress and macroscopic stress, the former is related to the lattice distortion caused by carbon atoms, especially related to the very large value of the martensite, and the martensite is in the state of stress during quenching; the latter is due to When the temperature difference formed on the cross section is obtained during quenching, the stress state of the surface or the core of the workpiece is different, and there is tensile stress or compressive stress to maintain balance in the workpiece. If the internal stress of the hardened steel is not removed in time, further deformation or even cracking of the part may occur.

In summary, although the quenched workpiece has 髙 hardness and 髙 strength, but the 跪 is large, the structure is unstable, and there is a large quenching internal stress, which must be applied after tempering. Generally speaking, the tempering process is a follow-up process that is indispensable after quenching steel. It is also a very late process of the heat treatment process, which gives the workpiece a very demanding function.