Great changes have been made in the traditional pre heat treatment, such as spheroidizing annealing or isothermal spheroidizing annealing, which was widely used in cold working and hot working dies, but now some of them have been treated by quenching and tempering or ultra refining. Reasonable quenching and tempering process can obtain good original structure, improve the quenching process performance and enhance the strength and toughness after quenching

1）调质处理的主要作用

1) Main functions of quenching and tempering treatment

（1）获得分布均匀、颗粒细小、形状圆整的碳化物。

(1) The carbides with uniform distribution, fine particles and round shape are obtained.

（2）可有效地克服粗大珠光体、二次碳化物网或轻微带状偏析，以及大截面模块心部的铸态组织。

(2) It can effectively overcome the coarse pearlite, secondary carbide network or slight band segregation, as well as the as cast structure in the center of large section module.

（3）可充分加工后的残余应力，减少淬火变形。

(3) It can eliminate the residual stress and reduce the quenching deformation.

（4）可作为预硬化处理。

(4) It can be used as pre hardening treatment.

2）调质处理的典型用途

2) Typical uses of quenching and tempering treatment

（1）改进表面加工质量如碳工钢或低合金工具钢退火后硬度过低，加工后表面光洁度太差，可补充调质成硬度为183～229 HB的细球化体组织，能显著改善表面加工质量。对40Cr、45等中碳钢，调质到260～300HB时，精加工后能获得高的光洁度。

(1) For example, the hardness of carbon steel or low alloy tool steel after annealing is too low, and the surface finish is too poor after processing. The fine spheroidized structure with hardness of 183-229hb can be added and tempered, which can significantly improve the surface processing quality. For medium carbon steels such as 40Cr and 45, when quenched and tempered to 260-300hb, high finish can be obtained after finishing.

（2）防止淬火开裂

(2) Prevent quenching cracking

用于冷态辗轧、校直的成型轧辊，大多采用 9Cr2或Cr2钢制作，一般采用喷水淬火或用氢氧化钠水溶液浸淬，由于形状复杂，易于淬裂，例如在精加工前，调质为硬度197～229HB的细球化体既能保证良好的淬透性，又可以有效地降低淬裂倾内。

The forming rolls used for cold rolling and straightening are mostly made of 9Cr2 or CR2 steel. Generally, they are quenched by water spraying or by soaking with sodium hydroxide solution. Because of their complex shape, they are easy to crack. For example, before finishing, the fine spheroidized body with hardness of 197-229hb can not only ensure good hardenability, but also effectively reduce the quenching crack inclination.

（3）保证淬硬性

(3) Guarantee hardenability

φ30mmCr2钢轧辊，盐浴加热淬火后的硬度与毛坯的预处理工艺有关。退火毛坯的淬火硬度为65～66.5HRC，平均66HRC；调质（毛坯850℃淬油，660～680回火，229HB）的淬火硬度为66～67HRC，平均66.8HRC，且硬度高而均匀，未发生淬裂。

The hardness of 30mmcr2 steel roll after salt bath quenching is related to the pretreatment process of blank. The quenching hardness of annealed blank is 65-66.5hrc, with an average of 66hrc; the quenching hardness of quenched and tempered blank (850 ℃ oil quenching, 660-680 tempering, 229hb) is 66-67hrc, with an average of 66.8hrc, and the hardness is high and uniform, without quenching crack.

（4）用于预硬化模块的强化处理铝合金压铸模采用渗氮表面强化时，均应采用调质工艺进行预强化处理。塑料模具、冲压有色金属薄板或箔料的凹模，也可采用调质预强化。调质后再进行精加工。

(4) When nitriding surface strengthening is used for pre hardening module, quenching and tempering process should be used for pre hardening. Plastic mold, stamping non-ferrous metal sheet or foil die, can also use quenching and tempering pre strengthening. After quenching and tempering, finish machining is carried out.