Basic Information

H13 has good comprehensive performance at medium temperature (~600°), high hardenability (can harden in air), and low deformation rate during heat treatment, with performance and service life superior to3Cr2W8V.H13 steel has high toughness and resistance to thermal and cold fatigue, is not prone to thermal fatigue cracks, and has strong anti-adhesion, with minimal interaction with molten metal. It is widely used in the manufacturing of hot forging, hot extrusion, and die-casting molds, especially suitable for die-casting molds, producing castings with good appearance quality and longer mold service life. At the same time, this steel has high thermal strength, making it a strong and tough, cost-effective steel type, particularly welcomed by manufacturers of die-casting molds.

As a die-casting mold, the main factors affecting its lifespan are: thermal fatigue (i.e., cracking) caused by thermal cycling; during die-casting, molten metal is injected into the cavity mold, where erosion and corrosion occur at the mold parts in direct contact with high-temperature metal. Therefore, improving the thermal fatigue performance and corrosion resistance of the mold is an effective way to enhance the lifespan of H13 steel die-casting molds.

Due to nitriding, which can improve the thermal fatigue and corrosion resistance of the mold, preliminary heat treatment of H13 steel die-casting molds is conducted through quenching + tempering, followed by nitriding composite heat treatment experimental research. It was found that the new process significantly improves the surface hardness, wear resistance, thermal fatigue resistance, and corrosion resistance of H13 steel die-casting molds compared to traditional processes, with mold service life increased by 1 time.

Mechanical Properties

GeneralDelivery Condition : Annealed, 245～205HB,

Quenching+ Secondary Tempering ≥50HRC,

1030℃ oil quenching, 565℃ tempering, hardness about 49--52HRC, secondary tempering at 580℃, hardness about 47--50HRC,Tensile StrengthApproximately 1400 to 1500 MPa (workpiece φ900x300, featuring a simple-shaped cavity)

Used at temperatures of 450--500℃,Yield StrengthAbout 1100MPa,

H13 Delivery Condition

Brinell HardnessHBW10/3000 (≤229)

Main Characteristics of H13

H13 Steelis the most widely used and representativeof hot work tool steels, its main characteristics are:(1) High hardenability

and high toughness;(2) Excellent resistance to thermal cracking, can be water-cooled in working conditions;(3) Moderate wear resistance, and can also use carburizing or nitriding processes to improve its

surface hardness

, but this slightly reduces thermal cracking resistance;(4) Due to its low carbon content, secondary hardening during tempering is poor;(5) Has resistance to softening at higher temperatures, but hardness rapidly decreases when used at temperatures above 540℃ (1000℉) (i.e., the working temperature it can withstand is 540℃);

(6) Small deformation during heat treatment;(7) Moderate to high machinability;(8) Moderate decarburization resistance.

More notably, it can also be used to manufacture important components in theaerospace industry.H13 Applications

（6）热处理的变形小；

（7）中等和高的切削加工性；

（8）中等抗脱碳能力。

更为令人注意的是，它还可用于制作航空工业上的重要构件。

H13生活用途

Applications and9CRWMN mold steelBasically the same, but due to itsVanadium contentis higher, so the medium temperature (600 degrees) performance is better than4Cr5MoSiVsteel, it ishot work mold steela widely used type ofof hot work tool steels, its main characteristics are:steel grade.

H13 mold steelis used to manufactureimpact loadlargeforging dies,hot extrusion molds,precision forging molds; aluminum, copper and their alloysdie castingmolds.

Quenching: 790 degrees +-15 degrees preheating, 1000 degrees (salt bath) or 1010 degrees (furnace controlled atmosphere) +-6 degrees heating, holding for 5~15 minutes air cooling, 550 degrees +-6 degrees tempering; annealing, hot processing;

H13 detailed explanation

H13 Steelis C-Cr-Mo-Si-V type steel, which is extremely common in the world, and many scholars in various countries have conducted extensive research on it, exploringchemicalcompositionimprovements. The wide application of steel and its excellent characteristics are mainly determined by the chemical composition of the steel. Of course, the impurity elements in the steel must be reduced. Data shows that when Rm is 1550MPa, the materialcontainssulfurcontentis reduced from 0.005% to 0.003%, it will increase theimpact toughnessby about 13J. The NADCA 207-2003 standard stipulates that premium H13 steel has a sulfur content of less than 0.005%, while superior should be less than 0.003% S and 0.015% P. Below is an analysis of the composition of H13 steel. Carbon: AmericanAISI H13, UNS T20813,ASTM(latest version) stipulates that the carbon content of H13 and FED QQ-T-570 H13 steel is (0.32~0.45)%, which is the widest range of carbon content among all H13 steels. The carbon content of German X40CrMoV5-1 and 1.2344 is (0.37~0.43)%, with a narrower range of carbon content. In GermanDIN17350, the carbon content of X38CrMoV5-1 is (0.36~0.42)%. The carbon content of Japanese SKD 61 is (0.32~0.42)%. In our countryGB/T 1299 and YB/T 0944Cr5MoSiV1and SM 4Cr5MoSiV1 have carbon contents of (0.32~0.42)% and (0.32~0.45)%, which are the same asSKD61and AISI H13. It is particularly noteworthy that the North American Die Casting Association NADCA 207-90, 207-97, and 207-2003 standards all stipulate the carbon content of H13 steel as (0.37~0.42)%. The carbon content in steel determines

the matrix hardness of quenched steel. According to the curve of the relationship between carbon content in steel and the hardness of quenched steel, it can be known that thequenching hardnessof H13 steel is around 55HRC. Fortool steelin terms of, part of the carbon in the steel enters the matrix of the steel, causingsolid solution strengthening. Another part of the carbon will combine withthe alloy elementsto form carbide forming elementsto combine into alloycarbides. For, this alloy carbide, except for a small amount of residue, also requires it to precipitate during the tempering process on the quenchedmartensitematrix to produce a secondary hardening phenomenon. Thus, the performance of hot work mold steel is determined by the uniformly distributed residual alloy carbides and the structure of the tempered martensite. It can be seen that the carbon content in steel cannot be too low. H13 steel containing 0.5% Cr should have high toughness, so its carbon content should be maintained at a level that forms a small amount of alloy carbides. Woodyatt and Krauss pointed out that at 870℃ on the Fe-Cr-Chot work mold steelternary phase diagramthe position of H13 steel is inaustenite.均匀分布的残留合金碳化合物和回火马氏体的组织来决定热作模具钢的性能。由此可见，钢中的含C量不能太低。

含0.5%Cr的H13钢应具有高的韧度，故其含C量应保持在形成少量合金C化物的水平上。Woodyatt 和Krauss指出在870℃的Fe-Cr-C三元相图上,H13钢的位置在奥氏体The junction position of A and (A+M3C+M7C3) three-phase region is better. The corresponding C content is about 0.4%. The figure also indicates that increasing the C or Cr content increases the amount of M7C3, resulting in higher wear resistance of A2 and D2 steels.For comparison.Additionally, it is important to maintain a relatively low C content to ensure that the Ms point of the steel is at a relatively high temperature level (the Ms of H13 steel is generally introduced as around 340°C), allowing the steel to obtain a microstructure mainly composed of martensite with a small amount of residual A and uniformly distributed alloy carbides after quenching to room temperature, and obtaining a uniform tempered martensite structure after tempering.Martensite structure.Avoid excessive.Residual austenite.In.aerospace industry.The transformation that affects the working performance or deformation of the workpiece. These small amounts of residual austenite should be completely transformed during the two or three tempering processes after quenching. It is worth noting that the martensite structure obtained from H13 steel after quenching consists of lath M + a small amount of plate M + a small amount of residual A. Domestic scholars have also done some work on the very fine alloy carbides precipitated on lath M after tempering.

It is well known that increasing the carbon content in steel will improve the strength of the steel, and for hot work die steel, it will increase high-temperature strength, hot hardness, and.Wear resistance.However, it will lead to a decrease in toughness. Scholars have clearly demonstrated this point in the literature comparing the performance of various.H-type steels.It is generally believed that the carbon content limit that leads to a decrease in steel plasticity and toughness is 0.4%. Therefore, it is required that when designing steel.Alloying.Follow the principle of minimizing the carbon content of the steel while maintaining strength. Some data have suggested that when the strength of steel exceeds 1550MPa, a C content of 0.3%-0.4% is appropriate. The strength Rm of H13 steel is reported in the literature as 1503.1MPa (at 46HRC) and 1937.5MPa (at 51HRC).Tensile StrengthRefer to the recommended C content of TQ-1, Dievar, and other steels from FORD and GM companies, which are 0.39% and 0.38%, respectively, and the corresponding toughness indicators are listed in Table 1, which can be inferred from this.

For hot work die steels that require higher strength, the method used is to increase the Mo content or increase the carbon content based on the composition of H13 steel, which will be discussed later. Of course, a slight decrease in toughness and plasticity is to be expected.ADC32.2 Chromium: Chromium is.

The most commonly contained and inexpensive alloying element in alloy tool steels. In American H-type hot work.

Die steels.The Cr content ranges from 2% to 12%. In China, among the 37 steel grades of alloy tool steel (GB/T1299), all contain Cr except for 8CrSi.Chromium has a beneficial effect on the wear resistance, high-temperature strength, hot hardness, toughness, and.It also significantly improves the corrosion resistance of steel when dissolved in the matrix.In H13 steel, the presence of Cr and Si can densify the.Oxide film.To improve the steel's.9Mn2VOxidation resistance.(2) Excellent resistance to thermal cracking, can be water-cooled in working conditions;Furthermore, analyzing the effect of Cr on the tempering performance of 0.3C-1Mn steel, adding <6% Cr is beneficial for improving the.Tempering resistance.However, it does not form.When steel with Cr > 6% is quenched and tempered at 550°C, a secondary hardening effect occurs. Generally, a chromium addition of 5% is selected for hot work tool steels.In tool steels, part of the chromium dissolves in the steel to play.Solid solution strengthening.Another part combines with carbon, existing in the forms of (FeCr)3C, (FeCr)7C3, and M23C6, thereby affecting the performance of the steel. Additionally, the.Interaction.Of alloying elements must also be considered. For example, when chromium, molybdenum, and vanadium are present in the steel, when Cr > 3%, Cr can prevent the formation of V4C3 and delay the coherent precipitation of Mo2C. V4C3 and Mo2C are strengthening phases that improve the high-temperature strength and.(7) Moderate to high machinability;Tempering resistance.

This interaction enhances the heat-resistant deformation performance of the steel.Chromium dissolves into the steel austenite, increasing the hardenability of the steel. Cr, Mn, Mo, Si, and Ni are all alloying elements that, like Cr, increase the hardenability of steel. People are accustomed to characterizing hardenability with a hardenability factor, and generally, existing domestic data only apply Grossmann et al.'s data. Later, further work by Moser and Legat proposed that the basic hardenability diameter Dic is determined by the carbon content and.Austenite grain size.The hardenability factor determined by the alloying element content (as shown in Figure 3) is used to calculate.The ideal.Critical diameter.Di can also be approximately calculated from the following formula:

Di=Dic×2.21Mn×1.40Si×2.13Cr×3.275Mo×1.47Ni (1)奥氏体晶粒度决定基本淬透性直径Dic和合金元素含量确定的淬透性因子(示于图3中)来计算合金钢的理想临界直径Di,也可从下式作近似计算:

Di=Dic×2.21Mn×1.40Si×2.13Cr×3.275Mo×1.47Ni (1)

In the formula, each alloy element is expressed as a masspercentageFrom this formula, people have a fairly clear understanding of the influence of Cr, Mn, Mo, Si, and Ni elements on the hardenability of steel.Semi-quantitativeunderstanding.

The effect of Cr on steelEutectoid pointis roughly similar to that of Mn, where the carbon content at the eutectoid point drops to about 0.5% with a chromium content of about 5%. Additionally, the addition of Si, W, Mo, V,Tisignificantly reduces the carbon content at the eutectoid point. Therefore, it can be understood that: hot work tool steel andhigh-speed steelare both classified ashypoeutectoid steel.The reduction of carbon content at the eutectoid point will increasethe austenitizingand the content of alloy carbides in the final structure.

The behavior of alloy carbides in steel is related to their own stability. In fact, the structure and stability of alloy carbides are related to the delectron shelland the s electron shell'selectron deficiencydegree. As the degree of electron deficiency decreases, the metalatomic radiusdecreases, and the atomicradius ratio of carbon tometal elementsincreases, causing alloy carbides to change from interstitial phases tointerstitial compounds.The stability of carbides weakens, and their correspondingmelting temperatureand solubility temperature in A decrease, and theirfree energy of formationabsolute valuedecreases, leading to a correspondingdecrease in hardness.VCcarbide, which has a face-centered cubic lattice, is highly stable, starting to dissolve at about 900~950℃, and begins to dissolve in large quantities above 1100℃ (the dissolution termination temperature is 1413℃); it precipitates during tempering at 500~700℃, does not easily aggregate and grow, and can serve as a strengthening phase in steel. The medium carbides formed by elements W, Mo form M2C and MC carbides with close-packed and simple hexagonal lattices, which have relatively poorer stability, but still possess high hardness, melting points, and dissolution temperatures, and can still serve as strengthening phases for steel used in the range of 500~650℃. M23C6 (such as Cr23C6, etc.) has a complex cubic lattice, poorer stability, weaker bonding strength, and lower melting and dissolution temperatures (dissolves in A at 1090℃), and only has higher stability after comprehensive alloying in a fewheat-resistant steels.M7C3 (such as Cr7C3, Fe4Cr3C3, or Fe2Cr5C3) with a complex hexagonal structure has even poorer stability, and like Fe3C-type carbides, it easily dissolves and precipitates, with a large aggregation and growth rate, and generally cannot serve as a high-temperature strengthening phase.We can still easily understand the alloy carbide phase in H13 steel from the Fe-Cr-C ternaryphase diagram.

According to the isothermal sections of the Fe-Cr-C system at 700℃ and 870℃, for steel containing 0.4%C, as the Cr content increases, (FeCr)3C (M3C) and (CrFe)7C3 (M7C3) type alloy carbides will appear. Note that in the 870℃ diagram, M23C6 will only appear when the Cr content is greater than 11%. Additionally, according to the Fe-Cr-Cternary systemat 5% Cr, for steel containing 0.40%C, in theannealed stateIn the phase diagram, for steel containing 0.4%C, with the increase of Cr content, (FeCr)3C (M3C) and (CrFe)7C3 (M7C3) type alloy carbides will appear. Note that on the diagram at 870℃, M23C6 will only appear when the Cr content is greater than 11%. Additionally, according to Fe-Cr-C.At about 970℃, (CrFe)7C3 disappears, entering the single-phase A region. When the matrix carbon content is <0.33%, the (M7C3+M23C6 and A) three-phase region only exists at around 793℃, entering the (A+M7C3) region at 796℃ (at 0.30%C), and continues to maintain until the liquid phase. The residual M7C3 in steel has the effect of preventing Agrain growth.Nilson proposed that for an alloy with a composition of 1.5%C-13%Cr, the unstable (CrFe)23C6 does not form. Of course, analyzing solely based on the Fe-Cr-C ternary system may have some deviations, and the influence of added alloy elements should be considered.Introduction to heat treatment and surface treatment of H13 steelHeat treatment process.The pre-heat treatment of H13 steel is carried out in a high-temperature salt bath furnace. To reduce thermal stress in H13 steel die casting and promote austenite homogenization, segmental preheating should be done before reaching the austenitizing temperature. Therefore, before entering the salt bath furnace, two segments of preheating at 550℃ for 40 minutes and 850℃ for 40 minutes should be used, with salt heating at 1030℃ being optimal.晶粒长大的作用。Nilson提出，对1.5%C-13%Cr的成分合金，欠稳定（CrFe）23C6不形成[20]。当然,单以Fe-Cr-C三元系分析会有一些偏差,要考虑加入合金元素的影响。

H13钢热处理、表面处理使用介绍

热处理工艺。

H13钢预先热处理加热是在高温盐浴炉中进行的。为减少H13钢压铸模的热应力和促进奥氏体均匀化，在达到奥氏体化温度前应进行分段预热。因此在进入盐浴炉前，应采用550℃+40min和850℃+40min的两段预热，盐加热以1030℃为最佳。

 Nitrogen-carbon co-diffusion heat treatment of H13 steel die casting molds

The reason for choosing nitrogen-carbon co-diffusion for H13 steel die casting molds is that this process is carried out at a low temperature range (500-600℃), where the solid depth of carbon atoms in iron is lower than that of nitrogen atoms. Due to the mutual promotion effect of nitrogen and carbon atoms, the co-diffusion speed is greatly increased. Considering that nitrogen-carbon co-diffusion does not affect the matrix hardness of H13 steel die casting molds, the co-diffusion temperature should be lower than the tempering temperature.

Nitrogen-carbon co-diffusion process.

The nitrogen-carbon co-diffusion heat treatment of H13 steel die casting molds is carried out in normal gas nitrogen-carbon co-diffusion heat treatment production. Before nitrogen-carbon co-diffusion, the H13 steel die casting molds that have undergone preparatory heat treatment must be finely processed (grinding, electrical discharge machining, etc.). Before loading into the furnace, they must be degreased with gasoline or alcohol, and the working surface must be free of rust or dirt after cleaning.

The nitrogen-carbon co-diffusion medium for H13 steel die casting molds is ammonia + ethanol, and the process is 580℃*4.5h.

 Microstructure and properties after nitrogen-carbon co-diffusion

(1) Diffusion layer structure.

The microstructure of H13 steel samples after nitrogen-carbon co-diffusion consists of Fe2N, Fe3N, Fe4N, and alloy nitrides such as C, Mo, and V.

(2) Thickness of the nitrogen diffusion layer and surface hardness.

The thickness of H13 samples after nitrogen-carbon co-diffusion is approximately 0.20mm, with a surface hardness of 900HV. The wear resistance is high, and compared to samples that have been tempered and high-frequency quenched, the weight loss due to wear can be reduced by 1-2 orders of magnitude or significantly decreased.

(3) Fatigue resistance.

After nitrogen-carbon co-diffusion, due to the surface being in a state of compressive stress and the dispersion of precipitates hindering dislocation movement, the fatigue limit after nitrogen-carbon co-diffusion is improved by 25%-35% compared to the fatigue limits of carburizing and high-frequency quenching.

The results of quenching, tempering, and then nitrogen-carbon co-diffusion of H13 steel die casting molds lead to the following conclusions:

(1) Quenching and tempering H13 steel die casting molds before nitrogen-carbon co-diffusion can achieve higher surface hardness, wear resistance, fatigue resistance, and corrosion resistance. At the same time, gas nitrogen-carbon co-diffusion is equivalent to a first tempering after mold quenching and processing, resulting in minimal mold deformation.

(2) The gas nitrogen-carbon co-diffusion layer has characteristics such as a short production cycle, low temperature, simple equipment, and convenient operation.

(3) Production practice shows that the service life of H13 steel die casting molds subjected to quenching, tempering, and then nitrogen-carbon co-diffusion heat treatment is more than twice that of conventional heat treatment.

(4) The optimal heat treatment process for H13 steel die casting molds is: quenching at 1030℃, tempering at 600℃, followed by mold adjustment, and then performing gas nitrogen-carbon co-diffusion at 580℃ for 4.5 hours, followed by oil cooling after nitrogen diffusion.