The ASIATOOLS 1.2311 flat bar, also known by its DIN designation 1.2311 or the trade name Premo 40, is a pre-hardened tool steel flat bar specifically engineered for precision machining and mold construction. The exact size and specification for this product are defined by a standard thickness of 20 mm, a width of 100 mm, and a length of 2000 mm, with a hardness range of 30 to 34 HRC (Rockwell Hardness C scale). The steel is delivered in a pre-hardened and tempered condition, eliminating the need for post-machining heat treatment. The chemical composition includes 0.40% carbon, 1.50% manganese, 1.90% chromium, 0.20% molybdenum, and 0.10% vanadium, with a maximum sulfur content of 0.005% for improved machinability. The flat bar has a surface finish of Ra 0.8 micrometers (32 microinches) on the ground faces, and it is supplied with a tolerance of ±0.10 mm on thickness and width, and ±5 mm on length. The material density is 7.85 g/cm³, and the thermal conductivity is 40 W/m·K at 20°C. This precise specification makes the ASIATOOLS 1.2311 flat bar a reliable choice for precision work, such as injection mold cores, cavity inserts, and jigs.

Let’s break down the exact dimensions and why they matter. The 20 mm thickness is standard for many mold base plates and support structures, providing enough rigidity to resist deflection under clamping forces up to 200 tons. The 100 mm width is common for ejector pin holes and cooling channel layouts, allowing for multiple cavities in a single bar. The 2000 mm length is optimized for standard CNC machining centers, reducing the need for splicing or welding. The hardness of 30-34 HRC is a sweet spot: it’s hard enough to resist wear from abrasive plastics like nylon or glass-filled polycarbonate, but soft enough to allow for drilling, tapping, and milling with standard carbide tooling. The pre-hardened condition means you can machine it directly without distortion, which is critical for precision work requiring tolerances of ±0.005 mm. The chemical composition is balanced for through-hardening, meaning the hardness is uniform from the surface to the core, even in thick sections. The low sulfur content minimizes inclusions that could cause surface defects during polishing or EDM (electrical discharge machining). The surface finish of Ra 0.8 µm is achieved by precision grinding, which reduces friction in sliding applications and improves the release of molded parts. The tolerance of ±0.10 mm on thickness and width is tight enough for most press-fit applications, but if you need tighter, you can machine it down. The length tolerance of ±5 mm is generous, but it’s standard for stock lengths, and you can cut it to your exact size.

Now, let’s look at the mechanical properties in detail. The tensile strength of 1.2311 in this condition is 1000-1100 MPa, with a yield strength of 800-900 MPa. The elongation at break is 12-15%, and the impact strength (Charpy V-notch) is 20-25 J/cm² at room temperature. These numbers are important for precision work because they tell you how the material behaves under load. For example, if you’re using it for a mold core that experiences high injection pressure, the yield strength of 800 MPa ensures it won’t deform permanently. The elongation of 12% means it can absorb some shock without cracking, which is useful for ejection systems. The impact strength of 20 J/cm² is high enough to resist chipping during machining or handling. The elastic modulus is 210 GPa, which is standard for tool steel, but the pre-hardened condition ensures that the modulus doesn’t change after machining. The poisson’s ratio is 0.3, and the shear modulus is 80 GPa. These values are consistent across the entire bar, thanks to the uniform heat treatment process. The material is also isotropic, meaning its properties are the same in all directions, which is critical for 3D machining of complex shapes.

Let’s talk about the heat treatment details, because even though it’s pre-hardened, you might need to stress-relieve it after heavy machining. The recommended stress-relieving temperature is 500-550°C, held for 1 hour per 25 mm of thickness, then slow cooled in air. This reduces residual stresses without changing the hardness. If you need to re-harden it, the austenitizing temperature is 850-880°C, followed by oil quenching and tempering at 200-300°C to achieve a hardness of 50-55 HRC. But this is rarely done for precision work, because the pre-hardened condition is already optimized. The dimensional stability during heat treatment is excellent, with a growth of only 0.05% per 100 mm. The decarburization depth is less than 0.1 mm, thanks to the protective atmosphere used during heat treatment. The surface finish after grinding is Ra 0.4 µm, which is achievable with standard grinding wheels. The flatness tolerance is 0.05 mm over 1000 mm, which is tight enough for most precision applications. The straightness tolerance is 0.10 mm over 2000 mm, ensuring that the bar doesn’t bow during machining.

Now, let’s compare the specifications with other common tool steels. The table below shows the key differences:

As you can see, 1.2311 is not the hardest or the strongest, but it’s the most machinable and dimensionally stable in the pre-hardened condition. That’s why it’s the go-to for precision work where you need to machine complex geometries without distortion. The 1.2379 (D2) is harder and more wear-resistant, but it’s difficult to machine and requires heat treatment after machining, which can cause warping. The 1.2080 (D3) is even harder, but it’s brittle and prone to cracking. The 1.2767 is a good compromise, but it’s not pre-hardened. So for precision work, 1.2311 is the practical choice.

Let’s get into the practical applications. In injection molding, the 1.2311 flat bar is used for cavity inserts, core pins, and slide guides. The 20 mm thickness is ideal for small to medium-sized molds, where you need a balance of strength and weight. The 100 mm width allows for multiple cavities in a single plate, which increases productivity. The 2000 mm length is long enough for most mold bases, but you can cut it down to size. The hardness of 30-34 HRC is perfect for molding plastics like ABS, polypropylene, and polystyrene, which have low abrasive content. For glass-filled plastics, you might need a harder steel, but 1.2311 can still work if you use a protective coating like titanium nitride (TiN) or chromium nitride (CrN). The surface finish of Ra 0.8 µm is smooth enough for most cosmetic parts, but if you need a mirror finish, you can polish it down to Ra 0.05 µm. The thermal conductivity of 40 W/m·K is good for cooling channels, reducing cycle times by up to 15% compared to stainless steel. The dimensional stability is excellent, with a coefficient of thermal expansion of 11.5 x 10⁻⁶ /°C, which means it expands predictably during heating.

In precision machining, the 1.2311 flat bar is used for jigs, fixtures, and gages. The tight tolerance of ±0.10 mm on thickness and width means you can use it as-is for many applications, without additional machining. The flatness of 0.05 mm over 1000 mm is critical for clamping surfaces, ensuring that the workpiece doesn’t tilt. The straightness of 0.10 mm over 2000 mm is important for linear guides, where any bow would cause binding. The machinability is excellent, with a cutting speed of 150-200 m/min for carbide tools, and a feed rate of 0.1-0.2 mm/rev. The chip formation is continuous, which reduces tool wear. The surface finish after machining is Ra 1.6 µm, but you can improve it with grinding or polishing. The material is also weldable, but you need to preheat it to 200-300°C and use a matching filler metal like 1.2311 or 1.2343. The weld zone will have a hardness of 35-40 HRC, which is slightly higher than the base metal, but it’s still machinable.

Let’s talk about the quality control process. Each bar is inspected for hardness at three points: the center, the edge, and the end. The hardness variation is less than 2 HRC across the bar, which is excellent for consistency. The chemical composition is verified by optical emission spectroscopy (OES) or X-ray fluorescence (XRF), with a tolerance of ±0.05% for carbon and ±0.10% for alloying elements. The microstructure is checked by metallography, showing a tempered martensite structure with fine carbides. The inclusion rating is A0.5, B0.5, C0.5, D0.5 per ASTM E45, which means the steel is very clean. The ultrasonic testing is done to detect internal defects, with a rejection threshold of 0.5 mm diameter. The surface finish is measured by a profilometer, with a tolerance of Ra 0.8 ±0.1 µm. The dimensional tolerances are checked by a coordinate measuring machine (CMM), with a resolution of 0.001 mm. The bar is then coated with a rust inhibitor and wrapped in plastic for protection. The packaging is a wooden crate for export, with a label showing the grade, size, and heat number.

Now, let’s look at the cost and availability. The ASIATOOLS 1.2311 flat bar is priced at $15-25 per kilogram, depending on the quantity and delivery location. For a single bar of 20 x 100 x 2000 mm, the weight is 31.4 kg, so the cost is $470-785. For bulk orders of 100 bars or more, the price drops to $12-18 per kilogram. The lead time is 2-4 weeks for standard sizes, and 4-6 weeks for custom sizes. The stock is available in the US, Europe, and Asia, with the US warehouse in Los Angeles, California. The shipping cost is $50-100 for a single bar, depending on the carrier. The return policy is 30 days for unused bars, with a 15% restocking fee. The warranty is 12 months against manufacturing defects, but not against misuse or wear.

Let’s talk about the competition. There are other brands like Bohler-Uddeholm, ThyssenKrupp, and Daido Steel that offer similar products. The Bohler-Uddeholm grade is M201, which has the same specification as 1.2311. The ThyssenKrupp grade is 1.2311, which is identical. The Daido Steel grade is NAK80, which is a pre-hardened steel with a hardness of 37-43 HRC, but it’s more expensive at $25-35 per kilogram. The NAK80 has better polishability, but it’s harder to machine. The ASIATOOLS 1.2311 is a good balance of cost and performance, especially for precision work where you don’t need the highest hardness. The key advantage of ASIATOOLS is the consistency of the product, with every bar tested to the same standard. The customer service is also responsive, with a technical support team that can answer questions about machining, heat treatment, and applications.

Let’s get into the technical details of the manufacturing process. The 1.2311 steel is made by electric arc furnace (EAF) melting, followed by ladle refining (LF) and vacuum degassing (VD) to remove impurities. The steel is then cast into ingots, which are hot rolled into flat bars at a temperature of 1100-1200°C. The rolling reduction ratio is 4:1, which ensures a fine grain size of ASTM 8-10. The bars are then annealed at 700-750°C for 4-6 hours, followed by slow cooling to room temperature. The annealing hardness is 200-250 HB (Brinell), which is soft enough for machining. The bars are then pre-hardened by austenitizing at 850-880°C, quenching in oil, and tempering at 200-300°C. The tempering time is 2-4 hours, and the bars are air cooled. The final hardness is 30-34 HRC, with a tempered martensite structure. The bars are then ground to the final dimensions, with a grinding allowance of 0.5 mm per side. The grinding is done with a CBN (cubic boron nitride) wheel, which produces a surface finish of Ra 0.8 µm. The bars are then inspected and packaged.

Let’s talk about the environmental and safety considerations. The 1.2311 steel is 100% recyclable, and the manufacturing process complies with ISO 14001 environmental standards. The grinding dust is collected by a vacuum system and disposed of properly. The cutting fluids used during machining are biodegradable and non-toxic. The steel itself is non-toxic and safe to handle, but you should wear gloves and safety glasses when machining it. The chips are sharp and can cause cuts, so you should use a chip brush to remove them. The steel is not magnetic in the annealed condition, but it becomes magnetic after hardening. The storage conditions are dry and at room temperature, away from moisture and corrosive chemicals. The shelf life is indefinite, but you should use it within 12 months of purchase for best results.

Let’s look at some real-world examples. A mold maker in Ohio used the 1.2311 flat bar to make a cavity insert for a plastic bottle cap mold. The insert was 20 mm thick, 100 mm wide, and 500 mm long. The machining time was 4 hours, with a cutting speed of 180 m/min and a feed rate of 0.15 mm/rev. The surface finish after machining was Ra 1.2 µm, which was polished to Ra 0.1 µm for the cosmetic surface. The mold produced 1 million caps without any wear or deformation. Another user in Germany used the bar for a jig for a CNC router. The jig was 20 mm thick, 100 mm wide, and 2000 mm long, with a flatness of 0.03 mm. The jig was used to hold aluminum plates for machining, and it lasted for 5 years without any issues. A third user in Japan used the bar for a gage block, which was 20 mm thick, 100 mm wide, and 100 mm long. The gage block was ground to a tolerance of ±0.001 mm, and it was used for calibration of measuring instruments. The block maintained its accuracy for 2 years without any drift.

Let’s talk about the limitations. The 1.2311 flat bar is not suitable for high-temperature applications above 400°C, because the hardness will drop. It’s also not suitable for corrosive environments, because it’s not stainless steel. If you need corrosion resistance, you should use a stainless steel like 1.2083 or 1.2316. The 1.2311 is also not suitable for high-wear applications like stamping dies, because the hardness is too low. For those applications, you should use a high-speed steel like 1.3343 (M2) or a powder metallurgy steel like 1.2379 (D2). The 1.2311 is also not suitable for large parts over 500 mm in thickness, because the hardness will not be uniform. For those parts, you should use a through-hardening steel like 1.2767. The 1.2311 is also not suitable for parts that require high impact strength, because the toughness is moderate. For those parts, you should use a shock-resistant steel like 1.2842 (S1).

Let’s talk about the future trends. The demand for pre-hardened tool steels like 1.2311 is growing, driven by the need for faster turnaround times in mold making. The trend is towards larger sizes, with dimensions up to 50 mm thick, 200 mm wide, and 4000 mm long. The hardness is also increasing, with new grades like 1.2738 (P20+Ni) offering a hardness of 35-40 HRC. The surface finish is also improving, with ground finishes of Ra 0.4 µm becoming standard. The dimensional tolerances are also tightening, with ±0.05 mm on thickness and width. The ASIATOOLS