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Forging method of relatively-large-size fine-grained austenitic gas valve steel SNCrW

A technology of austenitic and gas valve steel, which is applied in the forging field of large-scale fine-grained austenitic stainless steel SNCrW bars for gas valves. Problems such as fast precipitation speed, to achieve the effect of localization

Active Publication Date: 2020-03-31
FUSHUN SPECIAL STEEL SHARES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, due to the high content of C, Cr, and W in SNCrW steel, the segregation of primary carbides is serious; the thermal conductivity is large, the temperature drop at the corner of the billet is fast, and the secondary carbides are precipitated quickly and in large quantities; the structure of the center is thick; in forging, Defects such as low-magnification coarse grains, elongated grains of carbide aggregation, and failure of ultrasonic flaw detection are prone to appear on the as-rolled bar

Method used

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  • Forging method of relatively-large-size fine-grained austenitic gas valve steel SNCrW
  • Forging method of relatively-large-size fine-grained austenitic gas valve steel SNCrW
  • Forging method of relatively-large-size fine-grained austenitic gas valve steel SNCrW

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0045] Produce SNCrW round steel with a size of Φ88mm.

[0046] 1. The smelting branch produces SNCrWΦ480mm electroslag ingots with qualified chemical composition;

[0047] 2. The electroslag ingot after high-temperature homogenization treatment is kept at 1200°C for 2 hours and then out of the furnace for forging;

[0048] 3. The fast forging machine performs upsetting operation, the upsetting reduction is 300mm, adopts the forging method at both ends, the 80mm reduction is drawn to a 450mm octagonal cross section, the end of the bottom pad is clamped, and the furnace is refired at 1200°C for 3 hours;

[0049] 4. The octagonal process of the quick forging machine is drawn to a 360mm octagonal section, of which the first pass is pressed to a ruler of 360mm, the second pass is 120mm to reduce the length, and the third and fourth passes are pressed to a ruler of 360mm. The pass is shaped according to the billet size of 360mm, and the final forging temperature of the corner is 9...

Embodiment 2

[0055] Produce SNCrW round steel with a size of Φ100mm.

[0056] 1. The smelting branch produces SNCrWΦ480mm electroslag ingots with qualified chemical composition;

[0057] 2. The electroslag ingot after high-temperature homogenization treatment is kept at 1210°C for 3 hours and then out of the furnace for forging;

[0058] 3. The fast forging machine performs upsetting operation, the upsetting reduction is 350mm, adopts the forging method at both ends, the 80mm reduction is drawn to a 450mm octagonal section, the end of the bottom pad is clamped, and the furnace is refired at 1200°C for 2.5 hours;

[0059] 4. The octagonal process of the quick forging machine is drawn to a 370mm octagonal cross-section, of which the first pass is pressed to a ruler of 370mm, the second pass is 120mm to reduce the length, and the third and fourth passes are pressed to a ruler of 370mm. The pass is shaped according to the billet size of 370mm, and the final forging temperature of the corner i...

Embodiment 3

[0065] Produce SNCrW round steel with a size of Φ115mm.

[0066] 1. The smelting branch produces SNCrWΦ480mm electroslag ingots with qualified chemical composition;

[0067] 2. The electroslag ingot after high-temperature homogenization treatment is kept at 1220°C for 4 hours and then out of the furnace for forging;

[0068] 3. The fast forging machine performs upsetting operation, the upsetting reduction is 350mm, adopts the forging method at both ends, the 80mm reduction is drawn to a 450mm octagonal section, the end of the bottom pad is clamped, and the furnace is refired at 1200°C for 2 hours;

[0069] 4. The octagonal process of the quick forging machine is drawn to a 380mm octagonal cross-section, of which the first pass is pressed to a ruler of 380mm, the second pass is 120mm to reduce the length, and the third and fourth passes are pressed to a ruler of 380mm. The pass is shaped according to the billet size of 380mm, the final forging temperature of the corner is 930°...

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Abstract

The invention discloses a forging method of relatively-large-size fine-grained austenitic gas valve steel SNCrW. The forging method aims to solve the problems of serious primary carbide segregation ofas-cast structures of steel ingots, the large amount of secondary carbide precipitation of billet corners and thick and large core structures. According to the technical scheme, an EAF / non-vacuum induction furnace + LF + VOD / VHD + ESR smelting process is adopted to produce electroslag ingots with qualified chemical compositions, a radial rapid forging combining forging method is adopted, and through high-temperature homogenization treatment before forging and control over the heating temperature of billets, billet reburning time, upsetting amount, drawing reduction amount, deformation amountand a deformation mode per firing and length of radial forging billets, the problems of the as-cast structures of the ingots are solved. The forging method has the beneficial effects that macrostructures of relatively-large-size fine-grained austenitic stainless steel SNCrW bar products are qualified, the grain size is above 6 grade, and the flaw detection reaches the grade A required by GB / T 4162, the needs of domestic gas valve manufacturers are met, and the domestic production of SNCrW bars is realized.

Description

technical field [0001] The invention belongs to the field of thermal processing of metal materials, and in particular relates to a forging method for fine-grained austenitic stainless steel SNCrW rods with relatively large specifications (Φ85mm-Φ120mm) for gas valves. Background technique [0002] SNCrW belongs to austenitic heat-resistant stainless steel. The room temperature structure of forging and rolling is austenite + carbide. After solution + aging treatment, it has high strength, plasticity and toughness. At the same time, it has excellent high temperature fatigue strength and durability. Gas corrosion performance, suitable for manufacturing low-speed diesel engine valve products with high heat strength and corrosion resistance requirements. [0003] The good comprehensive performance of SNCrW steel requires a uniform structure. The main structure of the steel is that it contains a large number of carbides. These carbides include primary carbides in the as-cast struc...

Claims

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Application Information

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IPC IPC(8): B21J5/00B21K29/00C22C33/06C21D8/06C21D9/00C21D6/00
CPCB21J5/002B21J5/008B21K29/00C21D6/002C21D8/065C21D9/0075C22C33/06
Inventor 谭庆丰王继红陈德利卢伦崔鴻秋立鹏张丽娜刘玉芬赵艳韩志远叶强陈庆新
Owner FUSHUN SPECIAL STEEL SHARES
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