According to customer drawlngs, we order the forged blanks from qualified suppliers. The major forged steels used for roils are of 2%|3%/5% chromo content. The forged blank should be ESR grade with forging ratio of more than 3. The ESR forged steel blank is free of white spots,inner cracks, contraction cavities, skuIl patches and of visual non-metal impurities.
2.QUENCHING AND TEMPERlNG
Quenching and tempering is the very Important pre—heattreament before hardening of r-oiis. The major purpose is to improve the mechianical characters of rolls which can help the rolls to have more strength and longer life.It can make the rolls of more wear-resistance and anti-accidents.
3.HARDENING (FINAL HEAT-TREATMENT)
Hardening to the roll barrel includes methods of FULL—BODY HEATING, SINGLE FREQUENCY HEATING as well as DOUBLE FREQUENCY HEATING.
4.DEEP COOLING TREATMENT
Deep cooling treatment is in between harderiing process and low temperature tempering process. By using liquid nitrogen or liquid carbon dioxide, it can cool the rolls down to 0 DEG C, normally at -70 to -85 DEG C for some times. 5.LOW TEMPERATURE TEMPERING The major purpose is to remove the residual stress and make the barrel hardness to achieve target value.
Customers are more strict to the precision of rolls to meet the requirements of higher rolling speed,better fineness and smoothness Of strlps,therefore,by Using all CNC mechanical processing machines is the only way to guarantee the same.
All rolls must be tested strictly by our QC department for following parameters:
(l) HARDNESS AND DEEPTH OF HARDNESS TEST
(2) METALLURGICAL STRUCTUlRE TEST
(3) GRAINI SIZE TEST
(4) RESIDUAL AUSTENITE TEST
(5) MEASUREMENTS AND GEOIVtETRIC TOLERANCE TEST